Johnson & Johnson Says COVID Booster Dose Increases Virus Antibodies

A booster of Johnson & Johnson's (J&J) one-shot coronavirus vaccine offers a stronger immune response months after people receive their first dose, the company said Tuesday.

In a statement, J&J said an extra dose either two months or six months after the initial shot increased defense against the virus. The results, however, have not yet been peer reviewed or published, the Associated Press reported.

The J&J vaccine, considered an important weapon against COVID-19 for its one-shot protection, started running a global test to see whether two doses could improve its effectiveness as the U.S. began distributing vaccines to the public.

Dr. Paul Stoffels, J&J's chief scientific officer, said in a statement that "a booster shot further increases protection against COVID-19 and is expected to extend the duration of protection significantly."

For more reporting from the Associated Press, see below.

J&J Vaccine
A booster of Johnson & Johnson's (J&J) one-shot coronavirus vaccine offers a stronger immune response months after people receive their first dose, the company said Tuesday. Above, a member of the Philadelphia Fire Department prepares a dose of the vaccine at a vaccination site in Philadelphia on March 26, 2021. Matt Rourke/AP Photo

That two-dose approach was 75 percent effective globally at preventing moderate to severe COVID-19, and 95 percent effective in the U.S. alone, the company reported—a difference likely due to which variants were circulating in different countries during the monthslong study.

Examined a different way, the company said when people got a second J&J shot two months after the first, levels of virus-fighting antibodies rose four to six times higher. But giving a booster dose six months after the first J&J shot yielded a 12-fold increase.

The company previously published data showing its one-shot dose provided protection for up to eight months after immunization. It also pointed to recent real-world data showing 79 percent protection against coronavirus infection and 81 percent protection against COVID-19 hospitalization in the U.S. even as the extra-contagious delta variant began spreading.

J&J said it has provided the data to regulators including the U.S. Food and Drug Administration, the European Medicines Agency and others to inform decisions about boosters.

J&J's one-dose vaccine is approved for use in the U.S. and across Europe, and there are plans for at least 200 million doses to be shared with the U.N.-backed COVAX effort aimed at distributing vaccines to poor countries. But the company has been plagued by production problems and millions of doses made at a troubled factory in Baltimore had to be thrown out.

As the Delta variant spread worldwide, numerous governments have considered the use of booster shots for many of the COVID-19 vaccine options.

Last week, advisers to the FDA recommended people 65 and older get a third dose of the COVID-19 vaccine made by Pfizer and German partner BioNTech. A final decision is pending.

Britain previously authorized booster shots for people 50 and over and to priority groups like health workers and those with other health conditions. Countries including Israel, France and Germany have also begun offering third vaccine doses to some people.

The World Health Organization has urged rich countries to stop giving booster doses until at least the end of the year, saying vaccines should immediately be redirected to Africa, where fewer than 4 percent of the population is fully vaccinated.

Last week in the journal Lancet, top scientists from the WHO and FDA argued that the average person doesn't need a booster shot and that the authorized vaccines to date provide strong protection against severe COVID-19, hospitalization and death.