Single-dose vaccine passes early-stage international safety trials

Johnson & Johnson’s single-dose experimental coronavirus vaccine has shown it generated an immune response in early-stage trials in nearly all volunteers, with minimal side effects, after a single dose, reports CNN.

The American company expects to report details of more advanced trials later this month and is hoping to apply for emergency authorisation from the US Food and Drug Administration (FDA) soon after.

Writing in the New England Journal of Medicine, an international team of researchers who tested the vaccine in around 800 volunteers said the early-stage trials showed it was safe and probably should work.

The FDA has given emergency use authorisation to the Pfizer-BioNTech and Moderna vaccines which were both about 95% effective in their Phase 3 trials. They use messenger RNA or mRNA, a new vaccine technology.

Johnson & Johnson’s vaccine arm, Janssen, uses a different technique for its vaccine, called for now by its experimental name, Ad26.COV2.S.

It uses a weakened version of a common cold virus called adenovirus 26 to carry genetic material from the virus into the body, prompting human cells to produce pieces of the virus which are then recognised by the immune system.

A company spokesman told CNN, “An efficacious single-dose Covid-19 vaccine has obvious logistic advantages over a two-dose vaccine, especially during a pandemic.”

The company is studying whether a second dose increases efficacy or durability of the immune response.

“If the single-dose vaccine is shown to be safe and effective, the company expects to submit an application for Emergency Use Authorisation with the FDA shortly afterwards, with other regulatory applications around the world to be made subsequently,” Johnson & Johnson said.

All of the companies making coronavirus vaccines have been manufacturing millions of doses even as they test them, so they can roll them straight out should they get FDA and international authorisation.

Johnson & Johnson is contracted to deliver 100 million doses to the US government if it wins EUA from the FDA.