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August 25, 2021

Booster shots enhance COVID-19 immunity in Johnson & Johnson vaccine recipients, data shows

The company said it will work with U.S. officials to develop a potential strategy for administering second doses

A booster shot of Johnson & Johnson's COVID-19 vaccine generates a "rapid and robust" increase in the recipient's antibody response against the coronavirus, according to new data released Wednesday by the company.

Previous data, published last month in the New England Journal of Medicine, confirmed that the single-shot vaccine generated a strong immune response at least eight months after immunization. 

But the antibodies generated by a booster shot were nine times higher than they were 28 days after the initial dose, the new research shows. Even when a lower-dosed booster shot was given, there was still a significant antibody response. 

The data comes from two clinical trials submitted Tuesday to the preprint site medRxiv. The studies have not yet been peer-reviewed, and Phase 3 trials are still needed to confirm safety and efficacy.   

Last week, federal health officials said people who received the Pfizer-BioNTech and Moderna vaccines will need booster shots eight months after their second doses. They said people who received the Johnson & Johnson shot likely will need a booster too, but more data is needed before a plan can be put into place. 

The call for boosters comes as COVID-19 cases are surging due to some combination of the more contagious delta variant, relaxed restrictions and potential waning immunity among vaccines.

Only about 14 million U.S. residents have received the Johnson & Johnson vaccine, according to data from the U.S Center for Disease Control and Prevention. That represents about 8% of the people who are considered fully vaccinated. 

A booster dose of the Johnson & Johnson vaccine "further increases antibody responses," said Dr. Mathai Mammen, global head of Janssen Research & Development at Johnson & Johnson.

"We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson COVID-19 vaccine, boosting eight months or longer after the primary single-dose vaccination," he said.

Johnson & Johnson also is studying a two-dose vaccine in an ongoing Phase 3 trial that will enroll as many as 30,000 people.

The Johnson & Johnson vaccine is different from the mRNA vaccines developed by Pfizer-BioNTech and Moderna. It uses a genetically-modified adenovirus that mimics the coronavirus's spike protein to produce an immune response. Non-modified adenoviruses cause the common cold.

Common side effects include pain, redness of the skin, and swelling at the injection site as well as headache, fatigue, nausea and fever. In rare situations, blood clots have also been reported within two weeks of vaccination.

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