The National Institutes of Health (NIH) has initiated a Phase I/II clinical trial to evaluate the safety and immunogenicity of mixed Covid-19 vaccine regimens.
As part of the trial, adult volunteers who have been completely vaccinated against Covid-19 will be given booster doses of different vaccines.
The study is funded and led by the NIH unit of the National Institute of Allergy and Infectious Diseases (NIAID) through the Infectious Diseases Clinical Research Consortium.
NIAID director Anthony Fauci said: “Although the vaccines currently authorised by the US Food and Drug Administration offer strong protection against Covid-19, we need to prepare for the possibility of needing booster shots to counter waning immunity and to keep pace with an evolving virus.
“The results of this trial are intended to inform public health policy decisions on the potential use of mixed vaccine schedules should booster doses be indicated.”
Individuals who are yet to receive an FDA authorised Covid-19 vaccine can also enrol in the trial in a separate cohort.
These volunteers will initially receive the two-dose Moderna Covid-19 vaccine regimen. Roughly 12 to 20 weeks later, they will be assigned to receive a booster dose of a vaccine.
Led by principal investigators Robert Atmar at Baylor College of Medicine and Kirsten Lyke at the University of Maryland, the trial includes approximately 150 individuals who already have received one of the three Covid-19 vaccine regimens.
The three vaccines Janssen’s Ad26.COV2-S, Moderna’s mRNA-1273, and Pfizer-BioNTech’s BNT162b2 are currently available under FDA emergency use authorization (EUA) in the US.
About 25 people aged 18 to 55 and approximately 25 people aged 56 and above will be part of each vaccine group.
With an adaptive design, the trial is expected to add arms as vaccines secure EUA and/or variant lineage vaccines become available for evaluation.
One year after receiving their last vaccination, all trial participants will be followed as part of the study. Initial trial results are expected this year.