Moderna Inc.’s coronavirus vaccine remained more than 90 per cent effective after six months, according to a new analysis of data from the company’s final-stage trial.

Beginning two weeks after the second dose, the shot was more than 90 per cent effective overall, and more than 95 per cent effective at preventing severe cases, according to a statement. The company didn’t release further details and said the follow-up results were preliminary as the study is continuing.

The results are similar to those seen after six months with the messenger RNA vaccine from partners Pfizer Inc. and BioNTech SE. In early April, those companies said their vaccine remained 91.3 per cent effective through as long as six months, according to long-term follow-up data from their final-stage trial.

Combined, the companies’ announced findings suggest that protection induced by both messenger RNA vaccines remains strong for at least a number of months. The shots use genetic material to temporarily turn the body’s cells into tiny vaccine-making factories.

Animal Studies

Moderna also said that data from mouse studies showed that several variant-specific vaccines and booster shots it’s testing produced higher levels of antibodies against variants in lab animals. The company said it would release the animal data in a preprint and plans to submit it for publication in a scientific journal.

The findings “give us confidence that we can proactively address emerging variants,” Chief Executive Officer Stephane Bancel said in the statement. “Moderna will make as many updates to our COVID-19 vaccine as necessary until the pandemic is under control.”

Fast-spreading variants have led to an uptick in COVID-19 cases in parts of the U.S., especially the Midwest, with Michigan charting the highest rate of new infections in the country.

Moderna also said that as of April 12, it had delivered 132 million doses of vaccine, including 117 million to the U.S.

In the initial results from Moderna’s final-stage trial, its vaccine was 94.1 per cent effective at preventing symptomatic cases of COVID-19. That was based on a median follow-up of 63 days after the second dose, according to the results published in the New England Journal of Medicine. Its trial of more than 30,000 people has now accrued more than 900 COVID-19 confirmed cases overall, including over 100 severe cases, the company said.