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Any data about after-effects for the second shot in young children?

Question: Any data about after-effects for the second shot in young children? Anecdotally, none of my friends’ kids – or mine – have seemed to have any effect beyond a sore arm. 

Answer: The best data we currently have is that from the Pfizer clinical trial, which found that pain at the injection site was the most common side effect– reported slightly more frequently after the first dose (74%) as compared with the second dose (71%) (Figure 1).  Other frequently reported side effects include fatigue and headache (Figures 1 and 2).  After the first dose, 14% (vaccine group) and 9% (placebo group) took a fever reducing or pain relief medication and after the second dose, 20% (vaccine) and 8% (placebo) did.  In terms of real world data, Israel began vaccinating children ages 5-11 a few weeks ago.  On December 3rd, the Times of Israel reported that the leading HMOs in the country are not seeing any serious side effects, just sore arms and isolated cases of moderate fever.  With 6% of 5-11 year olds in the US now fully vaccinated, we should soon have analyses of real-world safety data from the US, which will hopefully alleviate any remaining concerns that parents have.  In the meantime, your anecdotal reports align with mine– my own child only experienced a sore arm after both shots and friends’ children experienced a sore arm with a few also reporting fatigue.  With that in mind, I’ll take this moment to encourage all parents to get their children ages 5+ vaccinated and to thank parents and children who already have done so.  Thank you!   

Figure 1. Local Reactions and Systemic Events Reported in the Phase 2–3 Trial within 7 Days after Injection of BNT162b2 or Placebo. (from NEJM)

Panel A shows local reactions and Panel B shows systemic events after the first and second doses in recipients of the BNT162b2 vaccine (dose 1, 1511 children; dose 2, 1501 children) and placebo (dose 1, 748 or 749 children; dose 2, 740 or 741 children). The numbers refer to the numbers of children reporting at least one “yes” or “no” response for the specified event after each dose; responses may not have been reported for every type of event. Severity scales are summarized in Table S5; fever categories are designated in the key. The numbers above the bars are the percentage of participants in each group with the specified local reaction or systemic event. 𝙸 bars represent 95% confidence intervals. One participant in the BNT162b2 group had a fever of 40.0°C after the second dose.

Figure 2. Frequency of Pfizer COVID-19 Vaccine Side Effects among Children 5-11 after 1st and 2nd Dose (data viz from Business Insider)Note: this figure shows information from Box B above, but is just a bit easier on the eyes.