COVID-19 vaccine effective in adolescents

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.

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