Giving a full dose of Moderna's Covid-19 vaccine as a booster shot provides more antibody protection against the Omicron variant than currently authorised half-strength injections, the company said Monday.
The lab study measured the levels of Omicron-neutralising antibodies in blood samples from 40 people who had low levels of these antibodies before getting the booster.
The current recommendation is to give 100 micrograms of the Moderna jab as a first and second dose for protection from Covid-19, followed by a 50-microgram booster.
Antibodies were measured 29 days after booster participants got the third jabs, with half getting a 50 microgram dose and half getting 100 micrograms.
Moderna says preliminary data show antibody response to Omicron at the 50 microgram dose increased 37-fold -- but when the dose was doubled, antibody levels increased 83-fold.
Moderna CEO Stephane Bancel called the results "reassuring", adding that the company is continuing to develop an Omicron-specific jab.
The statement says clinical trials for a targeted vaccine are likely to begin in early 2022.
Experts urge caution when interpreting lab studies, saying real-world evidence is needed to determine protection against transmission and illness.
Last week a real-world study from South Africa showed two shots of the similar mRNA jab from Pfizer/BioNTech offered around 70 percent protection against severe disease caused by Omicron.
In an interview published Monday in French daily Le Monde, BioNTech CEO Ugur Sahin said that after a third injection the jab seemed to provide between 70 and 75 percent protection against any form of the illness.
He added that his company should be able to offer an Omicron-specific vaccine from March, pending approval from regulators.