Moderna is launching a trial of a new Covid-19 vaccine as the US biotech group warned that its current shot was less effective in tackling the strain that emerged in South Africa.
Laboratory tests show Moderna’s Covid-19 jab still works against the variant named 501.V2, which emerged in South Africa, and B.1.1.7, which was first discovered in the UK, the company said.
But it warned that the neutralising antibody response to 501.V2 was sixfold lower than to the original variant, raising concerns that immunity to it may wane significantly, particularly in older people.
Stéphane Bancel, Moderna chief executive, said the company was preparing for a “worst-case scenario”, even though he had “zero concerns” about the vaccine’s efficacy in the coming months.
“If something needs to be done in the summer, we’ll do something, but we cannot be late,” he told the Financial Times. “We don’t want the virus to win, we want the human race to win.”
Moderna is the first vaccine maker to announce a trial for a booster against a new variant, after having its initial jab authorised across the world including in the US, the EU and the UK. Its messengerRNA technology can be quickly adapted for new variants.
The company is working with the US National Institutes of Health on the trials. Mr Bancel said a few thousand trial participants would be given a booster shot, divided into two groups: one to receive the original vaccine again, and another to get a new vaccine formulated to target 501.V2. The trial will also test to see what dose is needed for a booster.
Regulators may be able to approve a new vaccine just based on a “bridging study”, which examines participants’ antibodies to the new variant after taking a booster, rather than a lengthy phase-3 trial, which counts how many develop Covid-19 in each trial arm.
The BioNTech/Pfizer vaccine also works against B.1.1.7 but has not announced test results against the variant that emerged in South Africa.
A group of scientists in South Africa said this month that vaccines could be less effective against the 501.V2 strain, because it has an extra mutation in a key part of the spike protein that the virus uses to enter human cells.