U.S. scientists are expanding efforts to evaluate when fully vaccinated people will need booster shots — and, if so, whether people can switch brands — in the latest chapter of the global quest to stop the pandemic.
John Beigel, associate director for clinical research in the Division of Microbiology and Infectious Diseases at the National Institute of Allergy and Infectious Diseases, is working on a U.S. trial, set to launch this week, that will provide one piece of the answer, testing whether people can mix and match shots when the need arises. Can a person fully vaccinated with Pfizer-BioNTech’s vaccine in February take a third shot of Moderna? Is there an advantage — or a risk — in switching from one brand or vaccine technology to another?
One possibility is that those people would get sick, but another is that even if protection wanes, the immune system “is going to recognize the virus quickly upon infection and still protect,” said John R. Mascola, director of NIAID’s Vaccine Research Center.
Companies have already been testing boosters, including an additional shot of their own vaccines and revamped boosters designed against the variant. A test of the Moderna boosters showed that a third shot and a variant-specific version both increased antibody levels — an encouraging sign. A study of yet another booster option that would offer protection against the original strain and the variant-specific virus is ongoing.
The mix-and-match trial should help answer practical questions about how to best use vaccines, and will consider public health questions — such as whether there are advantages or risks to switching brands or technologies. The trial is designed to yield results by midsummer, in hopes it could inform decisions as soon as this fall if necessary, Beigel said.
The trial will test which combinations work best, and may simply show that any vaccine can be used — which could ease logistics so that people were not bound to one brand or technology platform.