Moderna vaccine highly effective five months after second dose: Study

The Moderna vaccine offers an effectiveness of 87 per cent in preventing COVID-19 infection, over 95 per cent against severe disease, and 98 per cent against death, according to a study.

The research, published in the journal The Lancet Regional Health-Americas, evaluated the five-month effectiveness of the Moderna COVID-19 mRNA vaccine as part of an observational study.

Funded by Moderna, the study included 352,878 recipients of two doses of the vaccine matched to 352,878 unvaccinated individuals by age, sex, race and ethnicity. 

“This research provides reassuring evidence of the high effectiveness of the Moderna COVID-19 vaccine in preventing infection, hospitalisation, and death from COVID-19,” said Katia Bruxvoort, an adjunct investigator with Kaiser Permanente, an integrated health care organisation in Southern California, US.

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“One of the important aspects of this study was that it included more than 700,000 adults who were racially and ethnically diverse and had a broad range of underlying conditions including chronic diseases, immunocompromising conditions, and autoimmune conditions,” Bruxvoort said.

In the study, vaccinated individuals received two doses of the vaccine from December 18, 2020, to March 31, 2021. Individuals in both groups were followed until June 30, 2021. During follow-up, COVID-19 infections occurred among 289 vaccinated patients and 1,144 unvaccinated patients.

The researchers found that the vaccine effectiveness against COVID-19 infection was 87 per cent. COVID-19 hospitalisation occurred among 13 vaccinated and 182 unvaccinated patients, and in-hospital deaths occurred among 1 vaccinated and 25 unvaccinated patients, they said.

Vaccine effectiveness was 96 per cent against COVID-19 hospitalisation, and 98 per cent against in-hospital deaths, according to the researchers. Vaccine effectiveness against COVID-19 infection remained high across age, sex, racial, and ethnic subgroups, with results ranging from 83 to 92 per cent, they said.

“This study adds evidence of real-world Moderna COVID-19 vaccine effectiveness, particularly among the general population,” said Hung Fu Tseng, a researcher with the Kaiser Permanente, and the senior author of the study.

“Additionally, our follow-up on these fully vaccinated patients occurred through June 2021, a period that overlapped with the emergence of the Delta variant in the US. Long-term follow-up is ongoing to further evaluate the durability of protection.”

Also read: Omicron may be more contagious, South Africa cases double in a day

Earlier this week, Stephane Bancel, CEO of Moderna, told a newspaper that that there was likely to be a “material drop” in the effectiveness of vaccines against Omicron.

“I think it is going to be a material drop. I just don’t know how much because we need to wait for the data. But all the scientists I have talked to… are like, ‘This is not going to be good,’” he told Financial Times.