Johnson & Johnson’s vaccine for the coronavirus disease 2019 (Covid-19) has been found to activate some immune responses against several coronavirus variants, according to a study published Wednesday by Harvard researchers.

The results of the large Phase 3 study, published in the journal Nature, showed the activity of immune responses among 20 vaccinated individuals against Covid-19 and four variants.

According to the research, the one-shot vaccine led patients to produce virus-neutralizing antibodies and T cells, which are often considered the soldiers of the immune system.

Volunteers in Brazil and South Africa, where coronavirus variants have widely circulated, were found to produce five-times fewer neutralizing antibodies than those faced with the original Covid-19 strain, but they made roughly as many antibodies of other kinds, including T cells, and were well protected against the variants.

The analysis says the vaccine protected against severe and critical Covid-19 in 86 percent of recipients in the United States, 88 percent in Brazil and 82 percent in South Africa.

“These findings have implications for vaccine protection against SARS-CoV-2 variants of concern,” the study concluded.

Researchers who developed the vaccine, which is produced by Johnson & Johnson subsidiary Janssen, noted that the study shows it protects populations worldwide against severe Covid-19, regardless of variant.

“This is good news in terms of coverage of the variants, and it increases our optimism that the current vaccines, particularly this one, has good coverage of the variants that exist today,” said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston.

The lead researcher said the findings serve as a good reason why everyone “should get vaccinated as soon as possible.” He also said researchers are still investigating why the vaccine might produce some blood clotting disorders in some recipients.