Moderna announced Thursday that its two-dose mRNA COVID-19 vaccine remains effective for six months, but said on an earnings call that people will likely need booster doses before winter to combat the delta variant.
The company said ahead of Thursday's earnings call that the vaccine displayed 93% efficacy through six months after the second dose, a welcome sign as COVID cases rise nationwide, driven largely by the highly contagious delta variant.
"We are pleased that our COVID-19 vaccine is showing durable efficacy of 93% through six months, but recognize that the Delta variant is a significant new threat so we must remain vigilant,” CEO Stéphane Bancel wrote in a statement.
The company also noted in the statement that its three candidates for booster shots demonstrated "robust antibody responses" in Phase 2 studies, including against the delta variant.
"We believe a dose three of a booster will likely be necessary to keep us as safe as possible through the winter season in the Northern Hemisphere," Dr. Stephen Hoge, Moderna's president, said on the earnings call, according to the New York Times.
Moderna said that based on the "intersection" of factors including the delta variant, mask fatigue and people moving indoors due to colder weather, "we believe dose 3 booster will likely be necessary prior to the winter season."
Israel, France and Germany have authorized boosters for their most vulnerable populations, despite criticism from the World Health Organization. The head of the World Health Organization, Director-General Tedros Adhanom Ghebreyesus, called for a moratorium on booster shots Wednesday as a way to help ensure that doses are available in countries where few people have received their first shots.
"WHO is calling for a moratorium on boosters until at least the end of September to enable at least 10% of the population of every country to be vaccinated," Ghebreyesus said Wednesday.
Bancel said on Fox Business on Thursday that some countries could start seeing Moderna booster shots available "as soon as September," but they are still "waiting for a bit more data."
Moderna also said that it expects to finish its application for full Food and Drug Administration (FDA) approval this month, which many say could go a long way toward combatting vaccine hesitancy.
"Moderna has initiated the rolling submission process for a Biologics License Application (BLA) for our vaccine in the U.S. and expects to complete its submission in August," the company said in a statement.
The company began the rolling submission process in June.
"I am proud of the progress our teams at Moderna have made in the past quarter in advancing our development pipeline while addressing a global pandemic and quickly establishing global manufacturing and commercial organizations," Bancel said. "We now have mRNA candidates in clinical trials across five therapeutic areas including infectious diseases, cardiovascular, oncology, rare disease and autoimmune disorders."
The Associated Press contributed to this report.