Johnson & Johnson said on Thursday that a real-world study showed its single shot COVID-19 vaccine protects against breakthrough infections and hospitalisations for up to six months.

The study, sponsored by the vaccine developer, was conducted between January 1 and September 7 last year, before the Omicron variant was discovered.

It is also yet to be peer-reviewed.

J&J said protection against infection from its single dose vaccine starts to wane only from the fourth month compared to the second month in the case of two-dose vaccines from rivals Pfizer Inc and BioNTech’s as well as Moderna.

No waning of protection was found for ICU admissions for all the three vaccines, J&J said.

The company said the study was carried out by collecting claims and laboratory data covering 168 million people.