While US health officials are still debating the best way to go when it comes to a COVID-19 vaccine booster, something that is clear when experts called by the Food and Drug Administration (FDA) episode met to Recent committee discussion: For stronger and longer lasting immune responses, the next booster may have to target more than one strain of SARS-CoV-2. That would make the COVID-19 vaccine similar to the annual flu vaccine, which typically helps the body build immunity against up to three different strains of flu.
On April 19, Moderna, the company that makes one of two mRNA vaccines available in the US, report The first such combination vaccine. The result is published on the print server first and has not been peer-reviewed.
In the study, nearly 900 people who received the main series of two doses of Moderna’s original vaccine were given a booster shot of the new vaccine at least six months after the initial shots. About 300 people received a booster half dose, and nearly 600 people received the full dose of the new injection. The new vaccine contains an equal amount of viral genetic material that will help the body’s immune cells make antibodies against both the original version of the virus and against Beta, one of several variants that have appeared in the past. past two years. Another 171 people served as the comparison group and received the original vaccine, with half the dose as the main series, as a booster — as currently recommended by the FDA and the Centers for Disease Control and Prevention.
In general, the combination booster induces higher antibody responses than those produced by the primary booster against not only the primary virus strain but also against other viral strains, including including Delta and Omicron, although the new vaccine does not target these virus strains and is designed to specifically target Beta. Such cross-reactivity is an encouraging sign that combining different strains can induce stronger immune responses against several different variants. In particular, for Omicron, the new booster, at half the dose of the original main series, containing genetic information from both the original virus and the Beta variant produced more than twice as many antibodies as initial booster — even up to six months after firing. The full dose produces more antibodies, but the rate of adverse reactions is also slightly higher.
Although antibodies contribute to only one type of vaccine-provided immunity, they are important for reducing the risk of contracting the virus, as well as reducing the risk of developing severe symptoms of COVID-19.
The new half-dose of the vaccine was not associated with any more adverse effects than the half-dose booster currently allowed against the original strain. However, the full dose of the new vaccine is associated with a slightly higher risk of side effects, similar to the full dose of the original booster, reinforcing the company’s previous decision to claim Authorization request for the initial booster with half of the main batch dose.
While the results of the latest study are promising, Moderna is also working on a combination enhancer that targets Omicron and the parent strain. Those results are expected later this spring. Given the popularity of Omicron and its subvariant BA.2 around the world, the company’s scientists hope that the combined Omicron intensifier could be a stronger candidate for consideration as next US booster shot in the fall, but that decision won’t be made until the results of that study are available.
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