The Dose (December 6)

Timing of Covid vaccines, common flu rumors, HPV vaccine win, and H5N1 in milk

Dec 06, 2024

Happy Friday! The respiratory season is heating up. And, if you were infected with Covid-19 this summer, a new study suggests optimal timing for a vaccine.

Here’s public health news you can use. Let’s dig in.

YLE event coming up

Paid subscribers, if you missed it yesterday, YLE is hosting our first live virtual event next Tuesday! Check out more details here.

Fall respiratory weather report: RSV and flu are heating up

We are at extremely low levels of Covid-19, but RSV is exponentially increasing, and the flu is heating up. Overall, national wastewater levels remain low, but flu and RSV will be the ones to watch first.

Kids are experiencing a lot of sickness right now—mostly from colds and walking pneumonia (10 times higher than last year). Now, we can add parvovirus B19 to the list. The number of positive tests for parvovirus is the highest it’s been in the past seven years. It’s not totally clear why the spike is happening right now, but it may be due to reduced exposure during Covid-19, which caused herd immunity to drop.

This infection is famous for causing a rash that looks like “slapped cheeks” in children and joint pain in adults. Other symptoms include fever, headache, cough, sore throat, and rashes. For those with underlying health conditions (cancer, organ transplants, blood disorders), infections can cause complications like anemia.

Insight on timing Covid-19 vaccines

It has been extremely difficult to determine the optimal timing of Covid-19 vaccines. However, new data offers some suggestions:

(Note: The following recommendations is for the Northern Hemisphere. Check out the paper for the Southern Hemisphere guidance.)

If you haven’t been recently infected, early autumn is optimal for your Covid vaccine.

The best time to get a booster is 2.7 months before the peak of a wave (assuming no recent infections). It can lead to a five-fold lower risk of infection.
In the U.S., the winter peak has consistently been the first week of January. This means an annual booster on September 15th provides the lowest yearly probability of infection.

If you’ve been recently infected with Covid-19, delaying the shot can significantly improve its effectiveness. For example, if you were infected in August, your best bet is to delay to February.

Data from Townsend et al. Supplement; Table created by YLE

Importantly, this assumes our endemic waves (one in late Summer and one in Winter) will continue. Many epidemiologists think it will, but Covid-19 could always surprise us.

It’s National Influenza Vaccination Week! There are a lot of flu vaccine rumors.

The flu vaccine prevents millions of cases, tens of thousands of hospitalizations, and thousands of deaths yearly.

There are a lot of common misconceptions about the flu vaccine. Here are a few addressed:

The flu vaccine cannot give you the flu. It has no active flu virus. (It either has fragments of the virus or an inactivated version.) Some people get the flu vaccine at the same time that flu is starting to circulate, and get an infection from the community—the vaccines are imperfect and take ~2 weeks for maximum protection.
The flu vaccines work—but it would be nice if they worked better. The flu vaccine typically is 40-60% effective in preventing illness. (This year may be a little lower, given what we know from the Southern Hemisphere’s flu season a few months ago.)
Flu vaccines are given annually since the flu virus changes quickly. Flu vaccine formulas are the best guess as to which strains will be prevalent in the upcoming season.
Severe health issues from the flu vaccine are extremely rare but real, like the risk of Guillain-Barre syndrome (GBS). Importantly, though, the risk of GBS is higher after a flu infection. One study found that people who got the flu vaccine had a rate of GBS of 6.6 per million people, whereas unvaccinated people had a rate of 9.2 per million.

An update on hospital overflow and ER boarding

You may remember back in February, YLE wrote about the escalating problem of emergency room “boarding”—where patients get stuck waiting hours to days in the ER due to overly full hospitals, leading to unsafe patient care and increased death.

At the time, we invited you to comment on a proposed clinical quality measure that the U.S. government would require of hospitals. It would set standards, collect data, and help create financial incentives to fix boarding if approved.

We have an update for you.

You guys did not disappoint: responses skyrocketed after publishing the YLE article. The measure has received an initial favorable assessment and is in another stage of vetting this month. (You can comment in support here.)

We are asking for your help again. This topic seems to be gaining momentum, as a different national organization that grades hospitals on safety and quality will potentially start including data on ER boarding in their annual hospital assessment. You can help make this happen by providing your public comment here by December 13 (select Section 6E), encouraging them to include measures of ER boarding in their annual assessment. This would be exceptional news, as it would mean more data and incentivization for hospitals to address the problem.

Change in health care is slow and often requires filling out surveys that only hospital administrators know about. But a large showing from the public is how we fix these problems.

Good news: HPV vaccinations are associated with reduced cervical cancer mortality in young women

The flood of data continues: Another study shows the effectiveness of human papillomavirus (HPV) vaccines in reducing deaths from cervical cancer. Recommended to young women since 2006 (and now recommended to all children/adolescents), HPV vaccines have reduced deaths from cervical cancer by 62% in young women! The study looked specifically at women under 25 years.

While cervical cancer mortality rates were already decreasing, it looks like the vaccine supercharged the decline. The causal argument is very strong:

There’s a consistent and strong effect across different populations,
There’s biological plausibility (HPV causes cervical cancer, and there was an intervention that we know works on a biologic level) and,
This was the first cohort of women widely advised to get vaccinated. (Note: The HPV vaccine is now recommended for children of all genders—HPV causes a number of cancers.)

Question grab bag: H5N1 in raw milk

The Santa Clara Health Department found H5N1 in raw milk on the shelves through random milk testing. After further investigation, H5N1 was also found in the producer’s (Raw Farms) storage tanks and bottling facility. (Note: RFK Jr. is linked to this company). California has asked Raw Farms to stop producing milk, and a health warning is now out. One YLE reader asked, "Why is finding H5N1 in raw milk bad? Why does public health care so much? Wouldn’t this be survival of the fittest?”

There are a lot of unknowns right now, and public health works with a precautionary lens. We don’t know if people can get infected with H5N1 from raw milk. Thus, we don’t know whether drinking raw milk increases the probability of another pandemic for everyone. (For example, are there receptors in the gut that can cause H5N1 to mutate to become more transmissible for human spread?) And, we don’t really want to find out.

However, we do know that some mammals get serious H5N1 disease from drinking raw milk containing the virus. During a livestock outbreak in Texas in early 2024, half of the cats on the ranch died after drinking milk from infected cows. In mice fed virus-containing milk in a lab, autopsies found H5N1 had spread to most of their organs within a few days.

Bottom line

You’re all caught up for the week! Have a wonderful weekend.

Love, YLE

Your Local Epidemiologist (YLE) is founded and operated by Dr. Katelyn Jetelina, MPH PhD—an epidemiologist, wife, and mom of two little girls. YLE reaches more than 280,000 people in over 132 countries and has a team of 11 whose main goal is to “translate” the ever-evolving public health science so that people will be well-equipped to make evidence-based decisions. This newsletter is free to everyone, thanks to the generous support of fellow YLE community members. To support the effort, subscribe or upgrade below: