Johnson & Johnson vaccine. (Ronni Newton / photo)

Johnson & Johnson said Tuesday that people who receive a booster shot of its COVID-19 vaccine two months after the first dose had better protection against severe illness. 

For people in the trial who received the booster two months after getting the first, the protection increased to 94 percent in the U.S. and 75 percent globally. 

A booster shot at six months provided a 12-fold increase in antibodies and when it was administered six months after the single shot, antibody levels increased nine-fold and continued to climb to 12-fold four weeks after the booster.

“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,” Dr. Mathai Mammen, global head of Janssen Research & Development, Johnson & Johnson, said in a press release. “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.”

The study included 390,000 people who received the Johnson & Johnson COVID-19 vaccine versus approximately 1.52 million unvaccinated people matched on age, sex, time, three-digit zip code, and comorbidities and predictors for COVID-19 infection severity conducted from March to late July 2021.

The company says it submitted the data to the U.S. Food and Drug Administration. 

In April 2021 the Advisory Committee on Immunization Practices recommended a temporary pause to distribution of the Johnson & Johnson vaccine following blood clots in women under the age of 50. It has since recommended that it can resume. 

It means that fewer people received the Johnson & Johnson vaccine than those who have received the Pfizer and Moderna vaccines. 

An estimated 14.6 million Americans have been given the Johnson & Johnson vaccine, compared to 67.7 million with the Moderna vaccine and 99.3 million with the Pfizer-BioNTech vaccine, according to the CDC. 

“It is critical to prioritize protecting as many people as possible against hospitalization and death given the continued spread of COVID-19 and rapidly emerging variants. A single-shot COVID-19 vaccine that is easy to use, distribute and administer that provides strong and long-lasting protection is crucial to vaccinating the global population,” Paul Stoffels, J&J’s chief scientific officer, said in a statement. “At the same time, we now have generated evidence that a booster shot further increases protection against COVID-19 and is expected to extend the duration of protection significantly.”