Moderna VS Pfizer COVID-19 vaccine

A second coronavirus vaccine has now joined the fight against COVID-19 in the United States. On December 18, the U.S. Food and Drug Administration authorized Moderna’s vaccine for emergency use in people 18 years or older. The decision follows a thumbs-up vote from a panel of experts that convened on December 17 to discuss vaccine data that the biotechnology company had collected from its ongoing clinical trial. The vaccine joins a similar one from pharmaceutical company Pfizer and its German partner BioNTech, which was authorized December 11 and has begun to be administered to people in high-risk groups in the United States, including health care workers and people living in nursing homes (SN: 12/11/20; 12/1/20). Here’s a look at how the two vaccines stack up against one another. Both clearly protect people ranging in age from 18 to older than 65 from developing COVID-19 symptoms. Both Moderna’s vaccine — developed in collaboration with the U.S. National Institutes of Health — and Pfizer’s exceeded expectations in clinical trials. In documents provided to the FDA for review, Moderna reported that their Phase III clinical trial, which includes more than 30,000 people, showed that the vaccine was 94.1 percent effective at preventing those who received it from developing COVID-19 symptoms. The biotechnology company had previously released the finding, determined two weeks after participants received a second dose of the vaccine, in a Nov. 30 news release (SN: 11/16/20). Pfizer’s vaccine is similarly effective at preventing symptoms, with an efficacy of 95 percent. The comparable results are likely because the pair of COVID-19 vaccines are “a lot more alike than they are different,” says Susanna Naggie, an infectious disease physician at Duke University. “I think that’s why we are seeing a very similar profile in terms of the early efficacy data.”

For Pfizer, that efficacy was comparable across age groups ranging from 16 to 89 years old. Among Moderna clinical trial participants aged 18 to 64 years old, the vaccine was 95.6 percent effective. But in people older than 65, it had a lower efficacy of 86.4 percent. That difference, however, is based on a small number of cases from that older age group — four in the vaccine group and 29 in the placebo group — and is not statistically significant, Jacqueline Miller, head of the Moderna’s infectious disease development, said in the Dec. 17 FDA advisory hearing. The vaccine’s “efficacy in the elderly is consistent with its efficacy in the overall population,” she said. Moderna’s vaccine might provide better protection after the first dose. While both vaccines require two doses to give people the best protection, early evidence hints that Moderna’s may do a better job fending off symptoms as early as two weeks after the first dose. Pfizer’s vaccine regimen includes two shots spaced 21 days apart; Moderna’s two doses are separated by 28 days. After people in the Pfizer trial were given their first dose, there were 39 COVID-19 cases in the vaccine group and 82 in the placebo, giving the vaccine an efficacy of 52.4 percent. Moderna’s, on the other hand, had an efficacy of 80.2 percent after the first dose. In Moderna’s trial, however, that efficacy is based on a relatively low number of cases — 39 in the placebo arm versus seven in the vaccine arm — in only a subset of the trial participants. And nearly all participants went on to receive Moderna’s second dose, making it difficult to know for sure how well people are protected from a single injection. Moderna’s vaccine may be better at preventing severe symptoms, but it’s too soon to know. Unlike Pfizer, Moderna has preliminary data that suggest its vaccine stops infection, not just symptoms. Both vaccines trigger similar side effects, though questions remain about serious allergic reactions. More doses of Moderna’s vaccine will be initially available in the United States. Moderna’s vaccine doesn’t have to be kept quite so cold, so it should be easier to distribute.

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