Winter flu season outlook

A look ahead to winter respiratory virus season

I don’t know about your household, but last winter was brutal for my family. I have young kids in school, and they were constantly hit with various bugs throughout the so-called “tripledemic.” I’m already starting to wonder: will this year be more of the same?

I did a pretty good job of calling last season. I suspected we would see an early-than-usual flu season in July, and

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and I warned in September that childhood illnesses would flare. I thought I’d push my luck by trying a long-term forecast again this year.

This is guesswork, so think of it as you would a Farmer’s Almanac outlook.

Punchline

I anticipate this will be a high-normal winter respiratory virus season. It won’t be quite as bad as last year, but still higher than what we normally saw in pre-pandemic times.

Deep dive

I can’t think of a reason why COVID-19 would depart from its habit of surging in the winter months, so that’s my expectation again this year. We’ve been circulating through Omicron variants for over a year now, and they seem to have staying power, so we’ll likely get more of the same. (On the other hand, if a brand new variant does become dominant, we would be in for a larger wave.)

Many of the young children who are vulnerable to RSV will have gotten it last year, so I expect that the population-level susceptibility is lower now than it was last year. Still, even severe winter respiratory virus seasons don’t infection everyone, and new babies have been born since the last wave, so I expect the conditions for a worse-than-average year are present again. There was also a sizable wave of RSV in Australia, which is further evidence that it will be another significant RSV season in North America.

Older adults are also vulnerable to severe RSV, but I have less of a sense of the disease dynamics in that population. Luckily, there will be an RSV vaccine available to help protect people 60 years of age and older soon. It’s expected to become available this fall.

Australia’s 2023 RSV season was less severe than 2022, but still quite active. Source.

Influenza season is in full swing in Australia, so we can get a preliminary sense of how things are unfolding there.

Last flu season, Australia (and later the Northern Hemisphere) saw activity begin very early. They did not see that pattern this season, which suggests we can expect a more typical winter start here in the North. Peak week and duration are not unknown, but I think we can rule out a year of unusually low activity.

On the bright side, H1N1 is the most prevalent influenza strain again this year. It’s what dominated last year, and it’s included in the vaccine again this year. South Africa and parts of Southeast Asia are seeing some H3N2, which is also in this year’s vaccine. The seasonal influenza vaccine is generally available by September, and it’s a good idea to get it before Thanksgiving.

Australia’s 2023 flu season hints at what the Northern Hemisphere can expect. Source.

Lastly, I’m thinking that the other pesky respiratory viruses like the seasonal coronaviruses will behave similar to what I’m expecting for RSV, which is to say it may be another big season. There was a large buildup of the susceptible population in the years where people were wearing masks and social distancing. There is no way that one bad year reset things totally, so I think there will be plenty of activity again this year.

What it all means

For my family, I’m prepared for another year of stuffy noses and sick days. I just hope it’s not as extensive as the 2022-2023 season.

For healthcare systems that creaked under the load of respiratory virus season even before the pandemic, I do suspect that it may be another tough winter. I hope some of the thinking I’m sharing, imperfect though it may be, can help to shape early preparations.

How are you using this information? Let me know in the comments.