TL;DR: Recent real-world data from the US show that COVID-19 vaccines for kids ages 6 months to 5 years reduced their risk of visiting an ER with COVID-19 by half or more for at least 60 days after their last dose.
Protection started to decline after 60 days, similar to what we have seen in older age groups.
Researchers reviewed the medical records of tens of thousands of kids ages 6 months to 5 years who visited an emergency room with symptoms of COVID-19 between July 2022 and June 2023.
COVID-19 symptoms can also be caused by a number of other conditions such as influenza, RSV, asthma, etc., so many times, these visits are not caused by COVID-19. The analysis focuses on one measure: what percent of these children tested positive for COVID-19.
Comparing this percentage between vaccinated and unvaccinated kids can tell us if unvaccinated kids are relatively more likely to come to the ER with COVID-19.
The researchers report a lot of different comparisons. For example, let’s look at the results for kids who had two doses of the monovalent Moderna vaccine, with the last dose at least 60 days before the ER visit. 2.7% of these kids tested positive for COVID-19. 97.3% had some other cause of their symptoms. Meanwhile, 5.3% of the unvaccinated kids tested positive for COVID-19. Comparing the two percentages shows that the odds of testing positive for COVID-19 are higher for unvaccinated kids. In fact, it’s about twice as high. This ratio is called vaccine effectiveness (VE). In this study, the researchers got a little fancier and adjusted for age, gender, and a number of other factors–so their effectiveness estimates aren’t quite a simple ratio, but this is the basic idea.
There is a similar story across the two vaccine brands available for this youngest age group and all the different dosing combinations: Vaccinations against COVID-19 reduced the odds of going to the ER with COVID-19 by at least half for at least 60 days after the last dose. After that, protection started to decline. These results are similar to what we’ve seen in other age groups.
It’s worth noting that the study period here was after the big spring 2022 Omicron surge, so we can assume that most of these children had already had COVID-19 at least once before these data were collected. That means vaccination reduced the risk of little kids visiting the ER, even with previous infections in the mix.
The bottom line: kids in the youngest eligible age group whose parents decided to vaccinate them against COVID-19 were less likely to go to the ER with COVID-19 between July 2022 and June 2023.