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One study was conducted by the South African Medical Research Council and involved more than 69,000 healthcare workers from mid-November to mid-December.
According to a statement from Johnson & Johnson, two Johnson & Johnson shots reduced the risk of hospitalization from the variant by up to 85% during the trial.
When a booster shot was administered six to nine months after a primary single dose, vaccine effectiveness increased over time from 63% at 0-13 days, to 84% at 14-27 days and 85% at one to two months post-boost, according to the statement.
“Data from the (South Africa) study confirm that the Johnson & Johnson COVID-19 booster shot provides 85% effectiveness against hospitalization in areas where Omicron is dominant. This adds to our growing body of evidence which shows that the effectiveness of the Johnson & Johnson COVID-19 vaccine remains strong and stable over time, including against circulating variants such as Omicron and Delta,” said Mathai Mammen, M.D., Ph.D., Global Head, Janssen Research & Development, LLC, Johnson & Johnson, in the release. “We believe that the protection could be due to the robust T-cell responses induced by the Johnson & Johnson COVID-19 vaccine. Furthermore, these data suggest that Omicron is not affecting the T-cell responses generated by our vaccine.”
In a second study, conducted by Beth Israel Deaconess Medical Center, research indicated using the Johnson & Johnson shot as a booster for those who received two initial doses of the Pfizer vaccine generated a 41-fold increase in neutralizing antibody responses.
Using the Pfizer shot as a booster, however, generated a 17-fold increase in neutralizing antibodies, according to the release.
That study involved an analysis of the blood of 65 vaccinated people.
“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, M.D., Ph.D., Director of the Center for Virology and Vaccine Research at BIDMC, in the release. “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.”