Johnson & Johnson announced that it has begun vaccinating adolescent participants in an ongoing phase 2a trial of its COVID-19 vaccine candidate Ad26.COV2.S. The study, which got under way last September, was initially designed to evaluate single- and two-dose regimens of the vaccine in healthy adults aged 18 to 55 years, as well as those 65 years and older, but is now including young people 12 to 17 years of age.
The single-dose version of Ad26.COV2.S was cleared for emergency use in people 18 and older by the FDA in February, followed by authorizations in the EU and Canada, based on results from the phase 3 ENSEMBLE trial, which showed that it had an overall efficacy rate of 66% at preventing moderate-to-severe COVID-19, four weeks after vaccination.
Johnson & Johnson indicated that in the expanded phase 2a study, its vaccine will initially be tested in a small number of adolescents aged 16 to 17 years, and that based on a review of initial data, it will be opened up to include a larger group of younger adolescents in a stepwise fashion. The trial is currently recruiting participants in Spain and the UK, while enrollment will begin shortly in the US, the Netherlands and Canada, with Brazil and Argentina to follow. According to Johnson & Johnson, the study will evaluate reactogenicity and immunogenicity of two dose levels of the vaccine, and test potential vaccination schedules at one-, two- and three-month intervals in two-dose vaccine regimens.
Studies in pregnant women, younger children planned
“The COVID-19 pandemic has had a profound impact on adolescents, not just with the complications of the disease, but with their education, mental health and wellbeing,” remarked chief scientific officer Paul Stoffels, adding “it is vital that we develop vaccines for everyone…to help combat the spread of the virus.” Mathai Mammen, Johnson & Johnson’s head of R&D, said the company is also preparing to initiate studies in pregnant women and children in the near future.
Pfizer and BioNTech reported at the end of March that in a phase 3 study of adolescents aged 12 to 15 years old, their vaccine BNT162b2 was safe and 100% effective at protecting against COVID-19. The topline results were based on an analysis of 18 cases of COVID-19, all of which were among placebo recipients. The companies also recently initiated another paediatric study of their COVID-19 vaccine in children under 12, with an initial readout expected in the second half of the year. The mRNA-based vaccine has been authorised for people 16 years and older in multiple markets, including the UK, US and EU.
Meanwhile, Moderna last year started testing its COVID-19 vaccine mRNA-1273 in children 12 years and older, and recently also began dosing those aged six months to 12 years in a Phase II/III trial, while AstraZeneca has been studying its candidate AZD1222, now also known as Vaxzevria, in children ages six years to 17 years in the UK since February.