Johnson & Johnson has announced its one-shot coronavirus vaccine candidate is effective against COVID-19.
However, it reported lower efficacy in South Africa, where a new variant of the virus has emerged.
Overall, the firm says its vaccine is 66% effective in preventing moderate to severe illness.
The firm says its trials showed the jab was 72% in the United States, and 66% in Latin America, in terms of "preventing moderate to severe COVID-19, 28 days after vaccination".
That efficacy dropped to 57% in South Africa.
The results will, however, be welcomed, as the vaccines already approved require two doses for full vaccination.
The firm has pledged to make sure the vaccine is affordable so it can be rolled out across the world, including to poorer countries.
Johnson & Johnson CEO Alex Gorsky said: “Johnson & Johnson embarked on the global effort to combat the COVID-19 pandemic a year ago, and has brought the full force of our capabilities, as well as tremendous public-private partnerships, to enable the development of a single-shot vaccine.
“We’re proud to have reached this critical milestone and our commitment to address this global health crisis continues with urgency for everyone, everywhere.”
The firm is now set to apply to the FDA for emergency use in the US.
The announcement comes less than a day after Novavax also announced promising results for its vaccine.