What to expect as we head into the season for flu, COVID, and RSV

If the Thanksgiving weekend felt colder than usual, you're not wrong. Sacramento experienced its coldest November since 1985. That means even more time indoors during an already cozy holiday season. It's a combination that's ripe for flu and other respiratory viruses like RSV and COVID.

The U.S just experienced its most severe flu season in over a decade. We haven't yet entered peak flu season, but early reports from the UK and Canada are showing that a concerning strain of flu is spreading rapidly. That prompted health officials in the UK to proclaim, "It looks set to be a cruel winter with flu cases being triple what they were this time last year."

Dr. Dean Blumberg is the chief of pediatric infectious diseases at UC Davis Health. He sat down with Vicki Gonzalez to provide an update on this respiratory virus season. 

This interview has been edited for length and clarity.

Interview Highlights

What can you tell us about this latest strain of flu?

The interesting strain that we're seeing this year is one of the influenza A strains, the H3N2 subclade 7. And that one's interesting because it just really has started coming around in the world in the past few months.

So it wasn't anticipated, we didn't know it was going to be there and so that strain's not included in the current flu vaccine. It includes an H3N2 strain, but it's not that specific subclade 7 strain. And so it's less closely related, so we expect maybe less protection from the influenza vaccine this year. 

So it doesn't offer as much protection against absolute infection, but it still is expected to provide good protection against severe disease including hospitalization.

The decision on what strains of flu will be included in the vaccine are made several months ahead of time, right? 

Yeah, almost six months ahead of time, we have to decide which is the strain that we think is going to be predominant in the winter. That's based on what's circulating elsewhere in the world, choosing that strain, making sure that the manufacturers of the vaccine can grow it and purify it and that it'll be a successful vaccine in terms of inducing a good immune response.

And in the meantime, things might have changed by the time that decision is made and then the vaccine is already in the vial and distributed to pharmacies and doctor’s offices. 

There were also reports that this strain has mutated several times, so that also might complicate things as well if you're using a virus that's months old. 

Yeah, exactly. And that's one of the things that we see with influenza. It does change all the time. Sometimes it changes faster than other times and this is one of those seasons where it appears to have had a rapid change in between the time that the decisions were made on the flu vaccine and our influenza season. 

In the influenza field, the saying goes that if you've seen one influenza season, you've seen one influenza season. So, they're all just completely different. They're very hard to predict. There's so many different factors that go into it, including the different strains and the amount of immunity that's out there.

Do we have a preliminary idea of how many people so far have received their flu shot and how it compares to years past? 

The estimates are that it'd probably be less than years past. We had plateaued at about 50% of eligible people in the US being vaccinated, but in the past couple years that's dropped just a few percentage points. 

Then with all the vaccine hesitancy that we know is out there, some of it related to COVID, but some of it also driven at a national level with the calling into doubt of vaccines by the federal government, we don't expect that to change anytime soon.

A little over a week ago in mid-November, the CDC made changes to their autism and vaccines web page and the header says, "Vaccines do not cause autism,” but that now has an asterisk next to autism. And then it leads with the quote that “studies have not ruled out the possibility that infant vaccines cause autism.” 

As a doctor of pediatrics and infectious diseases, are you and your colleagues being asked more often about the safety of vaccines? How do you navigate those conversations during this time?

It's really a challenge. I think what we know that really works well in terms of confidence with vaccines is clear and consistent messaging. And so this messaging is anything but clear and anything but consistent. 

So saying something like as you've just mentioned with the change to the CDC website. It's just basically nonsensical. You could say the same thing about virtually anything.

I mean, there's no proof that cats don't cause autism. There's no proof that dogs don't cause autism or that sodas don't cause it. You can't prove a negative. So, it's sort of a nonsensical thing to say that just creates more confusion. 

We had an increase in cases when it came to COVID over the summer. Do you have an idea of what it could look like as we go into the winter?

The COVID pandemic is still evolving a bit and so what we've seen is summer surges and winter surges. Right now COVID activity is relatively low. It's starting to pick up, but it's difficult to know whether this winter is going to be a bad winter with COVID or if it's going to be as bad as the summer surge was. The past few years, the winter surge has been a little bit more than the summer surge, but not tremendously more.

Fortunately, there haven't been the development of any new, very concerning variants with COVID. And so the virus itself has not mutated that much. And, you know, that's good because that means that people have some immunity either from past infection, past immunization, or both.

With COVID, one would hope that eventually it continues in the direction it's going and as the people develop more immunity that it really becomes milder and milder. 

Remember at the beginning of the pandemic, COVID was about four times more likely to get you killed compared to getting influenza. And now they're about the same. So that's good news, that it's less severe and hopefully it continues in that direction.

This is also the season where RSV cases are on the rise. Remind us what RSV is and how it can pose a risk to certain groups, especially younger children and older adults. 

RSV is Respiratory Syncytial Virus and it’s very common. Almost every kid gets it by the time they're two years of age. And it's one of the leading causes of hospitalization among young children.

Children under two years of age often get bronchitis, constricting of the medium-sized vessels in their lungs and this causes difficulty breathing and often results in a short hospital stay. So, one to two percent of children in the past would end up in the hospital due to RSV.

Now, that's changed because we do have RSV vaccines for the extremes of age both for those under one year of age and for those 65 years of age and older and other specific groups. And the vaccines are working very well. The childhood vaccine results in about an 80% reduction in hospitalization and the adult vaccines are also protecting very well, about 70% reduction.

A person can get sick with more than one of these respiratory viruses at the same time, correct?

Yeah, co-infections may occur and getting a viral infection also may predispose you to getting a bacterial infection. So having influenza or COVID or RSV can predispose you to getting bacterial pneumonia or sinusitis because the mucus membranes get thickened and might trap bacteria in certain areas. 

For those who get vaccinated but they still fall sick and might not feel as confident about the effectiveness of these vaccines, what would you like them to know? 

Well, if you get sick even after getting vaccinated with the flu vaccine and you don't end up in the hospital, maybe it's the flu vaccine that you should thank for that. 

And if you do end up in the hospital, but not in the ICU, maybe you should still thank the flu vaccine for it not being as severe.

And if you end up in the ICU, but not dead, maybe you should still thank the flu vaccine for protecting against that more severe outcome.

Unfortunately, it won't protect everybody. But being vaccinated, we know that's the number one thing that you can do to protect yourself  against the worst outcomes from influenza. 

When is the best time to get the flu shot? 

Right now is a really good time to get the flu shot. It takes about two weeks to build up that immunity. If you haven't been vaccinated, now would be a really good time to get vaccinated, before there's even more influenza circulating. 

And does the same go for the COVID vaccine or if you qualify for the RSV vaccine? 

Yeah, for the COVID vaccine, it takes about 10 to 14 days to develop the immunity and similar with the RSV vaccine for adults.