Moderna calls for approval of two-strain Covid vaccine booster

Moderna is urging regulators to authorise its new two-strain Covid-19 vaccine booster, after releasing data that shows it increases immunity against the fast-spreading Omicron subvariants.

The US biotech group said the vaccine — which contains the genetic code for the original strain and Omicron — demonstrated a “potent neutralising antibody response” to the subvariants BA.4 and BA.5.

Stephen Hoge, Moderna president, said the higher level of protection compared with the company’s existing vaccine justified switching to the new booster, which could help prevent “a large rise in cases” in early autumn.

“We’ve been producing millions of doses over the last couple of months,” he added. “And we would hope to have tens of millions to hundreds of millions of doses available in August, September and October to support boosting prior to the fall respiratory virus season.”

However, the vaccine did not elicit as many antibodies to the new subvariants as it did to the original Omicron, suggesting its efficacy may already be declining. The new data backs up studies that have shown that previous infections from the original Omicron strain, known as BA.1, do not provide a strong antibody response against newer versions.

While global regulators prepare to discuss whether to co-ordinate a switch to the vaccines designed to target Omicron, the virus has already raced ahead. The trials of the vaccines adapted to Omicron took several months, leading some to question whether the vaccine makers should be allowed to adapt the jabs without first providing new clinical data for each tweaked version.

Uğur Şahin, BioNTech chief executive, last week called on regulators to decide by the end of June whether to approve Covid vaccines targeting the most recent virus strains without first requiring clinical data. “Time is ticking,” he told the Financial Times.

Hoge said updating vaccines to target BA.4 and BA.5 could be done more quickly without requiring a clinical trial. But he added that this was not necessary as its bivalent booster provided strong protection.

“Fortunately in this case we don’t have to make that choice,” he added. “We do have clear data showing that the updated bivalent vaccine was superior against Omicron and so we think it’s time to move forward to update our vaccine and make it available as soon as August so we can start boosting people.”

Regulators should rapidly authorise the vaccine maker to switch over production from its existing Covid jab to the new bivalent booster to facilitate the distribution of the new shots from August, the company said.

Moderna’s bivalent booster elicited a five-fold increase in antibodies to tackle BA.4 and BA.5 compared with pre-booster levels, when administered as part of a four-dose regimen. This is lower than the eight-fold increase in antibodies that the bivalent booster generated against the original Omicron BA.1 strain.

Some experts remain doubtful that Moderna’s bivalent booster will prove a game-changer that prevents future waves of infection by variants.

“Overall, it’s encouraging that the booster increases neutralising antibodies against Omicron — it would not be useful if it didn’t — but the effect of this vaccine against Omicron still seems weaker than the effect of the original booster against the Delta variant,” said David Dowdy, an epidemiologist at Johns Hopkins Bloomberg School of Public Health.