If Pfizer’s and BioNTech’s COVID-19 vaccine was good enough to get a nod from the U.S. Food and Drug Administration, then the Moderna and National Institutes of Health vaccine almost certainly is.
The FDA on Tuesday released its detailed analysis of the performance of the Moderna vaccine (so far) in an ongoing phase 3 clinical trial involving more than 30,000 people. The bottom line: It was 94.5% effective in preventing cases of COVID-19.
An advisory group of independent scientists and other experts will review the data Thursday before voting on recommending an emergency use permit for the Moderna vaccine. An approval would pave the way for FDA authorization within days.
Like the Pfizer vaccine, the Moderna vaccine stimulates the immune system to attack the coronavirus that causes COVID-19 by delivering a fragment of the virus’s genetic code. That code – known as messenger RNA or mRNA – instructs the body to make copies of the spike protein that lines the surface of the virus. The immune system responds by producing antibodies, which remain on standby until faced with an actual infection.
Here’s a closer look at how the two vaccines stack up:
How effective are the vaccines in general?
The Moderna vaccine was 94.5% effective in the prevention of COVID-19 in those followed for an average of 7 weeks after their second dose. Five of the 13,934 study participants who received the vaccine developed COVID-19, compared with 90 of the 13,883 participants who received the placebo.
The Pfizer vaccine was 95% effective to prevent COVID-19 in those who were followed for an average of two months after receiving their second dose. Eight of the 18,198 study participants who received the vaccine developed COVID-19, compared with 162 of the 18,325 participants who received the placebo.
Were the vaccines effective in older people?
Yes.
In the phase 3 study the Moderna vaccine was 100% effective in people aged 65 and older. It was also 93.4% effective in people between the ages of 18 and 64.
In the phase 3 study the Pfizer vaccine was 93.7% effective in people aged 56 and older. It was also 95.6% effective in people between the ages of 16 and 55.
How well did the vaccines work in people with pre-existing medical conditions?
Both vaccines performed slightly better in people with pre-existing conditions that made them more vulnerable to COVID-19 than in people without.
The Moderna vaccine was 95.9% effective in people with a select group of health problems – chronic lung disease, severe heart disease, diabetes, liver disease, HIV and severe obesity. For people without these conditions, it was 94% effective.
The Pfizer vaccine was 95.3% effective in people with a wider range of health problems and 94.7% effective in people without them. In addition to the health issues addressed in the Moderna study, the Pfizer study also examined the performance of the vaccine in people with cancer, kidney disease, dementia and vascular disease, among other conditions.
Did the vaccines help people with color?
All five people in the Moderna study who developed COVID-19 after they received the vaccine were white. As a result, the Moderna vaccine was 100% effective in Black, Latino, and Asian Americans, as well as those of mixed racial backgrounds. Vaccine efficacy could not be determined for Native Americans or Pacific Islanders, as there were no cases of COVID-19 in the vaccine or placebo group.
In the phase 3 study the Pfizer vaccine was 100% effective for black study participants and 94.5% effective for Latino participants, slightly below 94.7% effectiveness for White subjects. In addition, it was 74.4% effective in Asians and 100% effective in Native Americans and Pacific Islanders. Among people described as multiracial, it was only 10.4% effective, with one case of COVID-19 among those who received the vaccine and one case among those who received the placebo.
Did the vaccines work equally well in men and women?
Both vaccines performed slightly better in men than in women.
The Moderna vaccine was 95.5% effective in men and 93.5% effective in women.
The Pfizer vaccine was 95.3% effective in men and 93.9% effective in women.
Did the vaccines prevent serious cases of COVID-19?
The Moderna vaccine was 100% effective to prevent cases of severe COVID-19. Eleven people in the study developed serious illness, and they were all in the group that received the placebo. Three of those patients were ill enough to be hospitalized.
The The Pfizer vaccine was 66.4% effective to prevent cases of severe COVID-19. Of the four study participants who developed serious illness after two injections, one had received the vaccine and three received the placebo. Two of those in the placebo group were hospitalized, including one who was admitted to an intensive care unit.
What about side effects?
Neither vaccine caused problems that would render an emergency use license unfounded, the FDA analysis showed.
Short-term pain at the injection site was very common with both vaccines. About 90% of those who received the Moderna vaccine reported such pain after their two doses, as did about 80% of those who received the Pfizer vaccine. In both studies, injection site pain was much less common in people who received the placebo.
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The most common side effects of both vaccines were fatigue, headache, muscle pain, chills, and joint pain. However, these were reported more often in the Moderna process than in the Pfizer process.
After receiving a second dose of the Moderna vaccine, 63% of study participants had headache, 68% experienced fatigue, 45% had joint pain, and 48% had chills.
In the Pfizer study, 39% of the participants had headaches, 51% experienced fatigue, 19% had joint pain, and 23% had chills after receiving their second dose of vaccine.