Johnson & Johnson has filed an application seeking emergency use authorisation for its Covid-19 vaccine with the Food and Drug Administration, bringing the company one step closer to getting the first single-shot vaccine distributed in the US.

The world’s largest healthcare group said it expected to supply 100m doses to the US government in the first half of the year, boosting supplies and speeding up the vaccination rollout.

Last week, J&J published interim data that showed its vaccine had a 66 per cent efficacy rate for preventing moderate and severe disease, lower than the first shots approved from BioNTech/Pfizer and Moderna, but above the minimum bar of 50 per cent set by the US FDA. 

Paul Stoffels, chief scientific officer, said it was working with “great urgency” to make the vaccine available “as quickly as possible”. 

“Upon authorisation of our investigational Covid-19 vaccine for emergency use, we are ready to begin shipping,” he said. 

The vaccine is also being reviewed at other health authorities around the world. 

If approved, J&J would be the third Covid-19 vaccine to receive emergency use authorisation in the US, which has not yet received an application from Oxford/AstraZeneca. As well as being just one shot — in contrast to two for Moderna and BioNTech/Pfizer — it only requires regular refrigeration, not ultra-cold temperatures, so it will be easier to distribute. 

But J&J’s interim data was also a “wake-up call” about the potential need to adjust to new variants that have emerged, Anthony Fauci said, as the vaccine appeared to be less effective in South Africa, where the 501.v2 variant dominates. 

The US drugs regulator was drawing up rules which could make it faster to approve treatments and vaccines for new variants of Covid-19, the agency said on Thursday.

New, more infectious variants have spread rapidly in recent months across multiple countries as the virus adapts to greater levels of immunity among populations. One of the most concerning has been the 501.v2 strain, first identified in South Africa, which scientists believe is more resistant to both vaccines and antibody treatments.

Janet Woodcock, the acting commissioner of the FDA, said on Thursday the regulator would consider relaxing its usual authorisation rules to expedite approval of vaccines and treatments targeted specifically at those strains.

The FDA has so far insisted that vaccine makers undertake months’ worth of phase 3 clinical trials before being authorised. But Dr Woodcock said on Thursday the agency was considering loosening those demands when evaluating vaccines that are based on existing technology but specifically target the new variants.

She said: “We do not believe there will be the need to start at square one with any of these products — we recognise we are in a pandemic and we need to arm healthcare providers with the most appropriate tools to fight this pandemic on the front lines. We do not want to create obstacles to getting these tools to the front lines.”

The US has been by far the hardest hit country by the Covid-19 pandemic, registering more than 26m infections and nearly 441,000 deaths, according to data from the Covid Tracking Project. So far, more than 57m doses of Covid-19 vaccines have been distributed in the US, with 35.2m doses having been administered.

Shares in J&J added 2 per cent in after-market trading in New York.