Johnson and Johnson on Tuesday said that its vaccine's two dose version provides 94% protection against symptomatic infection. It also said the booster increases antibody levels by four to six times compared with one shot alone.
Additionally, the company said, adding a booster dose to a single shot of the vaccine raised immunity even more, and should also protect people strongly against infection.
A J&J booster dose given six months out from the first shot appears to be potentially even more protective against Covid, the company said, generating antibodies twelvefold higher four weeks after the boost, regardless of age.
The company released some details of three studies looking at various aspects of its Janssen vaccine, and said that, taken together, they showed the vaccine provided long-lasting protection that could be boosted with an extra shot.
Dr. Mathai Mammen, global head of Janssen Research & Development, in a statement said, "our large real-world-evidence and Phase 3 studies confirm that the single-shot Johnson & Johnson vaccine provides strong and long-lasting protection against COVID-19-related hospitalizations,"
The new data, provided in a press release, helps J&J make a case to the Food and Drug Administration to authorize a booster shot to some 14.8 million Americans who have received the company’s single-dose vaccine.
The company's ongoing Phase 2 trial of a two-dose regimen showed giving two doses 56 days apart provided 100% protection against severe Covid-19 and 94% protection against moderate to severe Covid-19 in the United States. Globally, the two-dose regimen provided 75% protection against moderate-to-severe Covid-19, the company said.
The company also said a real-world evidence study of 390,000 people in the US, using health insurance records through July -- so covering the Delta variant -- showed the one-shot J&J vaccine was 81% effective at preventing hospitalizations.
"The Johnson & Johnson single-shot COVID-19 vaccine showed vaccine effectiveness against COVID-19-related hospitalizations at 86% for participants younger than 60 years, and 78% for those 60 years and older," the company said.
The company is in talks with regulators including the US Food and Drug Administration, the European Medicines Agency and others regarding using booster doses of its vaccine.