Moderna Covid booster produces strong antibody response against Omicron

Moderna’s Covid-19 booster shot elicits a strong antibody response against the Omicron variant of coronavirus, appearing to increase antibody levels even further than a third dose of the Pfizer vaccine.

The Boston-based biotech said its half-dose booster increased antibody levels 37-fold, compared with people who received just two doses. BioNTech and Pfizer have previously said their booster lifts antibody levels 25-fold, though the studies may not be directly comparable.

But Stéphane Bancel, Moderna’s chief executive, on Monday said Moderna would also continue to invest in developing a vaccine targeted to the Omicron variant, in case it became necessary in the future, putting it into clinical trials early next year.

“The dramatic increase in Covid-19 cases from the Omicron variant is concerning to all. However, these data showing that the currently authorised Moderna Covid-19 booster can boost neutralising antibody levels 37-fold higher than pre-boost levels are reassuring,” he said.

A full dose of Moderna’s vaccine boosted antibody levels even further, by 83-fold. The company also announced safety data for the full dose booster, saying side effects were at similar levels to the previous two doses but slightly more frequent than for the half-dose.

BioNTech and Pfizer have previously announced that a third dose of their Covid vaccine boosts antibody levels by about 25-fold, although the data may not be directly comparable. The pair are also preparing a shot targeted to Omicron, which it has said will be available by March.

Moderna’s half-dose booster contains more messengerRNA — the genetic code that allows the body to create the spike protein and generate an immune response — than Pfizer’s full dose.

Working with scientists from the US National Institutes of Health, Moderna tested how antibodies from vaccine recipients taken 29 days after boosting reacted to a pseudovirus, engineered to include the mutations seen in the Omicron variant. The data will be published in a preprint paper.

The study’s results back up a finding by the Ragon Institute in Boston last week, which showed a steeper drop-off in antibody levels for Pfizer’s shot than for Moderna’s, but when boosted, both vaccines did well at tackling Omicron.

The lab also found that mRNA vaccines were better at boosting antibody responses than the Johnson & Johnson shot, which uses an adenovirus platform similar to that used by Oxford/AstraZeneca.

Shares in Moderna rose 6.5 per cent to $314.07 in pre-market trading in New York on the announcement.