The study, which has not yet been peer reviewed, looked at hospital admissions from mid-November to mid-December, as the country experienced a wave of omicron infections, and compared the boosted health-care workers with people who had not been vaccinated. It found that the booster was about 85 percent effective in preventing hospital admissions from covid-19, one to two months after the second dose.
In a statement shared Thursday, Johnson & Johnson said that the preliminary findings demonstrated the booster’s effectiveness in the face of a highly transmissible omicron variant of the virus, which is now dominant in South Africa.
Nicholas Crisp, deputy director general of the South African National Department of Health, said in the statement that he hoped the data would “reassure healthcare workers who have not taken their booster to get vaccinated as soon as possible.”
The research authors noted that their analysis had limitations, including short follow-up times in the study.
According to Johnson & Johnson, a second study conducted at the Beth Israel Deaconess Medical Center in Boston highlighted that the booster’s success may be due to its ability to prevent severe infection by evoking a strong immune response from cells known as T-cells.
“As the Omicron variant has mutated from the original SARS-CoV-2 strain, there is a need to understand how effective currently authorized COVID-19 vaccines remain at protecting against severe disease,” said Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel.
“Our analysis shows that a booster shot of the Johnson & Johnson COVID-19 vaccine generated a robust increase in both neutralizing antibodies and T-cells to Omicron,” he added.
The single-dose Johnson & Johnson vaccine has been in use in the United States since early 2021, and in October the Food and Drug Administration authorized its booster shot. However, this month the director of the Centers for Disease Control and Prevention recommended Pfizer-BioNTech or Moderna shots over Johnson & Johnson, citing concerns over the increased risk of a potentially fatal blood clot issue.
The new findings come as countries across the world move to contain the spread of the contagious variant, imposing stringent lockdowns, reintroducing restrictions and canceling public New Year’s Eve events.
From across Europe to the United States, governments around the world are continuing to urge people to get vaccinated or go for their booster shots.
Calls for boosters and for the unvaccinated to change their minds have been further amplified by the omicron outbreak. The pandemic has claimed almost 823,000 lives in the United States, according to Johns Hopkins University data.