29/01/2021 13:19 GMT | Updated 29/01/2021 13:37 GMT

Johnson & Johnson Single Dose Covid Vaccine Proves Effective In Clinical Trials

But the pharmaceutical giant's results showed it does not work as well as some two-shot rivals.

Johnson & Johnson’s one-dose vaccine seems to protect against Covid-19, but not as well as some two-shot rivals, phase 3 trial results have shown.

The vaccine, which was trialled in both one- and two-dose regimens, is 66%effective overall at preventing moderate to severe illness, and much more protective – 85% – against the more serious symptoms. 

There was some geographic variation. The vaccine worked better in the US – 72% effective against moderate to severe Covid-19 – compared to 57% in South Africa, where it was up against an easier-to-spread mutated virus.

“Gambling on one dose was certainly worthwhile,” Dr Mathai Mammen, global research chief for J&J’s Janssen Pharmaceutical unit, told the Associated Press.

Health secretary Matt Hancock tweeted about the news, adding: “If this jab is approved [by the Medicines and Healthcare Products Regulatory Agency] this could significantly bolster our vaccination programme, especially as a single dose vaccine.” 

The single-shot vaccine has been developed by the pharmaceutical arm of the company, Janssen. 

Paul Stoffels, vice chair of the executive committee and chief scientific officer at Johnson & Johnson, said: “These top-line 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.”

Clinical trials on humans progress through three phases, with the first tests being on small groups of up to 100 people to assess the safety of a vaccine.

A pharmacist prepares vials of coronavirus vaccine (file picture) 

At a second phase, a larger group of several hundred people is used to check if a vaccine consistently works, while a third phase could involve several thousand people to gather statistically significant data on a vaccine’s safety and efficacy.

Clinical trials can normally take years, but due to the pressing need significant global investment and scientific collaboration during the pandemic has helped accelerate research processes.

It is the fifth vaccine on the market alongside formulations from Pfizer (with an efficacy rate of 95%), Moderna (94%), Oxford/AstraZeneca (70%) and Novavax (89%).