The US Food and Drug Administration’s scientists confirm that overall the vaccine has 66 percent efficacy in preventing moderate illness from the virus.

Vials labelled
Vials labelled "Covid-19 Coronavirus Vaccine" and sryinge are seen in front of Johnson&Johnson logo in this illustration taken February 9, 2021. (Reuters)

Johnson & Johnson’s single-dose vaccine offers strong protection against severe Covid-19, according to an analysis by US regulators that sets the stage for a final decision on a new and easier-to-use shot to help tame the pandemic.

The Food and Drug Administration’s scientists confirmed that overall the vaccine is about 66 percent effective at preventing moderate to severe Covid-19, and about 85 percent effective against the most serious illness. 

The agency also said J&J's shot — one that could help speed vaccinations by requiring just one dose instead of two — is safe to use.

That’s just one step in the FDA’s evaluation of a third vaccine option for the US. On Friday, the agency’s independent advisers will debate if the evidence is strong enough to recommend the long-anticipated shot. Armed with that advice, FDA is expected to make a final decision within days.

READ MORE: Austria bets on millions of tests to contain Covid-19

The vaccination drive has been slower than hoped, hampered by logistical issues and weather delays even as the country mourns more than 500,000 virus-related deaths. 

So far, about 44.5 million Americans have received at least one dose of vaccine made by Pfizer or Moderna, and nearly 20 million of them have received the second dose required for full protection.

J&J tested its single-dose option in 44,000 adults in the US, Latin America and South Africa. Different mutated versions of the virus are circulating in different countries, and the FDA analysis cautioned that it's not clear how well the vaccine works against each variant. 

But J&J previously announced the vaccine worked better in the US – 72 percent effective against moderate to severe Covid-19, compared with 66 percent in Latin America and 57 percent in South Africa.

Still, South Africa recently began giving the J&J vaccine to frontline health workers on a test basis after deciding that a vaccine from rival AstraZeneca hadn't shown strong enough study results.

Across all countries, Wednesday's analysis showed protection began to emerge about 14 days after vaccination. But by 28 days after vaccination, there were no hospitalisations or deaths in the vaccinated group compared with 16 hospitalisations and 7 deaths in study recipients who received a dummy shot.

READ MORE: What is behind Chile's successful vaccination program?

The FDA said effectiveness and safety were consistent across racial groups, including Black and Latino participants.

Like other Covid-19 vaccines, the main side effects of the J&J shot are pain at the injection site and flu-like fever, fatigue and headache. No study participant experienced the severe allergic reaction, called anaphylaxis, that is a rare risk of some other Covid-19 shots, although one experienced a less serious reaction.

J&J was on track to become the world's first one-dose option until earlier this month, Mexico announced it would use a one-dose version from China's CanSino. That vaccine is made with similar technology as J&J's but initially was developed as a two-dose option until beginning a one-dose test in the fall.

READ MORE: Pakistan to allow private firms to import Covid-19 shots with no price caps

The Pfizer and Moderna vaccines now being used in the US and numerous other countries must be kept frozen, while the J&J shot can last three months in the refrigerator, making it easier to handle. AstraZeneca's vaccine, widely used in Europe, Britain and Israel, is made similarly and also requires refrigeration but takes two doses.

If the FDA clears the J&J shot for US use, it won’t boost vaccine supplies significantly right away. Only a few million doses are expected to be ready for shipping in the first week. But J&J told Congress this week that it expected to provide 20 million doses by the end of March and 100 million by summer.

European regulators and the World Health Organization also are considering J&J’s vaccine. Worldwide, the company aims to be producing around a billion doses by the end of the year.

READ MORE: Ghana receives world's first doses of free Covax vaccines – latest updates

Source: AP