COVID-19 Vaccine Efficacy in Adolescents Shown Through Real-World Data

Messenger RNA (mRNA) COVID-19 vaccines are effective in protecting adolescents against COVID-19, according to a recent study.

As of June 30, 2022, 83.4% of European adults and 76.8% of US adults had received vaccinations against COVID-19. Use of mRNA vaccines was extended to adolescents so that herd immunity could be reached.

As evidence on the effectiveness of mRNA vaccines in a real-world environment is lacking, investigators conducted a retrospective cohort study on the efficacy of mRNA vaccines against COVID-19 in an adolescent population. The study occurred from July 15, 2021, to December 31, 2021, and analyzed Sicilian adolescents aged 12 to 8 years.

Participants who had received 2 mRNA COVID-19 doses were compared with unvaccinated individuals. Diagnosis of COVID-19 was evaluated, determined by a nasopharyngeal swab test. Clinical information on patients who tested positive for COVID-19 was collected if available.

There were 274,782 participants in the study. For both the vaccinated and unvaccinated groups, cases of positive COVID-19 diagnosis, mild COVID-19, severe COVID-19, intubation, and death were recorded.

Groups were divided further based on positive COVID-19 diagnosis. The 4 subgroups were: vaccinated without COVID-19, vaccinated with COVID-19, unvaccinated without COVID-19, and unvaccinated with COVID-19.

About 61% of participants received mRNA vaccination during the study period. COVID-19 infection, mild COVID-19, and severe COVID-19 were all more frequent in unvaccinated individuals. In all follow-up models, vaccination proved to be significantly effective against all forms of COVID-19.

Vaccine effectiveness (VE) was 71.2% against infection, 92.1% against mild COVID-19, and 97.9% against severe COVID-19. These are similar results to those discussed in a recent report analyzing real-world data.

Older adolescents were more likely to develop COVID-19, which investigators predicted was because of social behavior patterns. In general, infections were observed 100 days after vaccination. This indicated a decline in VE over time.

These findings confirmed effectiveness of mRNA vaccines against COVID-19 in adolescents, reinforcing the important of vaccination among this age group.

This article originally appeared on Contemporary Pediatrics.

Reference

Amodio E, Genovese D, Mazzeo L, Martino L, Restivo V, Vella G, et al. Effectiveness of mRNA COVID-19 vaccines in adolescents over 6 months. Pediatrics. 2022;150(5):e2022057394. doi:10.1542/peds.2022-057394