Pharmaceutical company Moderna said its COVID-19 vaccine is 93 percent effective through six months after the second dose, but as new variants of the virus emerge, people who received the vaccine may need a booster shot before winter.

The company made the announcement as part of its second-quarter earnings release Thursday.

“We are pleased that our Covid-19 vaccine is showing durable efficacy of 93 percent through six months, but recognize that the Delta variant is a significant new threat so we must remain vigilant,” Moderna CEO Stéphane Bancel said in a statement with the earnings release. Moderna president Stephen Hoge said during an earnings call that a third booster “will likely be necessary to keep us as safe as possible through the winter season in the Northern Hemisphere.”

The company is studying what type of booster will provide the best long-term protection against the Delta variant and other possible variants of the coronavirus. Moderna said both a third shot of the original vaccine and new versions have demonstrated “robust antibody responses to COVID-19 variants of concern.”

On Wednesday, the head of the World Health Organization (WHO) asked for a moratorium on COVID-19 booster shots in higher-income countries, citing lower income countries’ lack of access to the vaccines. But White House press secretary Jen Psaki said during a press briefing Wednesday that the WHO was offering a “false choice,” noting that the US has already donated 110 million doses of the vaccine to other countries. “More needs to happen. But we believe we can do both,” Psaki added.

Moderna said it sold $5.9 billion worth of its coronavirus vaccine during the six-month period ending June 30th, for a total of 302 million doses. The company reported a net income of $2.8 billion on total revenue of $4.4 billion for the three months ending June 30th, compared to $67 million in the year-ago quarter.

https://www.theverge.com/2021/8/5/22611045/moderna-third-shot-covid-19-vaccine-booster-delta-variants-coronavirus