The Surgeon General of Florida, Dr. Joseph Lapado, announced this week that the state would specifically recommend against Covid-19 vaccinations for healthy children, making it the first US state with such a policy.
Asked about the science, Lapado, dodged. Had he come prepared, he could have mentioned data indicating that the pediatric vaccines provided less protection against infection during Omicron than during earlier waves. That would have been cynical, as I'll discuss below. But some people, anti-vaxxers in particular, simply would not have cared.
Florida is making the wrong move.
In fact, the more we learn about Covid-19 vaccines for kids and adolescents, the clearer it is that the vaccines work and are essential for ending the emergency phase of the pandemic. The key question is, what is the right dosing regimen for each age group? That remains unclear.
Here’s where we are up until now.
Adolescents ages 12 and up are authorized for the full 2-dose adult regimen and are eligible for boosters 5 months after the initial series. Prior to Omicron, we had good evidence that the 2-dose series decreased infection for some time and was associated with excellent protection against severe disease for far longer in this age group. I’m aware of no data suggesting that boosters improved outcomes among those infected, beyond the stellar protection provided by 2 doses. Boosters for this age group may delay infection, and for some that’s a good enough reason to boost. But as of now, it is not inherently dangerous for adolescents to stop after 2 doses. (It is dangerous for people over age 50 and others with severe immune compromise to stop after 2 doses.)
Children ages 5-11 are authorized to receive a 2-dose series of a 10-microgram formulation (1/3rd of the 30-microgram adult dose). Prior to Omicron, we had good evidence that the Covid-19 vaccines decreased infection, and there was reasonable data to infer protection against severe disease.
Currently, children 6-months to 5-years of age remain ineligible for vaccination. Pfizer tested a 2-dose 3-microgram series (1/10th the adult dose) last year. The trial initially showed promising results for children up to 2-years of age, but disappointing results for children ages 2- to under 5-years. This led Pfizer to study whether a 3rd dose adds efficacy, which is ongoing. (In mid-February, Pfizer reversed its plan to ask the US Food and Drug Administration to proceed with an emergency use authorization that would have permitted administering two doses to all children under 5 while awaiting data on whether 3rd doses would successfully “top it off.”)
When Pfizer unexpectedly abandoned its application for all children under age 5, including the 6-month to 2-year-olds, in whom the 2-dose low-concentration formulation had apparently worked in the trial, many wondered why. Had Omicron negated the positive findings in the youngest kids? And many also wondered whether this implied that the vaccines authorized for children ages 5 and older no longer worked.
A new study with impressive data from New York state provides insights on all of this. Researchers assessed pediatric vaccine performance during the Omicron period (note: the study has not yet undergone peer review). The headlines were not welcome ones. The overall message was that for children ages 5-11, 2-doses of the 10-microgram injection no longer provided very much protection against infection during the Omicron wave, although the regimen continued to provide some protection against severe disease. The findings match another recent paper published by the Centers for Disease Control and Prevention, which straddled the Delta and Omicron eras.
After reading the New York study, my takeaways were similar, though I see the data as more positive than the headlines suggested. In both the 5-11- and 12-17-year-old groups, the 2-dose series still appears effective enough that every child should receive it, even in the face of Omicron. For adolescents ages 12-17, vaccine effectiveness for infection dropped from 85% in late November to 51% by the end of January. But the protection against hospitalization was sturdier, dropping from 100% pre-Omicron to 80% after December 13th, 2021.
Some readers may have noticed that other media outlets reported less rosy vaccine effectiveness numbers on hospitalization (i.e. a drop from 94% to 73%) than those I just mentioned. The higher figures I reported reflect how well the vaccine performed in preventing hospitalizations that were deemed to have been primarily due to Covid-19. These figures excluded children who were hospitalized with either an incidental infection (e.g. admitted for a broken leg and found to have coronavirus) or with Covid-19 as a secondary cause of the admission (e.g. a hospitalization for an asthma emergency that a coronavirus infection likely contributed to).
I believe there is a very strong argument to use the higher numbers (which I found in the “appendix” of the New York study) that reflect only the vaccine's effectiveness in preventing hospitalizations primarily caused by Covid-19. How could a Covid-19 vaccine possibly decreased the odds of a kid breaking that leg? In reality, among hospitalizations for purely orthopedic injuries, the rate of incidental coronavirus infection detected at the time of admission just reflects the prevalence of Covid-19 in the community. If 5% of the community has an active case, around 5% of orthopedic hospitalizations would be expected to test positive for the virus, just by chance (Note: it still remains useful information for hospitals to detect these cases, so that they can take the proper isolation precautions).
A similar analysis of the data for children ages 5-11 yields the same conclusion. For preventing hospitalizations primarily caused by Covid-19, the vaccine effectiveness fell from 100% during the first week of Omicron, coming in at 65% effective for the 7-week Omicron period included in the study (in contrast to vaccine effectiveness against hospitalization of only 48% when incidental Covid-19 hospitalizations were included in the analysis).
Where does this leave us? For the moment, despite the concerning headlines, and the appalling scientific illiteracy of Florida's so-called "experts," very little has changed. The vaccines still work in the children for whom they are authorized. The CDC still recommends vaccinating all children ages 5 and older, and I agree with that.
That said, Omicron clearly decreased the effect of the vaccines, in particular for short-term protection against infection. And this may provide a key insight on why Pfizer pulled back on its plan to start vaccinating children under age 5 with two doses of the 3-microgram formulation while awaiting information on whether the 3rd dose would finish the job. If the protection was already somewhat low in children under age 5 in the initial weeks after vaccination (when protection would be highest) in a study that was conducted during the Delta era, it’s likely that Omicron wiped that signal all away. Studying a 3rd dose makes sense (though I wish they were also simultaneously studying a higher dose so that if the 3rd dose fails, we have something else to fall back on). Moderna is also expected to have results for a trial of its vaccine in this age group soon. Answers are coming.
Final thoughts: You may have noticed that above I wrote that nothing has changed with respect to the importance of vaccinating all children over the age of 5 against Covid-19. And yet, I did not provide the explicit side-by-side risk-benefit analysis that Inside Medicine readers may have (I hope) come to expect. So I’ll return to this important topic in a few days to discuss another wrinkle found within this new data from New York and elsewhere. In that piece, I’ll reassess the overall risk-benefit of pediatric Covid-19 vaccines, and I’ll show you why the overall picture, including the latest data we have, only strengthens the case for vaccinating children.
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