Long-term Symptoms After SARS-CoV-2 Infection in Children and Adolescents

Discussion | In this study, initial vaccine-elicited neutralizing antibody titers were negatively associated with age, resulting in a diminished ability to neutralize SARS-CoV-2 in vitro.Neutralizing titers against P.1 were reduced across all ages, although the magnitude of the age-dependent difference was smaller.Interim clinical trial data did not identify age as a contributing factor to overall vaccine efficacy. 1However, recent studies in vaccinated populations have found a measurable increase in COVID-19 cases among vaccinated older adults. 3,4 The data from the current study are consistent with neutralizing antibody levels playing an important role in this observation.Neutralizing antibody titers are thought to be strongly correlated with protection from infection; however, the threshold of this protection has not yet been precisely determined. 5 Future studies should specifically address whether the reduced antibody levels seen among older vaccinated individuals lead to concomitantly diminished protection.Additionally, the emerging SARS-CoV-2 variants of concern, including P. 1, B.1.1.7,and B.1.351,have been widely reported to be less well neutralized by vaccine-induced antibodies and are responsible for a majority of breakthrough infections, according to a May 2021 report. 6The compounding effects of reduced neutralizing antibody titers due to both age and the variants of concern should be considered when designing policies around booster vaccinations.Limitations of this study include the small sample size and the possibility of unrecognized infection prior to vaccination.