Why this year's flu season is hitting harder

A preliminary report from the Centers for Disease Control has found that this has been one of the worst recorded flu seasons the country — and state — has experienced in more than a decade.

Data from the California Department of Public Health found that roughly 1 in 5 Californians were still testing positive for the week ending Feb. 22. Other respiratory illnesses like COVID-19 and RSV are currently not as prevalent with a 2% and 5% test positivity rate for the same week. 

Sacramento wastewater data showed that Influenza A levels peaked at the start of February and dropped consistently until Feb. 23, when it began to rise again. 

Dr. Dean Blumberg, chief of infectious pediatric diseases at UC Davis Health, spoke with Insight Host Vicki Gonzalez to learn more about why this flu season is so bad, and what it means for children and younger people. 

This conversation has been edited for length and clarity.

Interview highlights

This flu season has been called one of the deadliest in years. Why is this happening?

What we're seeing are two flu strains that are predominantly being circulated now. Both of them are Influenza A. One is H1N1 — that has a pretty good match with the vaccine. But the H3N2 is not a very good match, so we're seeing a lot of breakthrough cases. Fortunately, it appears that cases are peaking or may have peaked last week. Historically flu cases usually peak around this time, sometime between December and February, and then they linger. Later on in the season, we do expect to see an uptick in Influenza B cases. 

If someone has not gotten their flu shot yet, would it be worth it to get one now?

Yes, since there are three strains that typically circulate every year. Even if you've had influenza, or even if you've dodged Influenza A, it's still worthwhile to be protected against what we expect to be with Influenza B coming on. It's always good to be vaccinated.

What do current vaccination rates look like for this season? 

Yeah, I don't have any information on this season’s vaccination rates. We'll probably get that later in the year in July or August. But typically the rates have remained stagnant over the past several years. About 50% of kids and adults every year have been vaccinated and we really haven't been able to move the needle on that.

There are antiviral drugs of course like Tamiflu. Are those effective? 

If you give them early enough in the illness, you can decrease the severity of illness, you can decrease risk of hospitalization, and you get better faster. Even though it might not seem like that much, if you get better faster a day or two earlier by taking antivirals, that could be significant in your life. It’s just no fun being miserable with all the raging symptoms of influenza, including the body aches and high fevers.

Other respiratory viruses like RSV and COVID-19 are also circulating. Could someone catch more than one virus at once?

Yeah, co-infections do occur with these viruses. If you do get a co-infection, it's worse than getting just one at a time. It's obviously better to have no infections, but if you do have one, it's better than having two or three at a time. 

Given that you're also the chair of pediatric infectious diseases. How is it affecting children and younger people?

We're certainly seeing cases in children. Some cases unfortunately have had to be admitted to the hospital. In the U.S. as a whole, there've been almost 100 pediatric deaths so far this year. So it's been a really bad year for influenza for children. Of those pediatric deaths, typically half of those children have been previously healthy with no underlying conditions. So it's not just dangerous for those who are immunocompromised or who have risk factors, for any kid it can be serious.

When it comes to RSV and COVID-19 at the same time during flu season, what are those cases looking like compared to flu?

This has been the mildest COVID winter season that we've had since the pandemic started. Presumably that's because we haven't seen any new threatening variants. In addition, now we have a really good level of population immunity. So when people do get COVID, it's less likely to be severe. RSV also peaked relatively early this year and appears to be on the downswing, so fortunately, we're not dealing with multiple viruses peaking at the same time.

When it comes to the messaging around getting vaccinated, do you think it’s sticking? Is it effective?

I think with influenza there generally has been more simplified messaging. But unfortunately, since there are breakthrough illnesses with influenza, some people just don't believe in the vaccine. Now, those breakthrough illnesses are milder than would occur if somebody wasn't vaccinated, so there's still a benefit to being vaccinated even if you get influenza. It's going to be a shorter duration of illness. You're less likely to have complications. With COVID, I think the messaging on vaccines has been pretty complicated with the multiple doses per year. Nobody wants that. I think we're moving towards a yearly dose of COVID vaccine for most people in the fall, when we do expect COVID to turn into a more seasonal disease.