UCSF

For the first comparison, we weighed predicted hospitalisations prevented by one booster dose of BNT162b2 with vaccine-associated SAEs from the manufacturer's randomised trial (3/5055).3 We found that the rate of expected SAEs would outweigh the benefits of the booster against hospitalisation by at least 18-fold. Lam and Nichols suggest that this was an inappropriate comparison, as not all SAEs result in hospitalisation. However, the definition of SAE as used in the trial included death, hospitalisation, disability, permanent damage, life-threatening event or condition, which required medical or surgical intervention to prevent a serious outcome.4 While all comparisons include some degree of incommensurability, comparing these SAEs with hospitalisations prevented by the booster is more reasonable than Lam and Nichols' suggestion of comparing SAEs to infections prevented. The COVID-19 infection hospitalisation risk in this age group was <0.5% (or <1/200)5 even prior to widespread immunity, thus comparing SAEs to infection risk is entirely inappropriate. Furthermore, a booster dose will only offer transient (if any) protection against infection6 and cumulative infection rates in the boosted versus unboosted are expected to be approximately the same after several months.6 We disagree that an SAE from vaccination should be considered equivalent to or in any way comparable with postponing an infection for a few months.