Allison McGeer MD, FRCSC

bh IN BRIEF

Dr. Allison McGeer is the Director of Infection Control at Mount Sinai Hospital in Toronto and Professor in the Dalla Lana School of Public Health at the University of Toronto. Dr. McGeer’s research team is currently undertaking research studying the risk factors and features of COVID-19 with a grant from the Canadian Institutes of Health Research.

Many people are wondering – What will happen when the influenza season gets underway? How will it impact the health care system? And, will getting the flu shot make a difference? Dr. Allison McGeer, an expert in microbiology at Mount Sinai Hospital in Toronto provides evidenced-based information about what to expect this flu season.

What is the impact of the upcoming flu season given that we are in the middle of the COVID-19 pandemic?

There are several potential interactions between flu season and the pandemic that are of concern. The biggest concern is that a surge of either infection can temporarily stress the healthcare system, and that the combination of a regular flu season and a surge in COVID-19 cases could easily result in a shortage of ventilators, intensive care unit beds, and perhaps hospital beds overall. This scenario would mean cancelling surgery (further increasing backlogs), and potentially reducing quality of care for all hospitalized patients.

The second issue is that it is difficult to run vaccination programs given that many are avoiding in-person contact, particularly for the most vulnerable. If this hesitation causes vaccination rates to be lower than expected this year, that will further increase the burden of the upcoming flu season.

Do you expect rates of seasonal flu and/or the severity of the illness to be different this year because of COVID-19? Is there a risk of contracting both viruses at the same time?

We are all hoping that the combination of travel restrictions and reduced contact between people will reduce transmission of influenza and make the incidence of influenza low this year. This is what appears to be happening in Australia and New Zealand.  However, Australia and New Zealand are islands and have much more stringent controls on travel than Canada. Since the approach here in Canada is to keep restrictions on contact as minimal as possible, we are still uncertain about what influenza season will look like this winter.

The potential impact of a dual infection is a concern. The risk for any one individual is low, but a non-trivial risk at the population level, and the combination of the two viruses might produce very severe infections.

Considering the probabilities of contracting influenza and COVID-19, and the population size of Canada, about 190 dual infections would be expected per week. This is a non-trivial number. In addition, we know that outbreaks of both influenza and COVID-19 are concentrated in long-term care homes, and both have severe outcomes in this very frail population.

What impact will getting the flu vaccine have on the ability to manage the COVID-19 pandemic?

The more people who get the flu vaccine, the less influenza there will be circulating in the community. If more people get vaccinated there will be fewer hospitalizations due to flu and its complications, which takes the pressure off our hospitals and saves lives. It means fewer COVID-19 and influenza infections, and fewer respiratory outbreaks, particularly in long-term care homes.

Since influenza infection has similar symptoms to COVID-19, a test is needed to rule out COVID-19. This could mean being off work or out of school while waiting for test results, and household contacts may be in the same position.

For all of these reasons, it is a really good year to get vaccinated.

Who should get the flu vaccine this year? Who is most at risk and when is the best time to get the shot?

Canada’s National Advisory Committee on Immunization recommends that every Canadian over the age of 6 months who doesn’t have contraindications to the vaccine should receive their influenza vaccine each year.

The only contraindications to vaccination are a previous allergic reaction to a component of the vaccine or a diagnosis of Guillain Barre syndrome within 6 weeks of a previous influenza vaccination.

Is there any risk to getting the flu vaccine?

The more relevant question is actually whether getting a flu shot is more or less risky than not getting a flu shot.  While getting the flu shot has risks, not getting a flu shot leaves you susceptible to influenza infection, which has greater risks. bh