Older population: COVID hospitalizations still dominate. Infants and young children: RSV leads.

Meanwhile, Flu and Covid are battling for supremacy in the middle

Early in the Covid-19 pandemic, mitigation measures successfully “flattened the curve,” bought time until vaccines became available, and also wiped out just about every other respiratory virus.

No matter the age group, the leading cause of serious viral illnesses in the United States was the same: Covid.

Over time, with mitigation measures having disappeared from most settings, the usual seasonal viruses made their return.

Data snapshot.

In this week’s Data Snapshot, we can clearly see which of the three major viruses the CDC tracks is driving hospitalizations in different age groups this season.

Data: CDC. Image: Benjy Renton and Jeremy Faust.

For anyone over age 50, Covid-19 is associated with far more hospitalizations than flu or RSV. In fact, as you look into the older age groups, Covid-19 hospitalizations still tower over RSV and flu. After age 65, Covid-19 appears to be hospitalizing more people than RSV and flu combined. It’s not even close in the oldest groups.

At the other extreme, RSV has a commanding lead over flu and Covid-19 among infants and children of daycare and preschool age.

In school-aged kids (ages 5-17 years), flu leads. For adults ages 18-49, flu and Covid are similar, but Covid has the edge, especially as you get into the older part of that group.

It’s important to realize that the burden of these hospitalizations are not all the same. While RSV can be extremely dangerous—even deadly—for infants, a large majority of these hospitalizations are for respiratory observation. That’s not the usual case for flu and Covid-19 hospitalizations, especially as you get further from infancy.

Vaccines and antibodies could help.

The CDC recommends that everyone get a seasonal flu and Covid-19 vaccine. There are also recommendations for RSV vaccinations during pregnancy and in older, high-risk individuals. For infants and certain high-risk infants, there are anti-RSV antibodies.

I think readers of Inside Medicine might hear about how low vaccine rates are in the general population and throw their arms up in despair.

Hey, I hear you.

But when I look at these graphs, something a little different stands out to me. To my eyes, these graphs contain compelling data that targeted efforts to shore up vaccinations in key groups might be a better use of public money than the current one-size-fits all strategy. Since this season officially began (October), well over 70% of Covid-19-related hospitalizations have occurred in a group comprised of infants (under 1 year old) and seniors ages 65 and up. This population represents something like 18% of the population. The number of vaccines you have to administer to decrease a single hospitalization in seniors is probably around 40-times lower than for adults ages 18-49. Let’s approximate and say that we might have to vaccinate 10 octogenarians to save a single hospitalization (a reasonable estimate); Meanwhile, you’d have to vaccinate 400 adults ages 18-49 to prevent a single hospitalization in that age group.

Assuming the CDC’s sampling data reflect nationwide rates, nearly 1% (1 in 104) of all people older than 85 in the US have been hospitalized with Covid-19 in the last 4 months alone. That’s a lot! Meanwhile 1 in 4,166 adults ages 18-49 have. Those are real and important outcomes that we should try to avoid. But if we are trying to keep hospitals from overflowing, it’s clear where our efforts should be focused.

If we wanted better outcomes at the population level, the CDC’s vaccination recommendations wouldn’t have to change. (There are reasonable quibbles on a few things, but that is not the point here.) What I’d love to see is a massive investment in getting vaccines and antibody immunizations to the most at-risk people, especially those in underserved communities. Let’s go door-to-door to reach those who we (“public health”) often have trouble reaching.

So, sure, we’d all like to cheer for higher seasonal vaccine rates across the board. It’d be wonderful to get seasonal vaccine rates from, say, 25% to 50% or higher in some younger groups. That would feel good and look nice on paper—and it would indeed decrease some bad illnesses among rare younger individuals who are hit unusually hard, either due to known risks or by chance.

But I’ll tell you what would impress me more: if we used our public health funding and infrastructure to get vaccination rates among the highest-risk and underserved populations up by just 1%-5% next year. That would lead to tens of thousands of fewer serious illnesses (and maybe hundreds of thousands, if we did it right). If we did just this—sought out the highest-risk and most underserved people in our communities and made sure they had access to these amazing vaccines and immunizations—our hospitals would be a lot less busy at the peak of the respiratory virus season.

That would make hospitals safer for everyone.

Comments? Questions? Chime in!

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Thanks to Benjy Renton for maintaining the Inside Medicine Covid-19 Metrics Dashboard and for helping with the snapshot.