Two new studies of a Johnson & Johnson COVID-19 vaccine booster showed promise against the omicron variant at a time when public health officials are urgently recommending booster shots against the fast-spreading variant.

One study was conducted in some 69,000 health care workers in South Africa. Results showed the vaccine reduced hospitalizations by 85% when comparing people who got two doses of the J&J vaccine to people who had a single dose.

Unlike Pfizer and Moderna vaccines, which require two initial doses before a booster six months later, Johnson & Johnson is a single shot that can be followed by a booster dose after at least two months for people 18 and older.

The booster study was done at a time when omicron was the dominant variant in South Africa.

"This data should reassure healthcare workers who have not taken their booster to get vaccinated as soon as possible," said Dr. Nicholas Crisp, the deputy director general of the South African National Department of Health.