Dr. Matthew Muller

We sat down with Dr. Matthew Muller, infectious diseases physician at St. Michael’s Hospital, to talk about how to protect yourself this viral season. Check out the full interview here.

What is the difference between RSV, COVID-19 and the flu?

A lot of people are wondering what the difference is between all of the respiratory viruses we’re hearing about such as COVID-19, RSV and influenza. These are all respiratory viruses which means that they can cause an upper respiratory tract infection where you might have symptoms like a runny nose or sore throat, but they can also cause more severe infections, particularly pneumonia. And so they’re lumped together as respiratory viruses.

But obviously, there are differences with respect to the three viruses. I think the most notable difference is that influenza and RSV have been around for a long time. We’ve known a lot about them. Whereas with COVID-19, the virus that causes it recently caused a large pandemic and we’re still recovering from that. As a result, immunity to COVID-19 is different from immunity to flu and RSV and we don’t have as defined a season for COVID-19.

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We see waves or times when there’s high COVID-19 activity and low activity, but there’s always COVID-19 out there. On the other hand, influenza is much more of a virus that comes in the fall and winter and is largely gone in the summer except in rare instances. The symptoms of these three viruses really overlap and it’s not always possible in mild cases to distinguish between them.

What can we expect this viral season?

As we know, we always have a seasonal influenza outbreak or epidemic in the fall and winter and I would expect that to be no different than in previous years. We also tend to have RSV incidents increase at some point over those same months, so we’re going to see both of those viruses circulating widely in the community and in hospitalized patients over that time period. With COVID-19, the epidemiology has been changing over time. Based on what we saw last year, we also expect that as we get into the cooler months the amount of COVID that’s in the community will be quite high.

We have seen that in Ontario the levels are already high but they’re going to continue to rise as we move into the winter months, and then sometime in the New Year I expect they’ll start drifting down and they’ll reach their lowest point again next summer, although it may not go away completely. So what that means is that we’re likely to have multiple significant respiratory viruses circulating, which can put people at risk of getting sick, and it is also a threat to vulnerable patients and vulnerable populations.

Who is most at risk?

A lot of people want to know if they’re at risk for these viruses and particularly if they’re at risk for severe disease or being hospitalized because of an infection with RSV, influenza or COVID-19. The risk factors for these three viruses are also similar, but not identical. We know with COVID-19 that the single biggest risk factor is age and the older you are, the higher your risk of severe infection.

But there are many other factors that can increase your risk. Many different medical conditions that people may have, such as cancer, kidney disease, liver disease or lung diseases, such as obstructive lung disease, all can increase your risk of getting severe COVID-19. And for all three viruses, there’s particular concerns about, getting them in pregnancy. For RSV, this is a disease that in most adults is fairly mild. In the very young, especially infants, there’s a significant risk of getting more severe disease and it’s one of the most common reasons for hospitalization.

In the elderly, RSV can cause severe disease that results in hospitalization. It can effect immunocompromised populations. Flu is quite similar to those things.

What vaccines are available?

For the COVID 19 vaccine, this vaccine is recommended for all Canadians six months and older. And I would strongly encourage everyone to get this particular vaccine. It will reduce your risk of getting COVID-19 over the winter season and will also reduce your risk of getting severe COVID-19. It’s important to recognize with COVID-19 that your immunity, whether it’s from prior vaccinations or previously having COVID-19 or both, does decrease over time. Unless you’ve recently had a confirmed episode of COVID-19, I would strongly encourage everyone to get that vaccination. Similarly, the flu vaccine is available once a year and is updated to target the strains of flu that are circulating. And again, I would recommend that all adult and most kids in Ontario get their flu vaccine, as it can reduce their risk of infection and disease over the over the winter months and over the flu season.

One of the things that’s terrific about the RSV vaccine is it seems to confer long term immunity. So it’s not a vaccine that you need to get every year. So if you’ve never had it before, this is a great year to get it if you fit in one of the eligible groups. We believe it will protect you for several years into the future. You may need a booster dose at some point, but right now we’re not sure when that might happen. So you get several years of protection. This is the first season that we have really broad access to three vaccines for three important viruses and we hope that that will make a big difference as we go into what could otherwise be a little bit of a difficult fall and winter season.

How can we best protect ourselves from these viruses?

The most frequent question I’m asked is how you can protect yourself from these viruses as we go into the fall winter respiratory virus season. As I just mentioned, there is now vaccines available for all three of these viruses, and I would strongly encourage everyone to get their COVID-19 and flu vaccine and everyone that’s eligible to get their RSV vaccine. I think this is will make the single biggest difference in reducing your risk of disease and your risk of severe disease or consequences from these viruses.

But there are other things you can do to prevent the spread of these respiratory viruses. Frequent hand washing or hand hygiene has been shown to reduce the incidence of influenza, and is a terrific idea, both at home and in the workplace. Regularly washing your hands can be very helpful. Additionally masking is helpful, particularly for those of us who are most vulnerable. You may want to consider masking when you hear that there’s a lot of COVID-19, flu and RSV circulating in the community, particularly when you’re in crowded, poorly ventilated indoor spaces.

There’s really not much of a need to mask when you’re outdoors, but of course, as things get colder, we all tend to be spending more of our time in these crowded indoor spaces. This won’t protect you, but a really important consideration is whether you might infect other people. Another very important thing to do is to stay home if you feel that you do have COVID-19 or influenza to avoid infecting your colleagues or vulnerable family members that you might be visiting over the holiday season. I will emphasize that out of all of them, I think that vaccination is the most important of those strategies, but they can all work together to reduce our risk as we go through this fall and winter season together.

What is different about this year’s flu season?

Although many of us worry about the coming viral respiratory season, there are a few things to reflect on the bright side. The COVID-19 pandemic has officially been declared over, although the virus remains a very significant concern. But we can look back and say that with each wave, we’ve been more prepared, we’ve had better prevention and treatment strategies. The severity of COVID-19 has decreased over time, so this is a positive thing. A real miracle of the pandemic was the rapid development of a COVID-19 vaccine that can really protect us against death or severe disease from the virus. So each year, we’re in a better position to handle COVID-19 than we were the year before. And I would anticipate that although this winter season could be difficult from a health care perspective, it will be slightly less difficult than prior seasons.