A booster dose of Johnson & Johnson’s vaccine performed well in terms of protecting against hospitalization in people who contracted COVID-19 in South Africa, according to a study published Thursday.
A second study indicated that people who initially received Pfizer’s COVID-19 vaccine and got a Johnson & Johnson (J&J) booster saw a 41-fold increase in neutralizing antibody responses and a jump in T-cells within weeks.
The first study analyzed over 69,000 vaccinated health care workers, pegged effectiveness against hospitalization at 63 percent zero to 13 days after the boost. That figure climbed to 85 percent one to two months post-boost.
The study did not include an assessment of effectiveness past that time frame.
“We provide the first evidence of the effectiveness of a homologous Ad26.COV.2 vaccine boost given 6-9 months after the initial single vaccination series during a period of omicron variant circulation,” authors wrote in the preprint study.
They received funding from South Africa’s government and other entities, including the Bill & Melinda Gates Foundation.
In the other study, researchers with the Beth Israel Deaconess Medical Center said a J&J booster dramatically increased protection against both infection and hospitalization among those who initially got a Pfizer jab. They analyzed responses among 65 people, including 41 who got the Pfizer-J&J series.
“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,” Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at the medical center, said in a statement.
The funding sources for the second study have not been disclosed.
J&J promoted the results.
“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,” Dr. Mathai Mammen, global head of Janssen Research and Development, said in a statement. Janssen is a subsidiary of Johnson & Johnson.
J&J’s shot is one of three authorized for use in the United States, but health officials recently recommended against the vaccine unless people are unwilling or unable to get the other two vaccines.
The effectiveness of the single-shot vaccine was originally designated as 100 percent effective against hospitalization 28 days after administration, but real-world data showed that protection decreased as time went on, dropping to 65 percent over the summer. The waning effectiveness prompted regulators to authorize a booster dose.
Boosters Against Omicron
While J&J’s booster appears to perform well for at least two months against Omicron, boosters of other COVID-19 vaccines have had mixed results against the new variant of the CCP (Chinese Communist Party) virus.
Pfizer-BioNTech scientists, for instance, said earlier this month that a study found their vaccine performed 25 times worse against Omicron than the wild type CCP virus.
While a booster restored the lost protection, the study only went one month after boosters were administered.
Other studies looking at longer periods of time indicate protection from boosters began waning after several weeks.
People in the United Kingdom, officials there said recently (pdf), saw effectiveness against symptomatic disease go down to as low as 35 percent 10 weeks after a boost. Researchers in Denmark and Norway published similar results this month.
Israeli scientists, meanwhile, said in a study released Wednesday that an analysis of infections in the country indicated a “rapid waning” of Pfizer’s booster in reducing infectiousness, “possibly affecting community-level spread of the virus.”
At the same time, T-cells generated from vaccination or prior infection are holding up well against Omicron, according to two other studies.
U.S. health authorities say data so far suggests boosters provide protection against Omicron and continue to encourage people who haven’t gotten a vaccine to get one and those who have to get a booster.
With Omicron, “clearly there is a degree of immune evasion, particularly against infection and to some degree against hospitalization,” Dr. Anthony Fauci, President Joe Biden’s top medical adviser, told reporters on Wednesday.
“However, importantly, and the bottom line message here, is that boosters bring back up that degree of protection to a level that is approximating what it was before. So, boosters are critical in getting our approach to Omicron to be optimal,” he added.