You may have seen a lot of news about the Pfizer COVID-19 vaccine for 5–11-year-old kids in the last few days.
One new report out of New York suggested that the COVID-19 vaccine for these kids does not provide much protection against getting infected. Another study from the CDC shows that the vaccines continue to provide strong protection against hospitalization and serious infection. Keep reading for a breakdown for what we know, what we don’t, and what to do from here. Sorry, friends. This is a long one.
Let’s tackle the study that is getting the most headlines first. News outlets have been reporting that the Pfizer vaccine is less effective and wanes quickly in 5–11-year-olds. Understandably, this has a lot of parents freaking out. This data is coming from a study that used three New York State databases to look at COVID-19 outcomes between November 29, 2021 to January 30, 2022. They compared outcomes for kids aged 5-17 who were vaccinated (defined as at least 14 days after their second dose of vaccine) and kids who weren’t vaccinated. They used a little bit of a funky method to calculate the vaccine effectiveness (VE). They calculated an incidence rate ratio (IRR) for new cases and hospitalization by dividing each group by the number of vaccinated and unvaccinated people each week. They use the IRR to calculate an estimated VE. This is important because this is not typically how VE is determined. More often, VE studies use what is called a “test-negative design.” In this type of study, cases are people who test positive for the disease and controls are people getting the same test for the same symptoms but test negative.
Anyway, the New York study found that the VE for infection in kids 5-11 decreased rapidly after 1 month following that second dose of vaccine (from 65% at two weeks after vaccination to 12% at 28-34 days). There was a smaller decrease in kids aged 12-17 (from 76% at 2 weeks to 56% at 28-34 days). They also found that VE dropped in the 5-11 age group from December 2021 to January 30, 2022 from 68% to 12%. Lastly, in the 5-11 age group, they found a decrease in protection against needing to be hospitalized, dropping from 100% to 48%. Meanwhile, the VE for kids ages 12-17 held up pretty well from 85% to 73%.
So, what are the take homes from this study?
➡️ This is one study, and a pre-print at that. This means it has not been peer reviewed or published in a journal. Take it with a grain or two of salt.
➡️ The design of the study is a little wonky and may lead to incorrect results. Now take it with a handful of salt.
➡️ The rates of hospitalization are low in kids, which may mean the study underestimates the VE against severe disease and hospitalization.
➡️ The amount of Omicron variant increased during the time frame of this study. The study was not designed to tell us if the vaccine effectiveness wanes or lessens over time, or if the change in VE is because Omicron is able to evade the immune system.
➡️ How often and how people test might be different between vaccinated groups and unvaccinated groups. This could impact the VE results for cases.
➡️ Even if the VEs estimated here are 100% accurate, the vaccine is still protective against hospitalization and getting really sick. That’s a big deal and vaccines are STILL ABSOLUTELY WORTH IT for kids.
Ok, so let’s move on to the next study. This one is published by the CDC in the Morbidity and Mortality Weekly Report (MMWR). You can find it here. This study looked at emergency department, urgent care, and hospitalizations for COVID-19 like illness for kids ages 5-17 across 10 states from April 2021 through January 2022. This study did use a test negative design. 😊
What did they find? For kids aged 5-11 years old, the VE against needing to go to the emergency room or urgent care was 46%. For adolescents aged 12-15 and 16-17, it was higher at 83% and 76% respectively. The VE did decrease 150 days after vaccination for those age groups, dropping to 38% and 46% respectively. However, the VE in kids 16-17 years old popped right back up after a 3rd dose (86% 7 days after the booster). Importantly, they did find that VE was decreased across the board when Omicron is the predominant variant (compared to Delta).
How about some good news? This study also supports that the vaccine remains effective to prevent hospitalizations, even in the age of Omicron. The VE against hospitalization for kids 5-11 was 74% 14-67 days after the second dose (YES!). For kids 12-15 and 16-17 up to 149 days after the second dose, the VE against hospitalization was 92% and 94%!
You might be saying to yourself. What do I do with all these numbers? What’s next? Good questions!
🤷♀️ Get comfy with ambiguity. The take home is that we need more studies to truly know how protective vaccines for kids 5-11 are and if that changes over time. It may be that these kids will need a booster shot, different timing for the vaccine series, or larger doses going forward. It’s too soon to tell.
🔧 Omicron really threw a wrench in all of this. More time and more studies are needed. Surveillance on new variants and what this means for our vaccines is critical. Vaccine manufacturers are looking at making vaccines for specific variants already.
👏 Vaccines work to protect kids against getting really sick. That’s HUGE. Vaccination in kids is super important, safe, and totally worth it.
❤ Boosters improve protection for adolescents. In the US, kids 12 and up can get a booster dose 5 months after their second shot. We expect to hear more about boosters for kids 5-11 in the next month or so.
Lots of love and lots of numbers,
Those Nerdy Girls
Even more links!
Great post from @unambiguousscience & @sciencewhizliz
MedPage Today – COVID Vaccine Less Effective in Younger Kids
