A new study from researchers at Harvard University has determined which vaccine offers the best protection against COVID-19. The results of the study, which were published in the New England Journal of Medicine, found that Moderna's vaccine is slightly more effective than the one made by Pfizer.
The researchers combed over medical records of nearly 440,000 veterans who were vaccinated between January 4 and May 14, 2021. They found that those who received Pfizer's vaccine had a 27% higher risk of infection and a 70% higher risk of hospitalization than those who were vaccinated with Moderna's vaccine.
The researchers noted that most of the data was collected before the Delta variant was the dominant strain in the United States. They were able to collect some data on the Delta variant during a 12-week follow-up period and reported a higher risk of infection for people who received Pfizer's vaccine. They pointed out that the data on the Delta variant was not as precise because of the smaller number of eligible participants.
The researchers stressed that both vaccines are highly effective against COVID-19 and have an efficacy of more than 90%.
"Given the high effectiveness of both vaccines, either one is strongly recommended to any individual offered the choice between the two," said first author Barbra Dickerman, CAUSALab investigator and instructor in the Department of Epidemiology at Harvard Chan School. "However, this large-scale study allowed us to detect subtle differences between these two highly effective vaccines. While the identified differences in estimated risk were small on the absolute scale, they may be meaningful for larger decision-making bodies, such as health care systems and higher-level organizations, when considering the large population-scale at which these vaccines are deployed."
Dickerman cautioned that the study did not take into account any safety issues with the vaccines and said that her team is currently investigating any differences between the two mRNA vaccines.