COVID-19 signs, symptoms and severity of disease: A clinician guide

Last updated: June 17, 2021

The information below is based on currently available scientific evidence and informed by expert clinician opinion, and is subject to change as new information becomes available. This document is meant to provide interim information to clinicians on what is presently known about the clinical features of COVID-19, including signs and symptoms, incubation period, disease severity and risk factors for severe disease, SARS-CoV-2 variants of concern and reinfection.

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Signs and symptoms

COVID-19 includes clinical features that present in varying type, frequency, severity and within different age groups. Published reports often over-represent individuals who have more severe symptoms and these may differ across care settings and between different age groups. Symptoms that are absent at the onset of illness may develop over time with disease progression. To date, there is no comprehensive list of symptoms that has been validated to have high specificity or sensitivity for COVID-19. It is possible, that as new variants emerge there may be changes in the patterns of symptoms that individuals display. Clinical diagnosis should therefore always be confirmed through SARS-CoV-2 laboratory testing. Patients should always be encouraged to seek medical consultation if experiencing new or worsening symptoms. Table 1 below outlines the common, less frequent and rare symptoms in COVID-19 individuals.

Table 1: Common, less frequent and rare symptoms for adults with COVID-19*
Common symptoms
>50%
Less frequent
(≤ 50%)
Rare symptoms
(<10%)
  • Fever
  • Chills
  • New or worsening cough
  • Fatigue and myalgia
  • Headache
  • Gastrointestinal symptoms (nausea, vomiting, diarrhea)
  • Shortness of breath or difficulty breathing
  • Sore throat
  • Painful and/or difficulty swallowing
  • Conjunctivitis
  • New or unusual exacerbation of chronic conditions
  • Delirium
  • Decreased or loss of appetite
  • New loss of smell and/or taste
  • Skin manifestations
  • Confusion
  • Runny/stuffy nose
  • Eye manifestations
*Note: It is important to evaluate whether the patient's symptoms are new, worsening, or different from their baseline.

Cough, fever and shortness of breath are the three most common features amongst hospitalized adult patients, while cough, fever and myalgia were the most common symptoms amongst non-hospitalized individuals.

Clinicians should be aware of signs and symptoms that warrant more urgent or emergency medical attention. Patients with mild disease should be informed to seek medical attention should they experience any of the following:

Fever

The frequency of fever varies amongst studies but remains one of the primary symptoms of COVID-19. A patient may not present with a fever, but may progress to one after a few days of experiencing other symptoms. Older adults and those with underlying comorbidities may experience fever and respiratory symptoms later during the course of illness, when compared to younger persons or those without comorbidities. A review of data from almost 25,000 adults found that fever was the most common symptom at a frequency of 78% of the cases. A study in China found that only 44% of people who stayed in the hospital for COVID-19 had fever upon admission. However, 89% experienced fever at some point during the hospitalization. In some cases, COVID-19 may occur without fever.

Cough and shortness of breath

Other more prevalent symptoms that have been reported include cough and shortness of breath. Cough is one of the most prevalent symptoms along with fever. Both dry (58%) and productive (25%) coughs have been described in the literature. Shortness of breath was more frequently reported in hospitalized patients and associated with more severe disease. A recent systematic review and meta-analysis found shortness of breath present amongst 44% of people with severe disease and 6% of people with non-severe disease.

Other symptoms

Many other symptoms have been associated with COVID-19. Of particular note, fatigue, myalgia, and loss of taste and/or smell are experienced in about 1/3 of all cases. Some uncommon symptoms found in COVID-19, but reported during acute illness include congestion or runny nose, skin rashes and eye issues (including conjunctivitis, eye pain and light sensitivity). These other symptoms do not typically occur on their own and are found in conjunction with the more prevalent symptoms. Some of the more uncommon symptoms may also become more prevalent as new variants emerge. Two rare but important syndromes associated with SARS-CoV-2 have been described in the literature and are called Multisystem Inflammatory Syndrome - Children (MIS-C) and Multisystem Inflammatory Syndrome - Adults (MIS-A). These are described below.

Multisystem Inflammatory Syndrome - Children (MIS-C)

In early 2020, this syndrome in children was newly recognized as related to SARS-CoV-2 infection and characterized by hyperinflammation and multi-organ involvement, and presenting with clinical features similar to Kawasaki disease and toxic shock syndrome. A recent systematic review and meta-analysis looking at 27 studies on 917 MIS-C cases found that the common manifestations amongst cases were gastrointestinal symptoms (87.3%) and cardiovascular involvement such as myocardial dysfunction (55.3%), coronary artery aneurysms (21.7%) and shock (65.8%), with marked elevated inflammatory and cardiac markers.

MIS-C signs and symptoms include:

Common laboratory findings in case reports have included:

In children presenting with a persistent fever (≥3 days) who are moderately to severely ill with clinical signs of organ dysfunction (e.g. gastrointestinal, respiratory, cardiac, skin, or neurologic), the diagnosis of MIS-C should be considered.

Multisystem Inflammatory Syndrome - Adults (MIS-A)

Since June 2020, several case reports and series have been published reporting a similar multisystem inflammatory syndrome in adults (MIS-A) that was previously identified in children. Three studies identified 27 patients who had cardiovascular, gastrointestinal, dermatologic, and neurologic symptoms without severe respiratory illness and who also have positive test results for SARS-CoV-2 by PCR or antibody assays indicating recent infection. Clinicians should consider MIS-A in adults with similar signs and symptoms as seen with MIS-C. It is important to note that 30% of adults and 45% of children with MIS-C/A reported a negative PCR and a positive SARS-CoV-2 antibody test results, suggesting MIS-A and MIS-C might represent a post-infectious process. If suspicious of MIS-C/A and a patient has a negative PCR test, consider both antibody and viral testing to assist with diagnosis.

Symptoms in children

A recent systematic review of the signs and symptoms of laboratory-confirmed COVID-19 disease in children and youth under 19 years of age found cases of asymptomatic positive laboratory tests ranged from 15% to 42%. Fever and cough were the most common symptoms; with the proportions with fever ranging from 46% to 64% and for cough from 32% to 56%. All other signs and symptoms were present at less than 10% to 20%. Vomiting, diarrhea and abdominal ranged from 7% to 18%.

A French multi-centre hospital, as part of a screening program, found that as many as half of paediatric cases were asymptomatic when screened on entry to the hospital. One should also consider when assessing children, that the signs and symptoms of COVID-19 are similar to those of other infections and non-infectious processes, including influenza, other viral upper respiratory infections, streptococcal pharyngitis, asthma and allergies. The lack of specificity of signs or symptoms and the significant proportion of asymptomatic infections make symptom-based screening for identification of SARS-CoV-2 in children difficult.

Symptoms in older adults

Symptoms amongst older adults may be atypical or subtle. Confusion, delirium, and/or loss of movement, mobility and speech may occur in older people. Fever, cough and shortness of breath may be absent or less common.
Symptoms in older adults that differ from typical symptoms include:

Asymptomatic, pre-symptomatic and pauci-symptomatic infection

A person who is asymptomatic is someone with a positive SARS-CoV-2 test who never develops any symptoms, whereas a person who is pre-symptomatic is someone who is infected with SARS-CoV-2 and may have detectable virus, but is not yet showing symptoms (these individuals develop symptoms later on in the course of infection). Individuals who are pauci-symptomatic will have a positive SARS-CoV-2 test in the presence of very limited symptomatology. A systematic review and meta-analysis looking at prevalence of SAR-CoV-2 in persons who are asymptomatic from 28 studies, found that 25% of COVID-19 cases were asymptomatic (95%CI: 16-38). Asymptomatic, pre-symptomatic and pauci-symptomatic SARS-CoV-2 infection and how much each of these contributes to transmission is still unknown.

Incubation period

The incubation period for COVID-19 has been estimated to range from 2 to 14 days, with a median of 5-6 days from exposure to symptom onset. Of all individuals who develop symptoms, 97.5% of the symptoms occur within 11.5 days of exposure. Note that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset. However, detection of viral RNA does not necessarily mean that the patient can transmit the virus. The time period in which an individual with COVID-19 can transmit the virus is said to be at a maximum of 10 days after symptom onset for immunocompetent people who have COVID-19. Evidence has shown that an individual may be infectious for up to 3 days prior to any presentation of symptoms. The levels of viral RNA from nasopharyngeal, saliva/sputum samples, upper respiratory specimens, and stool samples appear to be highest soon after symptom onset. A recent systematic review and meta-analysis found that SARS-CoV-2 cases with serial upper respiratory tract samples showed peak viral loads within the first week of symptom onset. The highest viral loads were reported soon after or at the time of symptom onset or at day 3-5 of illness, followed by a consistent decline.

Disease severity and risk factors for severe disease

There is a spectrum of COVID-19 disease severity, ranging from asymptomatic to mild, to moderate, severe and critical disease. Severe disease more often occurs in those with increasing age and those with underlying medical conditions, with the risk increasing with the number of underlying conditions.

Two large cohort studies in the USA and the UK found the most common comorbidities were hypertension (46.7%), hyperlipidemia (28.9%), diabetes (27.9%), and chronic pulmonary disease (16.1%). High risk for mortality was associated with increasing number of comorbid conditions. A comprehensive CDC scientific evidence review process and a Canadian rapid review have recently been published to update the list of underlying medical conditions associated with more severe COVID-19 disease. The conditions identified in these reviews are listed below:

Underlying medical conditions associated with more severe COVID-19 disease:

*Overweight = body mass index (BMI) > 25 kg/m2 but < 30 kg/m2), obesity (BMI ≥30 kg/m2 but < 40 kg/m2), or severe obesity (BMI of ≥40 kg/m2)

Patients with certain medical and/or social vulnerabilities, including people experiencing intellectual and developmental disabilities, persons who use substances regularly, people experience cognitive disabilities, mental health conditions or experiencing homelessness or are unhoused, may make it more difficult for the patient to recognize, clearly communicate, or act on symptom progression. These patients need closer attention and monitoring.

SARS-CoV-2 variants of concern (VOC)

Viruses naturally mutate or change over time. Mutations do not always increase transmissibility or virulence, or lead to suboptimal immune or therapeutic responses compared to non-variant viruses. Multiple SARS-CoV-2 variants have emerged in recent months and have shown increased transmissibility when compared with the original strain of SARS-CoV-2. These have been labeled variants of concern (VOCs). The reason for the increased transmissibility of some SARS-CoV-2 variants has not been fully determined, though it may be related to changes in receptor binding or viral load.

Clinical Reinfection

Reinfections have been confirmed to occur in several individuals through the detection of two different viral genomes associated with what appear to be separate episodes of infection. While these are rare, clinical reinfection of COVID-19 should be considered in a patient with a previously confirmed COVID-19 infection (as determined by a positive SARS-CoV-2 molecular test), who is experiencing a recurrence of COVID-19 symptoms and has a subsequent positive SARS-CoV-2 PCR test. This reinfection should include a sufficient time period between the first infection and the second (using clinical judgement and epidemiological investigation). As new variants are introduced, reinfection may become more common. Following infection, the majority of individuals will develop IgM and IgG antibodies within days to weeks of symptom onset. However, the relationship between antibody levels and the level of protection against reinfection remains unknown, as well as the role of cellular immunity in preventing reinfection (including cross-protective immunity following exposure to common coronaviruses). Fully vaccinated people who are admitted to hospital with COVID-19 should have genetic sequencing performed. All eligible individuals should be encouraged and enabled to be vaccinated.

As variants of concern (VOC) emerge in Canada it will be important to continue to assess patients with symptoms of COVID-19, particularly as breakthrough cases may occur amongst the vaccinated and those previously infected. There is still much more to learn about the SARS-CoV-2 virus, and it remains important that clinicians remind Canadians to remain steadfast in preventing the spread of COVID-19. This includes following appropriate public health precautions against infections such as physical distancing, observing regular hand hygiene, respiratory etiquette, mask wearing, environmental cleaning and disinfection, self-monitoring for symptoms compatible with COVID-19 and self-isolation when suspected to have or under investigation for COVID-19.

Acknowledgements

Dr. Marianna Ofner, Dr. Marina Salvadori, Yung-En Chung, Dr. Oliver Baclic, Dr. Cheryl Volling, Dr. James Brooks, Dr. Michael Green, Aidan Pucchio, Dr. Ewa Rajda and Dr. Guillaume Poliquin

Bibliography

Alene, M., Yismaw, L., Assemie, M.A., Ketema, D.B., Mengist, B., Kassie, B., & Birhan, T.Y. (2021). PLOS ONE Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis. https://doi.org/10.1371/journal.pone.0249090.

Argenziano M,G., Bruce S,L., Slater C.L., Tiao, J.R., Baldwin, M.R., Barr, R.G., Barr 4., …, Ruijun Chen. (2020). Characterization and Clinical Course of 1000 Patients with COVID-19 in New York: retrospective case series. BMJ 29(369),m1996. doi: 10.1136/bmj.m1996..

Auwaerter P.G. Coronavirus COVID-19 (SARS-CoV-2): Johns Hopkins ABX Guide. Coronavirus COVID-19 (SARS-CoV-2) | Johns Hopkins ABX Guide. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540747/all/Coronavirus_COVID_19__SARS_CoV_2_.

Bai, Y., Yao, L., Wei, T., Tian, F., Jin, D., Chen, L., & Wang, M. (2020). Presumed Asymptomatic Carrier Transmission of COVID-19. Jama 323(14):1406-1407. doi: 10.1001/jama.2020.2565.

Bullard, J., Dust, K., Funk, D., Strong, J.E., Alexander, D., Garnett, L., …Poliquin G. (2020). Predicting infectious SARS-CoV-2 from diagnostic samples. Clin Infect Dis 71(10):2663-2666. doi: 10.1093/cid/ciaa638.

Burke, R.M., Killerby, M.E., Newton, S., Ashworth; C.D., Berns, A.L., Brennan, S.,... Case Investigation Form Working Group. (2020). Symptom Profiles of a Convenience Sample of Patients with COVID-19 - United States, January-April 2020. MMWR Morb Mortal Wkly Rep, 69(28):904-908. doi: http://dx.doi.org/10.15585/mmwr.mm6928a2.

Cai, J., Xu, J., Lin, D., Zhi, Y., Lei, X., Zhenghai, Q., … Mei. Z. (2020). A Case Series of children with 2019 novel coronavirus infection: clinical and epidemiological features. Clin Infect Dis. 71(6):1547--1551. doi:10.1093/cid/ciaa198.

Casey, M., Griffin, J., McAloon, C.G., Byrne, A.W., Madden, J.M., McEvoy, D.,... More, S.J. (2020). Estimating pre-symptomatic transmission of COVID-19: a secondary analysis using published data. https://www.medrxiv.org/content/10.1101/2020.05.08.20094870v1.full.pdf

CDC Science Brief: Evidence used to update the list of underlying medical conditions that increase a person's risk of severe illness from COVID-19. Updated Mar. 29, 2021. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/underlying-evidence-table.html.

Chan, J.F., Yuan, S., Kok, K.H., To, K.K., Chu, H., Yang, J., …Hui, C.K. (2020). A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. Lancet, 395(10223):514-523. doi:https://doi.org/10.1016/S0140-6736(20)30154-9.

Chau, V.Q., Giustino, G., Mahmood, K.,Oliveros, E., Neibart, E., Oloomi, M., & Mancini, D.M. (2020). Cardiogenic shock and hyperinflammatory syndrome in young males with COVID-19. Circ Heart Fail, 13(10):e007485. doi: 10.1161/CIRCHEARTFAILURE.120.007485.

Centres for Effective Practice. COVID-19: Clinical Guidance for Primary Care Providers. https://tools.cep.health/tool/covid-19/#screening-covid19, Access: June 10, 2021.

Cevik, M., Tate, M., Lloyd, O., Maraolo, A.E., Schafers, J., & Ho, A. (2021). SARS-CoV-2, SARS-CoV, and MERS-CoV viral load dynamics, duration of viral shedding, and infectiousness: a systematic review and meta-analysis. The Lancet Microbe, 2(1), E13-E22. doi.org/10.1016/S2666-5247(20)30172-5.

Chen, N., Zhou, M., Dong, X., Qu. J., Gong, F., Han, Y., …Zhang, L. (2020). Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet, 395(10223):507-513.

Chen, L., Deng, C., Chen, X., Zhang, X., Chen, B., Yu, H., …Sun X. (2020). Ocular manifestations and clinical characteristics of 534 cases of COVID-19 in China: A cross-sectional study. Acta Ophthalmologica 98(8): 951-959.

Clerkin, K.J., Fried, J.A., Raikhelkar, J., Sayer, G., Griffin, J.M., Masoumi, A., …Uriel, N. (2020). Coronavirus Disease 2019 (COVID-19) and cardiovascular disease. Circulation,141(20):1648-1655. doi: 10.1161/CIRCULATIONAHA.120.046941.

Coronavirus Disease 2019 in Children - United States, February 12-April 2, 2020. (2020). MMWR Morb Mortal Wkly Rep, 69:422-426. doi: http://dx.doi.org/10.15585/mmwr.mm6914e4.

COVID-19 Scientific Advisory Group-Alberta. Rapid Evidence Report©2020, Alberta Health Services, August 21, 2020 COVID-19 Scientific Advisory Group Topic: What risk factors (such as age, medical conditions, or lifestyle factors) are associated with the development of severe outcomes in COVID-19? https://www.albertahealthservices.ca/assets/info/ppih/if-ppih-covid-19-sag-risk-factors-for-severe-covid-19-outcomes-rapid-review.pdf

Dadamo, H., Yoshikawa, T., & Ouslander, J.G. (2020). Coronavirus Disease 2019 in geriatrics and long-term care: The ABCDs of COVID-19. J Am Geriatr Soc, 68(5); 912-917. doi.org/10.1111/jgs.16445.

De Giorgi, F., Fabbian, F., Greco, S., Di Simone, E., De Giorgio, R., Passaro, A., …COMorbidity Evaluation of INTernal MEDicine COVID19 (OUTCOME-INTMED-COV19) Study Collaborators. (2020). Prediction of in-hospital mortality of patients with SARS-CoV-2 infection by comorbidity indexes: an Italian internal medicine single center study Eur Rev Med Pharmacol Sci., 24(19), 10258-10266.

Dominguez-Ramirez, L., Rodriguez-Perez, F., Sosa-Jurado, F., Santos-Lopez, G. & Cortes-Hernandez, P. (2020). The role of metabolic comorbidity in COVID-19 mortality of middle-aged adults. The case of Mexico. medRxiv 2020.12.15.20244160; doi: 10.1101/2020.12.15.20244160.

Dong, Y., Mo, X., Hu, Y., Qi, X., Jiang, F., Jiang, Z. & Tong, S. (2020). Epidemiology of COVID-19 Among Children in China. Pediatrics 145(6): e20200702.

Eliezer, M., Hautefort, C., Hamel, A., Verillaud, B., Herman, P., Houdart, E. & Eliot C. (2020). Sudden and complete olfactory loss function as a possible symptom of COVID-19. JAMA Otolaryngol Head Neck Surg, 146(7):674-675.

Feldstein, L.R., Tenforde, M.W., Friedman, K.G., Newhams, M., Rose, E.B., Dapul, H., … for the Overcoming COVID-19 Investigators. (2021). Characteristics and Outcomes of US Children and Adolescents With Multisystem Inflammatory Syndrome in Children (MIS-C) Compared With Severe Acute COVID-19. JAMA, 325(11):1074-1087. doi:10.1001/jama.2021.2091.

Flodgren, G.M. (2020). Immunity after SARS-CoV-2 infection, 1st update - a rapid review. Oslo: Norwegian Institute of Public Health, 2020. https://www.fhi.no/en/publ/2020/Immunity-after-SARS-CoV-2-infection-1st-update/.

Fu, L., Bingyi, W., Yuan, T., Chen, X., Ao, Y. Fitzpatric, T.,... Zou, H. (2020). Clinical characteristics of coronavirus disease 2019 (COVID-19) in China: a systematic review and meta-analysis. J Infect, 80(6):656-665.

Gates, M., Pillay, J., Wingert, A., Guitard, S., Rahman, S., Zakher, B.,... Hartling, L. (2021). Risk factors associated with severe outcomes of COVID-19: An updated rapid review to inform national guidance on vaccine prioritization in Canada. medRxiv. https://doi.org/10.1101/2021.04.23.21256014.

Gold, J.A.W., Wong, K.K., Szablewskiet, C.M., Patel, P.R., Rossaw, J., da Silva, J., …Jackson, B.R. (2020). Characteristics and Clinical Outcomes of Adult Patients Hospitalized with COVID-19 - Georgia, March 2020. MMWR Morb Mortal Wkly Rep. 2020. 69(18);545-550.

Götzinger, F., Santiago-García, B., Noguera-Julián, A., Lanaspa, M., Lancella, L., Carducci, F.I.C.,... ptbnet COVID-19 Study Group. (2020). COVID-19 in Children and Adolescents in Europe: A Multinational, Multicentre Cohort Study. Lancet Child Adolesc Health, 4(9):653-661. doi:10.1016/S2352-4642(20)30177-2.

Goyal, P., Choi, J.J., Pinheiro, L.C., Schenck, E.J., Chen, R., Jabri, A., …Safford, M.M. (2020). Clinical characteristics of Covid-19 in New York City. N Engl J Med, 382:2372-2374. doi: 10.1056/NEJMc2010419NEJMc2010419.

Grant, M.C., Geoghegan, L., Arbyn, M., Mohammed, A., McGuinness, L., Clarke, E.L., & Wade, R.G. (2020). PLOS ONE The prevalence of symptoms in 24,410 adults infected by the novel coronavirus (SARS-CoV-2; COVID-19): A systematic review and meta-analysis of 148 studies from 9 countries. Published: June 23, 2020. https://doi.org/10.1371/journal.pone.0234765.

Grifoni, A., Weiskopf, D., Ramirez, S.I., Mateus, J., Dan, J.M., Rydyznski-Moderbacher, C., …Sette, A. (2020). Targets of T Cell Responses to SARS-CoV-2 Coronavirus in Humans with COVID-19 Disease and Unexposed Individuals. Cell, 181(7):1489-1501.e15. doi: 10.1016/j.cell.2020.05.015.

Guan, W.J., Ni, Z.Y., Hu, Y., Liang, W., Ou, C., He, J., …China Medical Treatment Expert Group for Covid-19. (2020). Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med, 382:1708-1720. doi: 10.1056/NEJMoa2002032.

Havers, F.P., Reed, C., Lim, T., Montgomery, J.M., Klena, J.D., Hall, A.J., … Krapiunaya, I. (2020). Seroprevalence of antibodies to SARS-CoV-2 in 10 sites in the United States, March 23-May 12, 2020. JAMA Intern Med, 180(12):1576-1586. doi:10.1001/jamainternmed.2020.4130

He, X., Lau E.H.Y., Wu, P., Deng, X., Wang, J., Yiu, X.H., …Leung, G.M. (2020). Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med 26, 672-675. https://doi.org/10.1038/s41591-020-0869-5.

Hoehl, S., Rabenau, H., Berger, A., Kortenbusch, M., Cinatl, J., Bojkova, D., …Ciesek, S. (2020). Evidence of SARS-CoV-2 Infection in Returning Travelers from Wuhan, China. N Engl J Med, 382(13):1278-1280. doi: 10.1056/NEJMc2001899.

Hu, Z., Song, C., Xu, C., Jin, G,. Chen, Y., Xu, X., …, Shen, H. (2020). Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. Sci China Life Sci, 63(5):706-711. doi: 10.1007/s11427-020-1661-4.

Huang, C., Wang, Y., Li, X., Ren, L., Zhao, J., Hu, Y., …Cao, B. (2020). Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 15;395(10223):497-506. doi: 10.1016/S0140-6736(20)30183-5.

Irfan, O., Muttalib, F., Tang, K., Jiang, L., Lassi, Z.S., Bhutta, Z.,... Lassi, Z.S. (2021). Clinical characteristics, treatment and outcomes of paediatric COVID-19: a systematic review and meta-analysis. Arch Dis Child, 106(5):440-448. doi: 10.1136/archdischild-2020-321385.

Jarrett, P.G., Rockwood, K., Carver, D., Stolee, P., & Cosway, S. (2020). Illness presentation in elderly patients. Arch Intern Med,1995;155(10):1060-4.

Jung, Y.J., Yoon, J.L., Kim, H.S., Lee, A.Y., Kim, M.Y., & Cho, J.J. (2017). Atypical clinical presentation of geriatric syndrome in elderly patients with pneumonia or coronary artery disease. Ann of Geri Med and Res, 21(4):158-63. 2.

Jones, T.C., Mühlemann, B., Veith, T., Biele, G., Zuchowski, M., Hofmann, J., … Drosten, C. (2021). An analysis of SARS-CoV-2 viral load by patient age. Science eabi5273. DOI: 10.1126/science.abi5273doi:10.1101/2020.06.08.20125484.

Kam, K.Q., Yung, C.F., Cui, L., Lin, R.T.P., Mak, T.M., Maiwald, M., …Thoon, K.C. (20220). A Well Infant with Coronavirus Disease 2019 (COVID-19) with High Viral Load. Clin Infect Dis, 71(15):847-849. doi: 10.1093/cid/ciaa201.

Kimball, A., Hatfield, K.M., Arons, M., James, A., Taylor, J.,Spicer, K.,... CDC COVID-19 Investigation Team. (2020). Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility - King County, Washington, March 2020. MMWR. 69:377-81. doi:10.15585/mmwr.mm6913e1

Kumar, A., Arora, A., Sharma, P., Anikhindi, S. A., Bansal, N., Singla, V.,... Srivastava, A. (2020). Clinical features of covid-19 and factors associated with severe clinical course: A systematic review and meta-analysis. SSRN Electronic Journal. doi:10.2139/ssrn.3566166.

Lauer, S. A., Grantz, K. H., Bi, Q., Jones, F. K., Zheng, Q., Meredith, H. R.,... Lessler, J. (2020). The incubation period of Coronavirus DISEASE 2019 (COVID-19) from publicly REPORTED Confirmed Cases: Estimation and application. Annals of Internal Medicine, 172(9), 577-582. doi:10.7326/m20-0504.

Lechien, J.R., Chiesa-Estomba, C.M., Place, S., Laethem, Y.V., Cabaraux, P., Mat, Q.,... COVID-19 Task Force of YO-IFOS. (2020). Clinical and epidemiological characteristics of 1,420 European patients with mild-to-moderate coronavirus disease 2019. J Intern Med, 288(3):335-344. doi: 10.1111/joim.13089.

Li, L.Q., Huang, T., Wang, Y.Q., Wang, Z.P., Liang, Y., Huang, T.B.,... Wang, Y. (2020). COVID-19 novel coronavirus patients' clinical characteristics, discharge rate and fatality rate of meta-analysis. J Med Virol, 92(6):577-583.doi:10.1002/jmv.25757.

Li, Q., Guan, X., Wu, P., Wang, X., Zhou, L., Tong, Y.,... Feng, Z. (20220). Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus-Infected Pneumonia. N Engl J Med 2020; 382:1199-207.

Li, R., Pei, S., Chen, B., Song, Y., Zhang, T., Yang, W., & Shaman, J. (2020). Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2). Science, 368(6490), 489-493. doi.org/10.1126/science.abb3221.

Lippi, G., & Plebani, M. (2020). Laboratory abnormalities in patients with COVID-2019 infection. Clin Chem Lab Med, 58(7):1131-1134. doi: 10.1515/cclm-2020-0198.

Liguoro, I., Pilotto, C., Bonanni. M., Ferrari, M.E., Pusiol, A., Nocerino, A., … Cogo, P. E., (2020). SARS-CoV-2 Infection in Children and Newborns: A Systematic Review. Eur J Pediatr, 1-18. doi: 10.1007/s00431-020-03684-7 2020. doi:10.21203/rs.3.rs-24629/v1.

Lovato, A.m & de Filippis, C. (2020). Clinical Presentation of COVID-19: A Systematic Review Focusing on Upper Airway Symptoms. Ear Nose Throat J, 99(9):569-576. doi: 10.1177/0145561320920762.

Lu, X., Zhang, L., Du, H., Zhang, J., Li, Y.Y., Qu, J.,... the Chinese Pediatric Novel Coronavirus Study Team. (20220.) SARS-CoV-2 Infection in Children. N Engl J Med, 23;382:1663-1665. doi:10.1056/NEJMc2005073.

Magro, C., Mulvey, J.J., Berlin, D., Nuovo, G., Salvatore, S., Harp.,... Laurence, J. (2020). Complement associated microvascular injury and thrombosis in the pathogenesis of severe COVID-19 infection: a report of five cases. Transl Res, 220:1-13. doi: 10.1016/j.trsl.2020.04.007

Malone, M.L., Hogan, T.M., Perry, A., Biese, K., Bonner, A., Pagel, P., & Unroe, K.T. (2020). COVID-19 in older adults - Key points for emergency department providers. J of Geri Emerg Med, 1(4):1-11. 5.

Mannheim, J., Gretsch, S., Layden, J.E., & Fricchione, M.J. (2020). Characteristics of Hospitalized Pediatric Coronavirus Disease 2019 Cases in Chicago, Illinois, March-April 2020. J Pediatric Infect Dis Soc, 9(5):519-522. doi:10.1093/jpids/piaa070.

McMichael, T.M., Clark, S., Pogosjans, S., Kay, M., Lewis, J., Baer, A.,... and CDC COVID-19 Investigation Team. (2020). COVID-19 in a Long-Term Care Facility - King County, Washington, February 27-March 9, 2020. MMWR Morbidity and mortality weekly report, 69(12):339-342.

Mizumoto, K., Kagaya, K., Zarebski, A., & Chowell, G. (2020). Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020. Euro surveillance: bulletin Europeen sur les maladies transmissibles - European communicable disease bulletin, 25(10).

Morris, S.B., Schwartz, N.G., Patel, P., Abbo, L., Beauchamps, L., Balan, S., & Godfred-Cato, S. (2020). Case Series of Multisystem Inflammatory Syndrome in Adults Associated with SARS-CoV-2 Infection - United Kingdom and United States, March-August 2020. MMWR Weekly, 69(40);1450-1456. doi: dx.doi.org/10.15585/mmwr.mm6940e1.

National COVID-19 Clinical Evidence Taskforce. Caring for people with COVID-19. Supporting Australia's healthcare professionals with continually updated, evidence-based clinical guidelines. 10/06/21: Weekly Communique from the National Steering Committee. https://covid19evidence.net.au/.

Oran, D.P, & Topol, E.J. (2020). Prevalence of Asymptomatic SARS-CoV-2 Infection. Ann Intern Med, 173:362-367. doi:10.7326/M20-3012.

Oxley, T.J., Mocco, J., Majidi, S., Kellner, C.P., Shoirah, H., Singh, I.P.,... Fifi, J.T. (2020). Large-vessel stroke as a presenting feature of Covid-19 in the young. N Engl J Med, 382:e60. doi: 10.1056/NEJMc2009787.

Pan, L., Mu, M., Yang, P., Sun, Y., Wang, R., Yan, J.,... Tu, L. (2020). Clinical characteristics of COVID-19 patients with digestive symptoms in Hubei, China: a descriptive, cross-sectional, multicenter study. Am J Gastroenterol, 115(5): 766-773. doi: 10.14309/ajg.0000000000000620.

Pan, X., Chen, D., Xia, Y., Wu, X, Li, T., Ou, X.,... Liu, J. (2020). Asymptomatic cases in a family cluster with SARS-CoV-2 infection. Lancet Infect Dis, 20(4):410-411. doi:10.1016/S1473-3099(20)30114-6.

Poline, J., Gaschignard, J., Leblanc, C., Madhi, F., Foucaud, E., Nattes, E.,... Ouldali, N. (2020). Systematic Severe Acute Respiratory Syndrome Coronavirus 2 Screening at Hospital Admission in Children: A French Prospective Multicenter Study. Clin Infect Dis, ciaa1044. doi: 10.1093/cid/ciaa1044.

Qian G, Yang N, Ma AHY, Wang, L., Li, G., Chen, X., & Chen, X. (2020). A COVID-19 Transmission within a family cluster by presymptomatic infectors in China. Clin Infect Dis, 71(15):861-862. doi: 10.1093/cid/ciaa316.

Riphagen, S., Gomez, X., Gonzalex-Martinez, C., Wilkinson, N., & Theocharis, P. (2020). Hyperinflammatory shock in children during COVID-19 pandemic Lancet, Volume 395, Issue 10237, P1607-1608, May 23, 2020. doi: https://doi.org/10.1016/S0140-6736(20)31094-1.

Rodriguez-Morales, A.J., Cardona-Ospina, J.A., Gutiérrez-Ocampo E, Villamizar-Peña, R., Holguin-Rivera, Y., Escalera-Antezana, J.P.,... Latin American Network of Coronavirus Disease 2019-COVID-19 Research (LANCOVID-19). (2020). Clinical, laboratory and imaging features of COVID-19: a systematic review and meta-analysis. Travel Med Inf Dis, 34:101623. doi: 10.1016/j.tmaid.2020.101623.

Rosenberg, E.S., Tesoriero, J.M., Rosenthal, E.M., Chung, R., Barranco, M.A., Styer, L.M.,... Zucker, H.A. (2020). (2020). Cumulative incidence and diagnosis of SARS-CoV-2 infection in New York. Ann Epidemiol., 48:23-29. doi:10.1016/j.annepidem.2020.06.004.

Rosenthal, N., Cao, Z., Gundrum, J., Sianis, J., & Safo, S. (2020). Risk Factors Associated with In-Hospital Mortality in a US National Sample of Patients With COVID-19. JAMA Netw Open, 3(12):e2029058. doi:10.1001/jamanetworkopen.2020.29058.

Rothe, C., Schunk, M., Sothmann, P., Bretzel, G., Froeschl, G., Wallrauch, C.,... Hoelscher, M. (2020). Transmission of 2019-nCoV Infection from an Asymptomatic Contact in Germany. N Engl J Med, 382:970-971. doi: 10.1056/NEJMc2001468.

Roxby, A.C., Greninger, A.L., Hatfield, K.M., Lynch, J.B., Dellit, T.H., James, A.,... Neme, S. (2020). Detection of SARS-CoV-2 Among Residents and Staff Members of an Independent and Assisted Living Community for Older Adults -- Seattle, Washington, 2020. MMWR, 69(14):416-418. doi:10.15585/mmwr.mm6914e2.

Shekerdemian, L.S., Mahmood, N.R., Wolfe, K.K., Riggs, B.J., Ross, C.E., McKiernan, C.A.,... the International COVID-19 PICU Collaborative. (2020). Characteristics and Outcomes of Children With Coronavirus Disease 2019 (COVID-19) Infection Admitted to US and Canadian Pediatric Intensive Care Units. JAMA Pediatr, 174(9):868-873. doi:10.1001/jamapediatrics.2020.1948.

Shi, H., Han, X., Jiang, N., Cao, Y., Alwalid, O., Gu, J., Fan, Y., & Zheng, C. (2020). Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis, 20(4):425-434.

Soresina, A., Moratto, D., Chiarini, M., Paolillo, C., Baresi, G., Focà, E.,... Badolato, R. (2020). Two X‐linked agammaglobulinemia patients develop pneumonia as COVID‐19 manifestation but recover. Pediatr Allergy Immunol, 31(5):565-569. doi: 10.1111/pai.13263.

Spinato, G., Fabbris, C., Polesel, J., Cazzador, D., Borsetto, D., Hopkins, C., & Boscolo-Rizzo, P. (2020). Alterations in Smell or Taste in Mildly Symptomatic Outpatients With SARS-CoV-2 Infection. JAMA, 323(20):2089-2090. doi:10.1001/jama.2020.6771.

Sun, L., Shen, L., Fan, J., Gu, F., Hu, M., An, Y.,... Bi, J. (2020). Clinical Features of Patients with Coronavirus Disease 2019 (COVID‐19) from a Designated Hospital in Beijing, China. J Med Virol, 92(10):2055-2066. doi: 10.1002/jmv.25966.

Teherani, M.F., Kao, C.M., Camacho-Gonzalez, A., Banskota, S., Shane, A.L., Linam, W.M., & Jaggi, P. (2020). Burden of Illness in Households With Severe Acute Respiratory Syndrome Coronavirus 2-Infected Children. J Pediatric Infect Dis Soc, 9(5):613-616. doi:10.1093/jpids/piaa097.

Tillett, R.L., Sevinsky, J.R., Hartley P.D., Kerwin, H., Crawford, N., Gorzalski, A.,... Pandori, M. (2021). Genomic Evidence for a Case of Reinfection with SARS-CoV-2 Lancet Infect Dis, 21: 52-55. doi.org/10.1016/S1473-3099(20)30764-7.

To, K. K., Hung, I. F., Ip, J. D., Chu, A. W., Chan, W., Tam, A. R.,... Yuen, K. (2020). Coronavirus Disease 2019 (COVID-19) Re-infection by a Phylogenetically Distinct Severe Acute Respiratory Syndrome Coronavirus 2 Strain Confirmed by Whole Genome Sequencing. Clinical Infectious Diseases. doi:10.1093/cid/ciaa1275.

To, K.K., Tsang, O.T., Leung, W.S., Tam, A.R., Wu, T., Lung, D.C.,... Yuen, K. (2020). Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study. Lancet Infect Dis., 20(5):565-574. doi:10.1016/S1473-3099(20)30196-1.

Tong, Z.D., Tang, A., Li, K.F., Li, P., Wang, H., Yi, J.,... Yan, J. (2020). Potential Presymptomatic Transmission of SARS-CoV-2, Zhejiang Province, China, 2020. Emerg Infect Dis, 26(5):1052-1054. doi:10.3201/eid2605.200198.

Verdoni, L., Mazza, A., Gervasoni, A., Martelli, L., Ruggeri, M., Ciuffreda, M.,... D'Antiga, L; (2020.) An outbreak of severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an observational cohort study. Lancet, 395(10239), 1771-1778. doi: https://doi.org/10.1016/S0140-6736(20)31103-X.

Viner, R.M., Ward, J.L., Hudson, L.D., Ashe, M., Patel, S.V., Hargreaves, D., & Whittaker, E. (2020). Systematic review of reviews of symptoms and signs of COVID-19 in children and adolescents. Arch Dis Child. archdischild-2020-320972. doi: 10.1136/archdischild-2020-320972.

Wang, D., Hu, B., Hu, C., Zhu, F., Liu, X., Zhang, J.,... Peng, Z. (2020). Clinical Characteristics of 138 Hospitalized Patients with 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA, 323(11): 1061-1069. doi:10.1001/jama.2020.1585.

Wang, X., Zhou, Q., He, Y., Liu, L., Ma., X, Wei, X.,... Gao, Z. (2020). Nosocomial Outbreak of 2019 Novel Coronavirus Pneumonia in Wuhan, China. Eur Respir J, 55(6):2000544. doi: 10.1183/13993003.00544-2020.

Wang, Y., Liu, Y., Liu, L., Wang, X., Luo, N., & Ling, L. (2020). Clinical outcome of 55 asymptomatic cases at the time of hospital admission infected with SARS-Coronavirus-2 in Shenzhen, China. J Infect Dis, 221(11):1770-1774. doi: 10.1093/infdis/jiaa119.

Wei, M., Yuan, J., Liu, Y., Fu, T., Yu, X., & Zhang, Z.J. (2020). Novel Coronavirus Infection in Hospitalized Infants Under 1 Year of Age in China. JAMA, 323(13):1313-1314. doi:10.1001/jama.2020.2131.

Wei, W.E., Li, Z., Chiew, C.J., Yong, S.E., Toh, M.P., & Lee, V.J. (2020). Presymptomatic Transmission of SARS-CoV-2 - Singapore, January 23--March 16, 2020. MMWR, 69:411-5. doi:10.15585/mmwr.mm6914e1.

Williamson, E.J., Walker, A.J., Bhaskaran, K., Bacon, S., Bates, C., Morton, C.E.,... Goldacre, B. (2020). Factors associated with COVID-19-related death using OpenSAFELY. Nature, 584(7821):430-436. doi: 10.1038/s41586-020-2521-4.

Wölfel, R., Corman, V.M., Guggemos, W., Seilmaier, M., Zange, S., Müller, M.A.,... Wendtner, C. (2020). Virological assessment of hospitalized patients with COVID-2019. Nature, 581(7809):465-469. doi:10.1038/s41586-020-2196-x.

Wu, C., Chen, X., Cai, Y., Xia, J., Zhou, X., Xu, S.,... Song, Y. (2020). Risk Factors Associated with Acute Respiratory Distress Syndrome and Death in Patients With Coronavirus Disease 2019 Pneumonia in Wuhan, China. JAMA Intern Med., 2020 Mar 13; e200994.

Wu, Z., McGoogan, J.M. Characteristics of and Important Lessons from the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72314 Cases from the Chinese Center for Disease Control and Prevention. JAMA Intern Med, 180(7):934-943. doi:10.1001/jamainternmed.2020.0994.

Wu. L., Wang, N., Chang, Y., Tian, X., Na, D., Zhang.,... Liang, G. (2007). Duration of antibody responses after severe acute respiratory syndrome. Emerg Infect Dis. 2007;13(10):1562-1564. doi:10.3201/eid1310.070576.

Xu, X., Wu, X., Jiang, X., Xu, J., Ying, L., Ma, C.,... Li, L. (2020). Clinical findings in a group of patients infected with the 2019 novel coronavirus (SARS-Cov-2) outside of Wuhan, China: retrospective case series. BMJ, 368:m606. doi: https://doi.org/10.1136/bmj.m606.

Yahav, D., Yelin, D., Eckerle, I., Eberjardt, C.S., Wang, J., Cao, B., & Kaiser, L. (2021). Definitions for coronavirus disease 2019 reinfection, relapse and PCR re-positivity. Clin Microbiol Infect, 27(3): 315-318. doi: 10.1016/j.cmi.2020.11.028.

Yang, J., Zheng, Y., Gou, X., Pu, K., Chen, Z., Guo, Q.,... Zhou, Y. (2020). Prevalence of Comorbidities and Its Effects in Patients Infected With SARS-CoV-2: A Systematic Review and Meta-Analysis. Int J Infect Dis, 94:91-95. doi: 10.1016/j.ijid.2020.03.017.

Yang, X., Yum Y., Xu, J., Shu, H., Xia, J., Liu, H.,... Shang, Y. (2020). Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study. The Lancet Respiratory Medicine, 8(5):475-481. doi:https://doi.org/10.1016/S2213-2600(20)30079-5.

Yasuhara, J., Watanabe, K., Takagi, H., Sumitomo, & N., Kuno, T. (2020). COVID-19 and multisystem inflammatory syndrome in children: A systematic review and meta-analysis. Pediatr Pulmonol, 55(10):2565-2575. doi: 10.1002/ppul.24991.

Young, B.E., Ong, S.W.X., Kalimuddin, S., Low, J.G., Tan, S.Y., Loh, J.,... the Singapore 2019 Novel Coronavirus Outbreak Research Team. (2020). Epidemiologic Features and Clinical Course of Patients Infected With SARS-CoV-2 in Singapore. JAMA, 323(15):1488-1494. doi:10.1001/jama.2020.3204.

Zhao, J., Yuan, Q., Wang, H., Liu, W., Liao, X., Su, Y.,... Zhang, Z. (2020). Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clin Infect Dis, 71(16):2027-2034. doi: 10.1093/cid/ciaa344.

Zhou, F., Yu, T., Du, R., Fan, G., Liu, Y., Liu, Z.,... Cao, B. (2020). Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. The Lancet 395(10229):1054-1062. doi:10.1016/s0140-6736(20)30566-3.

Zhu, J., Pan., J., Pang, J., Zhong, Z., Li, H., He, C.,... Zhao, C. (2020). Clinical characteristics of 3,062 COVID-19 patients: a meta-analysis. J Med Virol, 92(10):1902-1914. doi: 10.1002/jmv.25884.

Zimmermann, P., & Curtis, N. (2020). COVID-19 in Children, Pregnancy and Neonates. The Pediatric Infectious Disease Journal, 39(6):469-477. doi:10.1097/inf.0000000000002700.

Zou, L., Ruan, F., Huang, M., Liang, L., Huang, H., Hong, Z.,... Wu, J. (2020). SARS-CoV-2 Viral Load in Upper Respiratory Specimens of Infected Patients. N Engl J Med, 382:1177-1179. doi: 10.1056/NEJMc2001737.

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