Update with consideration of Omicron – Interim COVID-19 infection prevention and control in the health care setting when COVID-19 is suspected or confirmed– December 23, 2021

With the identification of the new COVID-19 variant of concern-Omicron, this update has been developed to emphasize and provide additional recommendations to the COVID-19 infection prevention and control measures outlined in the COVID-19 infection prevention and control guidance documents. These recommendations are for all health care settings (acute care, long term care, home care and ambulatory/outpatient care).

Background

On November 26, 2021, WHO designated the variant B.1.1.529 (Omicron variant) a variant of concern (VOC). Subsequently, on November 28, 2021, the Canadian SARS-CoV-2 Variant Surveillance Group designated it as a Variant of Concern for Canada. Omicron is a highly divergent variant with a high number of mutations, many of these found on the spike protein. The Omicron variant has been shown to be much more transmissible than the Delta variant and has some vaccine immune escape. It is unknown if the disease severity will be different than other circulating variants.

Factors affecting the risk of acquisition of healthcare associated SARS-CoV-2 infection include:

Evidence on the transmission of SARS-CoV-2 virus has advanced rapidly and continues to emerge. Respiratory fluids continue to be the primary mode of transmission for COVID-19 via large respiratory droplets and small aerosol particles. Infections occur when respiratory mucosa (mouth, nose, eyes) are exposed to these respiratory droplets and aerosol particles. Individuals can release SARS-CoV-2 virus particles during any exhalations (e.g., talking, breathing, singing, exercising, coughing, sneezing). These aerosol particles can remain suspended in the air, and be inhaled into the respiratory tract of another person. With the arrival of the very transmissible Omicron variant, that appears to have some degree of immune escape, this new information is considered in these interim recommendations for infection prevention and control in health care settings.

Recommendations

Recommendations for health care settings include the following:

Aerosol exposure – Historically, certain procedures were thought to pose a higher risk for health care workers on the basis of case–control studies, mainly from SARS-CoV-1, that reported associations between selected procedures and health care worker infections. These have been called Aerosol Generating Medical Procedures (AGMPs). As scientific inquiry quantifies the aerosols produced by such procedures, it appears that they do not cause any more aerosols than coughing, singing or talking loudly. Aerosol production can also vary by individual. As these concepts are studied, a better understanding may lead to a change in infection control guidance. Until then it is prudent to continue to use fit tested N95 respirators, eye protection, gowns and gloves for all AGMPs.

Health care workers can choose to wear a respirator at any time taking into account such factors as the community incidence of SARS-CoV-2, patient’s ability to tolerate a mask, patient behaviours such as shouting or heavy breathing, requirement of extensive or prolonged close proximity, and other factors.

Masking for the full duration of shifts or visits

Given ongoing community spread of COVID-19 within Canada and evidence that transmission occurs from those who have few or no symptoms, masking for the full duration of shifts or visits has become normal practice during the COVID-19 pandemic. The rationale for full-shift or visit masking of all staff and visitors is to reduce the risk of transmitting COVID-19 from staff or visitors to others, at a time when no symptoms of illness are recognized, but the virus can be transmitted. The mask also protects the wearer. Depending on community transmission rates, the mask chosen can be a medical mask or a respirator. There is increasing evidence that the fit of the mask is the most important feature. Visitors should wear well-fitting medical masks or KN95 respirators (recognizing that there are many counterfeit KN95 respirators that may be difficult to verify at point of entry).

Employers must ensure that:

For all other COVID-19 infection prevention and control guidance measures please see: COVID-19 infection prevention and control guidance documents by healthcare sector.

References

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