Booster debate heating up: Moderna says booster likely needed before winter

Moderna said Thursday that its COVID-19 vaccine maintained 93 percent efficacy six months after the second dose but added that a booster shot will likely still be needed before the winter.

The efficacy rate was announced by the company ahead of an earnings call on Thursday, and is higher than the 84 percent efficacy rate of the Pfizer vaccine after the same amount of time.

Still, Moderna CEO Stephane Bancel said on CNBC Thursday that the data was collected before the delta variant became prevalent in the United States, meaning the equation could change now that the delta variant is widespread.

While there is strong data for six months, the company said in a presentation that it believes antibody levels will “continue to wane and eventually impact vaccine efficacy.”

It added that the combination of delta, fatigue with wearing masks and people moving indoors as the weather gets colder will cause an “increase of breakthrough infections in vaccinated individuals.”

“Given this intersection, we believe dose 3 booster will likely be necessary prior to the winter season,” the company said.