COVID-19: Moderna vaccine shows 94.1 per cent efficacy in trial, according to study

Most countries are in a race to secure the best possible vaccine for COVID-19. The ongoing phase 3 clinical trial of US biotechnology company Moderna’s coronavirus vaccine has revealed 94.1 per cent efficacy in preventing symptomatic infections and severe illness, according to a peer-reviewed study.

The study, published on Wednesday (December 30) in The New England Journal of Medicine, found that in more than 30,000 participants randomised to receive the vaccine or a placebo, 11 in the vaccine group developed symptomatic COVID-19 compared to 185 participants who received the placebo.

The researchers said this demonstrates 94.1 per cent efficacy in preventing symptomatic COVID-19, adding that cases of severe disease occurred only in participants who received the placebo.

“Our work continues. Over the next months, we'll have increasing amounts of data to better define how this vaccine works, but the results so far show a 94.1 per cent efficacy. These numbers are compelling,” said Lindsey Baden, an infectious diseases specialist at the Brigham and Women's Hospital in the US where the trial took place, was quoted as saying by news agency PTI.

“And, importantly, the data suggest protection from severe illness, indicating that the vaccine could have an impact on preventing hospitalisations and deaths, at least in the first several months post-vaccination,” said Baden, co-principal investigator for the study, and lead author of the paper.

The study enrolled 30,420 adult participants at 99 sites in the US, including over 600 participants enrolled at the Brigham.

Eligible participants were 18 years old or more with no known history of SARS-CoV-2 infection, and whose locations or circumstances put them at appreciable risk of the infection and high risk of severe COVID-19, the researchers said.

They noted that the race and ethnicity proportion of the trial was 79 per cent white, 10 per cent Black or African American, and 20 per cent Hispanic or Latino participants.

The participants received their first injection between July 27 and October 23, followed by a second shot 28 days later.

In the placebo group, 185 participants developed symptomatic COVID-19 illness whereas in the vaccine group, only 11 participants did.

The researchers said overall, reactions to the vaccine were mild -- about half of recipients experienced fatigue, muscle aches, joint pain and headaches, more so after the second dose.

Baden said while these results are encouraging, they are limited by the short duration of follow-up so far.