TL;DR: Moderna’s kids vaccine hit high marks for safety and antibody response, but efficacy against mild illness was not as high as earlier trials (likely due to Omicron).
Moderna announced yesterday (via press release) that they will submit for Emergency Use Authorization (EUA) of their vaccine for kids aged 6 months to < 6 years.
As a reminder, the kids vaccine trials have generally been much smaller (6700 participants here in compared to 30,000+ in the adult trial). The primary emphasis is on testing for safety/side effects and comparing antibody response with the doses known to be effective in the other trials via “immunobridging.”
Given the high levels of Omicron infection during the trial, they researchers could also directly estimate efficacy against symptomatic infection, which typically requires a larger sample (when the infection is more rare).
Moderna’s pediatric vaccine uses 2 doses of 25 µg, compared to 100 µg for their adult dose (and 50 µg for the Moderna booster).
➡️ Immune response (measured by neutralizing antibodies) was similar to the response in adults aged 18-25 receiving two full doses. This was the primary endpoint, suggesting the lower dose in kids elicits a similar immune response to that known to be effective at older ages.
➡️ The estimated efficacy against symptomatic illness was 44% for 6mo-2-year-olds and 38% for 2 to 5-year-olds. Thankfully there was no severe COVID disease reported in either the vaccine or placebo group.
Since this trial was run while Omicron was dominant, it’s not surprising that the efficacy against mild disease was lower than previous trials—we’ve seen this reduction in vaccine efficacy against Omicron for all ages.
Given the similar boost in immune response from the vaccine compared to older groups, it’s reasonable to assume the vaccine lowers the (already low but not zero) risk of severe disease in kids.
➡️ Side effects: 15-17% of kids had a mild fever after the vaccine, which was similar to other commonly used pediatric vaccines.
➡️ NO cases of myocarditis were reported, and no new safety concerns. This is good news, as Pfizer’s trial for younger children also saw no myocarditis but uses a lower dose.
⬇️ BOTTOM LINE:
The news looks good for Moderna’s kids vaccine being reviewed and potentially available soon (they estimate early summer).
While the efficacy against symptomatic disease is not as high as those early trials, Omicron has changed the game for that. In our view the news is still good because:
1️⃣ Lowering the chance of symptomatic illness in a child by 40-50% is still great. And if not infected, a child can’t spread the virus.
2️⃣ Moderna is also testing a booster dose which will likely greatly improve this efficacy against variants as it does in older ages.
3️⃣ Protection against severe disease is likely much higher -and the risk we most want to guard against in kids.
In addition to submitting this latest data to the FDA, Moderna has initiated an application for authorization of its vaccine for children aged 6 to 11. They are also updating their EUA submission for children 12 to 17 years old, which has been pending since last year due to initial concerns about myocarditis.
Several countries, including Canada, have already authorized Moderna’s vaccine for teens and children as young as 6.
🙏 We know the parents of the little ones are waiting so patiently for the opportunity to give some protection to their kids. It’s still slow going, but this is indeed progress and one step closer.
Love,
Those Nerdy Girls
Links:
“Moderna to ask FDA to authorize Covid-19 vaccine in children 6 months to 6 years”
Great coverage of this news from our colleagues:
Unbiased Science Podcast – Click here for link
Science Whiz Liz & Unambiguous Science – Click here for link
Why vaccinate kids? Read this great explainer from Voices for Vaccines and Dr. Paul Offit.
