Johnson & Johnson said Sept. 21 that a two-dose regimen for its COVID-19 vaccine provides 94 percent protection against symptomatic infection, which puts all three drugmakers whose COVID-19 shots are being administered in the U.S. at similar efficacy rates for two-dose regimens.
In a study in which 390,000 people received a single dose of Johnson & Johnson's COVID-19 vaccine, the drugmaker found that the single dose provided 79 percent protection against infection and 81 percent protection against hospitalization.
When participants received a booster dose 56 days after their first dose, the study found that they had 100 percent protection against severe COVID-19 at least 14 days after their second dose. It also found that the recipients had 94 percent protection against symptomatic COVID-19 in the U.S. and 75 percent protection against symptomatic COVID-19 globally.
Johnson & Johnson also found that when participants received a booster dose six months after initial vaccination, antibody levels increased ninefold one week after the booster and rose to a twelvefold increase four weeks after the booster. The drugmaker said all antibody increases "were irrespective of age."
"A single-shot COVID-19 vaccine that is easy to use, distribute and administer, and that provides strong and long-lasting protection is crucial to vaccinating the global population," Paul Stoffels, MD, Johnson & Johnson's chief scientific officer, said in a statement. "At the same time, we now have generated evidence that a booster shot further increases protection against COVID-19 and is expected to extend the duration of protection significantly."