“Current data for the eight months studied so far shows that the single-shot Johnson & Johnson Covid-19 vaccine generates a strong neutralising antibody response that does not wane; rather, we observe an improvement over time,” Mathai Mammen, head of research & development at J&J's drugs business, said in the statement.
Recipients of the vaccine produced strong neutralising antibodies against all variants including the Delta, the US-based company said.
The Delta variant contributed to a surge in Covid-19 cases in India that resulted in the highest daily death tally in the world, and also prompted the UK to delay its reopening by one month in June.
J&J has submitted data as a preprint to the website bioRxiv ahead of peer review.
Other vaccine makers including Pfizer-BioNTech, Moderna Inc, and AstraZeneca Plc have previously said that their Covid-19 vaccines are effective against the fast-spreading Delta.