Covid-19 vaccine in adolescents

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The Pfizer-BioNTech (BNT162b2) vaccine is a safe, immunogenic and highly effective vaccine against Covid-19 in adolescents, according to findings from a new study published in the New England Journal of Medicine.

The multinational, placebo-controlled, observer-blinded trial recruited 2260 adolescents aged 12-15 years in the United States; of these, 1131 received the vaccine (BNT162b2) and 1129 were given a placebo. The two doses of the Pfizer vaccine were given at a gap of 21 days.

The vaccine had a favorable safety profile. The most common adverse effects were transient mild-to-moderate reactogenicity, mostly injection-site pain (79-86%), fatigue (60-66%) and headache (55-65%). There were no vaccine-related serious adverse events with few overall severe adverse events.

No Covid-19 cases with an onset of ≥7 days after the second dose were detected in adolescents (n=1983) who did not have previous SARS-CoV-2 infection, whereas 16 such cases were reported in the placebo group. The observed vaccine efficacy was 100% (95% CI, 75.3 to 100).

A similar vaccine efficacy (100%) was observed in all vaccine recipients (n=2229), with or without evidence of previous SARS-CoV-2 infection or not. However, there were 18 cases in the placebo group.

The observed immune response to the Pfizer vaccine in 12-to-15-year-old adolescents was noninferior to that seen in young adults aged 16-25 years. “The geometric mean ratio of the BNT162b2 neutralizing geometric mean titer in 12-to-15-year-old participants to that in 16-to-25-year-old participants 1 month after dose 2 was 1.76 (95% confidence interval [CI], 1.47 to 2.10), which met the noninferiority criterion.”

The US FDA has approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine in adolescents aged 12-15 years only last month. The CDC now recommends COVID-19 vaccination for everyone 12 years of age and older in the United States.

The Pfizer vaccine is not yet available in India. All the three vaccines available in India are approved for use in individuals older than 18 year. Trials of these vaccines in recipients younger than 18 years of age are likely to begin soon. Bharat Biotech has been accorded the green signal to conduct Phase II/III clinical trial of Covaxin in the age group 2 to 18 years.

ZyCov-D, the Zydus Cadila Covid vaccine has also been tested in more than 800 children in the age group of 12-18 years, in addition to the adult population in phase III trials. ZyCov-D is a DNA vaccine. It is the second indigenously-developed Covid vaccine and awaiting the regulators nod. Plans to test the vaccine in the 5-12 years age group are also on the agenda.

(Source: New England Journal of Medicine, May 27, 2021, DOI: 10.1056/NEJMoa2107456)