A booster dose Johnson & JohnsonResearchers have revealed that the single-dose Covid-19 vaccine prevented 84% of South African health workers from being hospitalized after they were infected by the Omicron variant.

The real-world study, which has not been peer-reviewed, was based on a second dose of the J&J vaccine administered to 69,092 workers between Nov. 15 and Dec. 20.

A course of initial inoculation was shown to provide only a very limited protection from infection by the omicron. This virus is rapidly spreading through many countries, having been first identified in Hong Kong and southern Africa in November.

Numerous studies suggest that the booster dose may provide significant protection from severe illnesses caused by this variant.

The South African study showed the J&J vaccine’s effectiveness at preventing hospitalization rose from 63% shortly after a booster was administered to 84% 14 days later. After a booster was administered, the vaccine’s effectiveness was 85%.

Linda-Gail Bekker was the co-lead researcher in the study. “It gives us confidence that Covid-19 vaccinations are still effective for their intended purpose, which is the protection of people against serious disease and death.”

“This is another evidence to show that even though a variant has been mutated, we still have an impact.”

Bekker said the jury was “still out” on the issue of further boosters for the J&J vaccine, which is administered as a single shot for the first full dose, and which is easier to transport to remote African rural areas than the rival, two-dose Pfizer mRNA vaccine due to better heat tolerance.

“We are proving that just two doses can restore protection. We don’t need to extrapolate that we won’t require a third or fourth.”

The researchers acknowledged that their study had limitations. They also noted that there was limited follow-up. These averaged 8 days for healthcare professionals who received their boost in the past 13 days or 32 for those who were boosted between 1-2 months ago.

In a company statement, Mathai Mammen, global head at Janssen Research & Development, said the firm believed protection could be due to robust T-cell responses induced by the vaccine.

He said that the data showed that Omicron does not affect T-cell response to our vaccine.