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Whooping cough (pertussis): For health professionals

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Key information

Pertussis is a highly contagious infection of the respiratory tract caused by the bacterium Bordetella pertussis. Pertussis is endemic both in Canada and internationally. It is a nationally notifiable disease.

The disease is characterized by a paroxysmal cough and inspiratory whoop, with 3 clinical stages:

  1. catarrhal
  2. paroxysmal
  3. convalescent

The bacteria spreads through infectious respiratory particles and rarely, through contact with contaminated fomites.

From time to time, there have been increases in pertussis cases in Canada. Overall, however, the number of cases has declined since pertussis vaccination programs were introduced.

Vaccination against pertussis is the most effective means of prevention. However, a decline in protection has been observed over time due to waning immunity. Routine booster doses are recommended. Infants and children are at the highest risk for contracting the disease, experiencing complications and even death.

The National Advisory Committee on Immunization (NACI) recommends routine immunization against pertussis for infants, children, adolescents and adults, including for pregnant individuals in each pregnancy.

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Epidemiology

Bordetella pertussis is a gram-negative aerobic bacterium. Pertussis is a toxin-mediated disease, which means that various toxins produced by the bacteria are responsible for most of its clinical features.

Reservoir

Humans are the only reservoir.

Incubation period

The incubation period for pertussis is 5 to 10 days (with a range of 4 to 21 days).

Transmission

Pertussis is very contagious. Studies show an 80% secondary attack rates among susceptible household contacts.

Pertussis is transmitted through:

Infectiousness is greatest during the catarrhal stage.

In general, a person should be considered infectious from when symptoms began to about 2 weeks after coughing begins, if not treated with antibiotics. A person is no longer considered contagious after 5 days of appropriate antibiotic treatment.

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Clinical manifestations

The clinical course of pertussis is divided into 3 stages:

  1. catarrhal
  2. paroxysmal
  3. convalescent

Symptoms in the initial catarrhal stage may begin 5 to 10 days after infection (up to 21 days). This first stage is an upper respiratory infection characterized by:

After 1 to 2 weeks of a gradually worsening cough, the paroxysmal stage (second stage) begins.

This second stage is characterized by:

The paroxysmal stage typically lasts 1 to 6 weeks, but can last up to 10 weeks.

In the convalescent stage (third stage), recovery is gradual and may take weeks to months.

The clinical course varies with age. In young infants, who are at the highest risk of complications, clinical symptoms are frequently atypical. The whooping sound and post-tussive vomiting may be absent. The presentation may be characterized solely by episodes of apnea.

Pertussis may be milder in adolescents and adults, with no symptoms to a very prolonged, debilitating cough. Pertussis is a common and often unrecognized cause of cough persisting for over 2 weeks in adolescents and adults.

Hear the sound of whooping cough:

Source: PKIDs (Parents of Kids with Infectious Diseases)

Complications

Serious complications occur mainly in infants younger than 1 year old. About 30% of this age group who get infected are hospitalized.

Complications of pertussis can include:

Adolescents and adults with persistent coughing can also have:

Pertussis can be fatal, especially for infants under 1 year of age.

Risk factors

Pertussis can affect anyone. However, severity is greatest among infants who are not immunized or are under immunized.

As immunity to pertussis from childhood vaccination and disease wanes with time, adolescents and adults are at risk of infection and transmitting the disease to others.

It’s important that people stay up-to-date with recommended routine vaccination throughout their lifetime.

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Diagnosis and laboratory testing

Pertussis should be suspected in those presenting clinically with:

Diagnosis should be confirmed with a laboratory sample. This can include a nasopharyngeal swab or nasopharyngeal aspirate for polymerase chain reaction (PCR) test.

Health care providers are required to report suspected cases of pertussis to their local public health unit or office, as pertussis is a nationally notifiable disease.

Only cases meeting the national case definition are reported to the Canadian Notifiable Disease Surveillance System.

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Treatment

Early treatment with antibiotics is the most effective for reducing symptom severity, ideally given within 2 weeks of the onset of symptoms.

People with pertussis are no longer considered contagious after 5 days of appropriate antibiotic treatment.

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Prevention

Routine vaccination

Vaccination against pertussis is the most effective means of prevention. The vaccine effectiveness following the primary series with acellular pertussis vaccines is estimated to be about 85%, and about 90% following booster immunization. However, a progressive decline in protection has been observed following the second booster dose (usually given between 4 and 6 years of age). For this reason, additional doses are recommended.

Primary immunization with a pertussis-containing vaccine for all children is recommended at 2, 4, 6 and generally 18 months of age. Booster doses are recommended at 4 to 6 years and 14 to 16 years of age.

One dose of acellular pertussis-containing vaccine (Tdap) vaccine should be administered to adults if they haven’t previously received a pertussis vaccine at 18 years of age or older. Vaccination schedules may vary depending on your province or territory.

There are currently several approved pertussis-containing vaccines in Canada. The combination vaccine in infants may also include hepatitis B, inactivated polio virus or Haemophilus influenzae type b. The acellular pertussis-containing vaccine is given to adults in combination with diphtheria and tetanus.

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Immunization for pregnant individuals

Pertussis vaccination should be offered to every pregnant individual, in every pregnancy.

Immunization during pregnancy is ideally recommended at 27 to 32 weeks of gestation, in every pregnancy. However, pertussis vaccine can be given at any time in the pregnancy.

Vaccinating pregnant individuals:

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Catch-up and accelerated schedules

If required, the first dose of age-appropriate pertussis containing vaccine can be given as early as 6 weeks. The next 2 doses may be given at intervals of 4 weeks.

The fourth dose is usually given 12 months after the third dose.

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Adverse events and contraindications

Expected reactions of pertussis-containing vaccines authorized in Canada are usually mild and resolve on their own. Mild reactions can occur soon after vaccination and may include:

Less common, serious adverse events after vaccination can also occur.

To ensure the ongoing safety of vaccines in Canada, it’s critical that vaccine providers and other clinicians report adverse events following immunization (AEFI). In most jurisdictions, reporting may also be mandatory under the public health legislation. Vaccine providers are to report AEFIs through their local public health unit or office and to check for specific AEFI reporting requirements in their province or territory.

There are circumstances where pertussis vaccination may be contraindicated, such as in persons with a history of anaphylaxis after a previous vaccine.

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Post-exposure and outbreak management

Cases of pertussis should be reported to the local public health unit or office.

Confirmed and suspected cases should be isolated from young children and infants until the case has received at least 5 days of appropriate antibiotics.

Suspected cases who do not receive antibiotics should be isolated (for example, not go to school, work or other public places) for 3 weeks after onset of paroxysmal cough or until the end of cough, whichever comes first. This includes avoiding close contact with others, especially when around others who are at risk of more severe disease or outcomes (for example, infants, pregnant individuals and people who are immunocompromised).

To help stop the spread, individuals with pertussis should use personal protective measures, which may include:

Contacts, especially children, must have their immunization status verified. If immunization status is incomplete and no contraindications are identified, recommended doses of pertussis-containing vaccine should be given.

Specific disease management and control guidelines may be available at the provincial, territorial or local level.

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Surveillance and monitoring

Surveillance systems to monitor pertussis in Canada

Pertussis has been a nationally notifiable disease in Canada since 1924.

Cases that meet the national case definition of pertussis get reported to the Public Health Agency of Canada (PHAC) for national monitoring purposes. Health care providers and laboratories report cases to their local public health unit or office. These reports are forwarded to provincial and territorial public health officials, and then to PHAC through the Canadian Notifiable Disease Surveillance System.

As well, the Immunization Monitoring Program, ACTive (IMPACT), a pediatric hospital-based active surveillance system supported by PHAC, monitors pediatric pertussis hospitalizations.

Pertussis epidemiology and immunization in Canada

Pertussis is endemic and cyclical in Canada, with peaks at intervals of 2 to 5 years.

The incidence of pertussis decreased significantly after the whole cell pertussis vaccine was introduced in 1943, acellular vaccines in 1997 and 1998, and an adolescent dose in 2004. The average incidence of 156 cases per 100,000 population in the 5 years before a vaccine was introduced (1938 to 1942) decreased to a low of 2.3 cases per 100,000 population between 2019 and 2023 (Figure 1).

In 2018, NACI recommended a dose of tetanus-diphtheria-acellular pertussis vaccination be given to pregnant individuals in each pregnancy.

Before the COVID-19 pandemic, between 600 and 5,000 people in Canada tested positive for pertussis every year. Like many other diseases that spread between people, record low numbers of pertussis infections were reported between 2020 and 2022, when public health measures were in place to reduce the spread of COVID-19.

Pertussis case counts returned to usual levels in 2023. However, there have been reports of high pertussis case counts in parts of Canada in 2024 and 2025, indicating an increase greater than typical cyclic peaks.

The incidence of pertussis is highest in infants and children and generally decreases in older age groups (Figure 2).

The highest age-specific mean annual incidence rates from 2019 to 2023 were:

Figure 1. Reported cases and incidence rate (per 100,000 population) of pertussis in Canada by year, 1924 to 2023

figure 1

Figure 1: Text description
Year Cases Incidence rate (per 100,000 population)
1924 6,377 70.5
1925 7,218 78.5
1926 6,968 74.5
1927 6,691 70.2
1928 6,650 68.3
1929 10,536 105.2
1930 11,747 115.2
1931 9,174 88.5
1932 12,058 114.9
1933 14,622 137.7
1934 19,484 181.6
1935 17,991 166.1
1936 16,256 148.7
1937 17,396 157.7
1924 6,377 70.5
1938 16,003 143.7
1939 17,972 159.8
1940 19,878 174.9
1941 16,647 144.9
1942 18,384 158.0
1943 19,082 162.0
1944 12,384 103.8
1945 12,192 101.1
1946 7,671 62.5
1947 10,324 82.4
1948 7,084 55.3
1949 7,961 59.3
1950 12,182 89.0
1951 8,889 63.6
1952 8,520 59.0
1953 9,387 63.3
1954 11,600 76.0
1955 13,682 87.3
1956 8,513 52.9
1957 7,459 44.9
1958 6,932 40.6
1959 7,259 41.5
1960 5,993 33.6
1961 5,476 30.1
1962 8,076 43.5
1963 6,134 32.4
1964 4,844 25.1
1965 2,472 12.6
1966 4,555 22.8
1967 4,949 24.3
1968 2,505 12.1
1969 1,242 5.9
1970 2,098 9.9
1971 3,002 13.7
1972 1,297 5.8
1973 997 4.4
1974 1,579 6.9
1975 3,387 14.6
1976 3,002 12.8
1977 1,988 8.4
1978 2,666 11.1
1979 2,227 9.2
1980 2,873 11.7
1981 2,632 10.6
1982 2,314 9.2
1983 2,232 8.8
1984 1,353 5.3
1985 2,433 9.4
1986 2,557 9.8
1987 1,483 5.6
1988 1,301 4.9
1989 3,943 14.5
1990 8,330 30.1
1991 2,534 9.0
1992 3,763 13.2
1993 7,537 26.2
1994 10,116 34.8
1995 9,308 31.7
1996 5,230 17.6
1997 4,281 14.3
1998 8,896 29.4
1999 5,862 19.2
2000 4,748 15.4
2001 2,945 9.5
2002 3,199 10.2
2003 3,239 10.2
2004 3,104 9.7
2005 2,492 7.7
2006 2,346 7.2
2007 1,493 4.5
2008 1,967 5.9
2009 1,628 4.8
2010 750 2.2
2011 694 2.0
2012 4,653 13.4
2013 1,281 3.6
2014 1,531 4.3
2015 3,522 9.8
2016 3,951 10.9
2017 3,586 9.8
2018 1,467 3.9
2019 2,120 5.6
2020 584 1.5
2021 28 0.1
2022 184 0.5
2023 1374 3.6
Figure 2. Total number and average incidence rates (per 100,000 population) of reported pertussis cases in Canada, by age group, 2019 to 2023 (n=4,306)

figure 2

Figure 2: Text description
Age groups Total number of cases Average incidence rate (per 100,000 population)
Under 1 year 411 23.2
1 to 4 years 1000 13.2
5 to 9 years 867 8.5
10 to 14 years 758 7.3
15 to 19 years 264 2.5
20 to 24 years 141 1.1
25 to 29 years 116 0.9
30 to 39 years 268 1.0
40 to 49 years 343 0.7
60 years and older 138 0.3

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2026-05-13