The single-shot Johnson & Johnson Covid-19 vaccine produces a strong response against the Delta variant of the virus, the company has said. A study of blood samples taken from eight inoculated people showed that the vaccine elicits neutralizing antibody activity over at least eight months against all variants, including Delta, first detected in India.

“Today’s newly announced studies reinforce the ability of the Johnson & Johnson Covid-19 vaccine to help protect the health of people globally,” said Paul Stoffels, the MD and vice chairman of the executive committee and chief scientific officer at J&J.

“This adds to the robust body of clinical data supporting our single-shot vaccine’s ability to protect against multiple variants of concern,” he added.

The company said the single-dose vaccine was 85 per cent effective against severe or critical disease and demonstrated protection against hospitalization and death. The shot neutralized the delta variant within 29 days of a first dose, and protection matured and improved over time.

It also said that the efficacy was consistent across all regions studied globally, including in South Africa and Brazil. There was a high prevalence of rapidly emerging Beta and Zeta variants during the study period.

“We’re delighted, actually, and confident there’s no need for the booster at the moment, and we are protected against different strains,” Johan Van Hoof, J&J’s global head of infectious diseases and vaccines, was quoted as saying by Bloomberg.