Moderna says booster shots rev up immune response to coronavirus variants

A booster shot of Moderna’s coronavirus vaccine revs up the immune response against two worrying coronavirus variants, the company reported Wednesday.

And a booster dose formulated specifically to match the B.1.351 variant first seen in South Africa was even more effective, Moderna said in a statement.

Vaccine makers are trying to get out ahead of the new variants and the design of the new mRNA vaccines made by Moderna and Pfizer make this easier than it would have been in the past. The genetic material used as the basis of the vaccines is made in a lab and the sequence is easily tweaked.

Moderna tested booster doses of either its current vaccine or a version designed specifically against B.1.351 in 40 people who had already been vaccinated six to eight months before. Blood tests showed half these volunteers had a low antibody response against B.1.351 and the P.1 variant first seen in Brazil before they got the booster shot.

Two weeks after the booster, their antibody levels had grown against the so-called wild type coronavirus — the variant most common around the world — as well as B.1.351 and P.1, Moderna said in the statement.

It’s good news, as these two variants have mutations that allow them to partly evade the natural immune response as well as the immune response elicited by vaccines.

“The majority of adverse events were mild or moderate in severity,” the company said.

“We are encouraged by these new data, which reinforce our confidence that our booster strategy should be protective against these newly detected variants. The strong and rapid boost in titers to levels above primary vaccination also clearly demonstrates the ability of mRNA-1273 to induce immune memory,” Moderna CEO Stéphane Bancel said in the statement.

The company is also testing a vaccine booster that combines the original formulation with the B.1.351 specific formula. The boosters are half-doses, delivering half as much active ingredient as the initial doses in the two-dose regimen.

“We will continue to make as many updates to our COVID-19 vaccine as necessary to control the pandemic,” Bancel said.

The company has submitted the data, collected as part of a Phase 2 trial, to a pre-print site and said it would submit for publication in a peer-reviewed journal when it gets more data from the trial.