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According to the first results published on Wednesday, the reinforcement of the Modern SARS-CoV-2 vaccine developed specifically with variant B.1.351 takes into account the efficacy against this strain and variant P1 among people already vaccinated against COVID-19.
In addition, data from the company’s ongoing phase 2 study show that variant-specific reinforcement, known as mRNA-1273.351, achieved higher antibody titers against variant B.1.351 than a reinforcement with the original Modern vaccine.
“We are encouraged by these new data, which reinforce our confidence that our reinforcement strategy should be protective against these newly detected variants. The strong and rapid rise in titers to levels above primary vaccination also clearly demonstrates the ability of l ‘MRNA-1273 to induce memory immunities,’ ‘Stéphane Bancel, CEO of Moderna, said in a statement.
Researchers in the Phase 2 study are also evaluating a multivariate booster that is a 50/50 blend of mRNA-1273535 and mRNA-1273, the initial vaccine with FDA emergency use authorization, in a single vial.
Unlike the two-dose regimen with the original vaccine, boosters are administered as a single-dose vaccine.
Trial participants received reinforcement 6 to 8 months after primary vaccination. Wild-type SARS-CoV-2 virus titers remained high and detectable in 37 of 40 participants. However, prior to reinforcement, headlines against the two variants of concern, B.1.351 and P.1, were lower, with approximately half of the participants showing undetectable levels.
In contrast, 2 weeks after receiving a booster with the original vaccine or strain-specific product B.1.351, pseudovirus-neutralizing titers were increased in all participants and all variants were tested.
“Following [the] increase, the geometric mean titers against wild-type variants, B.1.351 and P.1 increased to levels similar to or higher than the maximum titers previously reported against the ancestral strain (D614G) after primary vaccination, ”the company.
Both booster doses of mRNA-1273,351 and mRNA-1273 were generally well tolerated, the company reported. Safety and tolerability were generally comparable to those reported after the second dose of the original vaccine. Most adverse events were mild to moderate, with pain at the injection site more common in both groups. Participants also reported fatigue, headache, myalgia and arthralgia.
The company plans to publish data shortly on the effectiveness of reinforcement at additional time points beyond two weeks for mRNA-1273535, a lower dose booster with mRNA-1272/351, as well as data on its reinforcement of the multivariate mRNA vaccine.
In addition to the company’s Phase 2 study, the National Institute of Allergy and Infectious Diseases is conducting a separate Phase 1 study of mRNA-1273535.
Damian McNamara is a staff Miami-based journalist. It covers a wide range of medical specialties, including infectious diseases, gastroenterology and neurology. Follow Damian on Twitter: @MedReporter.