Johnson & Johnson says two doses of its SARS-CoV-2 vaccine provides 94 percent protection against developing symptomatic disease in the US, according to CNN.
The company's vaccine is currently available in the US under an emergency use authorization from the Food and Drug Administration in a one-dose format. At that time, J&J said its single-dose regimen had a 66 percent efficacy overall and 85 percent efficacy in preventing severe disease.
As CNN notes, the company had been testing the two-dose regimen in a phase 2 trial in which the doses were given 56 days apart. The Wall Street Journal adds that the trial was conducted in 10 countries where it provided 75 percent protection overall against symptomatic COVID-19, though in the US the regimen provided 94 percent protection against disease.
Johnson & Johnson also announced that another study showed that a booster dose of its vaccine six months or longer after the initial dose led to a 12-fold bump in antibody levels, CNN adds. "The data are supportive of giving a second shot of the J&J vaccine, anywhere from two months onwards," Dan Barouch from Beth Israel Deaconess Medical Center who helped develop the vaccine tells the Journal. "The longer you wait, the better the boost will likely be."