Johnson & Johnson: COVID-19 booster is 94% effective when administered two months after first dose

Johnson & Johnson announced Tuesday that booster shots for the COVID-19 vaccine developed by the company are 94% effective.

“Our large real-world evidence and Phase 3 studies confirm that the single-shot Johnson & Johnson vaccine provides strong and long-lasting protection against COVID-19-related hospitalizations. Additionally, our Phase 3 trial data further confirm protection against COVID-19-related death,” said Mathai Mammen, M.D., Ph.D., Global Head, Janssen Research & Development, Johnson & Johnson. “Our single-shot vaccine generates strong immune responses and long-lasting immune memory. And, when a booster of the Johnson & Johnson COVID-19 vaccine is given, the strength of protection against COVID-19 further increases.”

Other findings show that the Johnson & Johnson vaccine has a stable effectiveness of 79 percent against COVID-19 related infections and 81 percent for hospitalizations. No evidence of reduced effectiveness was found for the length of the study, which was conducted from March to July of this year and included 390,000 Johnson & Johnson vaccine recipients compared to 1.52 million unvaccinated people.

For the study, booster shots were given 56 days after the initial Johnson & Johnson single-dose vaccine. Apart from 94 percent protection against symptomatic infections in the U.S., the booster was 75 percent effective against symptomatic COVID-19 globally and 100 percent protective against severe or critical infections at least 14 days post final vaccination.

“When a booster of the Johnson & Johnson COVID-19 vaccine was given two months after the first shot, antibody levels rose to four to six times higher than observed after the single shot,” Johnson & Johnson said. At six months, the booster provided a 12-fold increase in antibodies.

In areas with high Delta variant transmission, COVID-19 rates were higher. Dr. Dan Barouch, head of Beth Israel Deaconess' Center for Virology and Vaccine Research, said the vaccine’s apparent lack of effectiveness in other countries have been impacted by circulation of virus variants, according to CNN.

Early this year, the U.S. Food and Drug Administration approved the single-dose Johnson & Johnson vaccine for emergency use. Other organizations outside of the U.S. have also approved its use. A two-dose Moderna vaccine FDA approved for emergency use and a two-dose Pfizer BioNTech vaccine with full approval have effectiveness around 90 percent.