By Nikhila Natarajan

New York, Jan 29 (IANS): America is on the cusp of vaccine number three with Johnson & Johnson's long-awaited single shot vaccine candidate which has shown 66 per cent effectiveness against Covid-19.

This number is less than Pfizer's and Moderna's effectiveness but still better than what President Joe Biden's chief medical adviser Dr. Anthony Fauci was willing to embrace with open arms months before the first vaccines came online.

"These topline results with a single-shot Covid-19 vaccine candidate represent a promising moment. The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunisation, is a critical component of the global public health response," said Paul Stoffels, Chief Scientific Officer, Johnson & Johnson.

America needs multiple vaccines to succeed to shut the door on the pandemic. The two that are currently in use are both two shot vaccines and the Biden administration's Covid-19 team has been pinning its hopes on adding a third to the mix. The new government has promised to deliver 100 million shots in arms over its first 100 days in office.

J&J said Friday that in the US and seven other countries, its single-shot vaccine was 66 per cent effective overall at preventing moderate to severe illness, and 85 per cent protective against the most serious symptoms.

The results have shown geographic variation, working better in the US - 72 per cent compared with more muted results in South Africa, where a mutated virus is spreading rapidly.

The company expects to file an emergency use application in the US within a week. It expects to supply 100 million doses to the US by June and a billion doses globally by the end of 2021.

The study results published today are based on interim findings from a pool of 44,000 volunteers. Researchers tracked illnesses starting 28 days after vaccination - about the time when, if participants were getting a two-dose variety instead, they would have needed the second shot. After day 28, no one who got vaccinated with J&J's candidate shot needed hospitalisation or died regardless of whether they were exposed to the original virus or the mutation.