A Centers for Disease Control and Prevention (CDC) study released Friday found the Moderna vaccine to be the most effective against COVID-19 hospitalization, although all three vaccines provided “substantial protection.”
Researchers calculated Moderna’s vaccine effectiveness against hospitalization was 93 percent, while the effectiveness of the Pfizer-BioNTech and Johnson & Johnson vaccines was 88 percent and 71 percent, respectively.
“Although these real-world data suggest some variation in levels of protection by vaccine, all FDA-approved or authorized COVID-19 vaccines provide substantial protection against COVID-19 hospitalization,” the report said.
The study involved more than 3,600 adults who were hospitalized at 21 U.S. hospitals across 18 states between March 11 and Aug. 15. Out of those, 1,682 received positive COVID-19 test results, while the others were considered controls. Immunocompromised adults were not included in the research.
Most of the participants — 64 percent — were unvaccinated. Almost 13 percent were fully vaccinated with the Moderna vaccine, 20 percent were fully vaccinated with the Pfizer shot and 3.1 percent were fully vaccinated with the Johnson & Johnson dose.
Vaccine effectiveness among Moderna recipients hit 93 percent between 14 to 120 days after the second dose and dropped slightly to 92 percent after about four months.
But researchers documented a larger decline in effectiveness among Pfizer-BioNTech recipients, which contributed to the lower overall vaccine effectiveness. The Pfizer shots were considered 91 percent effective between 14 to 120 days after the second shot and just 77 percent after 120 days.
The scientists said the apparent higher effectiveness of the Moderna regimen after about four months could be because of higher mRNA content in the Moderna vaccine or the difference between the timing between doses. Recipients of Moderna get their second dose after four weeks, while Pfizer-BioNTech recipients get theirs after three weeks.
The study also analyzed antibody levels in 100 healthy volunteers at three hospitals two to six weeks after vaccination and found anti-RBD antibody levels higher in the Moderna vaccine than the other two products. The measure of IgG antibodies was similar in Moderna and Pfizer vaccine recipients, which were higher than Johnson & Johnson recipients.
The CDC wrote that the data suggests both mRNA vaccines, Moderna and Pfizer-BioNTech, “provide more protection” than the Johnson & Johnson shot. Figuring out the effectiveness could potentially effect policy recommendations on booster shots, the agency noted.
The Moderna vaccine was granted for emergency use in December, shortly after the Pfizer-BioNTech’s emergency use authorization. But the Pfizer-BioNTech regimen has received full approval last month, meaning it can be administered after the public health emergency ends.
Johnson & Johnson earned its emergency use authorization in late February.