Moderna's vaccine offers better protection against COVID-19 hospitalization than Pfizer or J&J, new CDC study finds

• Moderna's COVID-19 vaccine seems to protect better against hospitalization than other US-authorized shots.
• Moderna's shot lowered the risk of hospitalization by 93%, a new CDC report found.
• Pfizer's shot lowered that risk by 88%, whereas Johnson & Johnson's shot lowered it by 71%.

Until recently, Moderna and Pfizer's COVID-19 vaccines were seen as comparable shots, offering similar protection against disease and death.

But a new report released Friday by the Centers for Disease Control and Prevention suggests that Moderna's vaccine does a better job of preventing COVID-19 hospitalizations than other vaccines authorized in the US. Both Moderna and Pfizer's vaccines, as well as one from Johnson & Johnson, offer substantially better protection than remaining unvaccinated, the report shows.

Moderna's two-dose shot lowered the risk of hospitalization by 93% from March to August, the report found. Meanwhile, Pfizer's two-dose vaccine lowered the hospitalization risk by 88% over the same time period.

The report pooled data from 21 hospital across 18 US states. It looked at about 1,300 fully vaccinated people and compared them to about 2,300 people who hadn't received shots. Of the vaccinated people, 476 got Moderna shots, 738 got Pfizer's, and 113 received J&J.

The Delta variant became dominant in the US in July, so the data may include people who got infected with Delta, Alpha, or other common strains over the last six months. (The report didn't screen for individual variants.)

The protection from Pfizer's shot declines over time

The difference in vaccine effectiveness appears to be driven by the fact that Pfizer's protection declined over time, whereas Moderna's did not, the CDC authors wrote. Pfizer's shot lowered the risk of hospitalization by 91% in the first four months after it was administered. Protection went down to 77% after four months.

Both Moderna and Pfizer's vaccines offer better protection than J&J's single-dose shot, though. That vaccine lowered the risk of hospitalization by 71% over the time period of March to August, the report found. All three vaccines still offer strong protection against severe disease and death.

The findings may "guide individual choices and policy recommendations regarding vaccine boosters," the CDC authors wrote. Indeed, some public-health experts have suggested that boosters may not be necessary for those who received Moderna's shot.

"The early evidence looks like persistence is better with Moderna, and that's why the [Biden] administration and the FDA have been suggesting that it's really more specific to people who got Pfizer who may need boosting," Chris Beyrer, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, recently told Insider.

A Food and Drug Administration external advisory panel is meeting today to decide whether to recommend a third dose of Pfizer's vaccine.

Moderna's vaccine also seems to hold up better against Delta infections

The CDC report gives a few reasons for why Moderna's vaccine seems to offer more lasting protection against hospitalization. For one, the vaccine contains a higher dose of mRNA, which may explain why Moderna's shot produced higher antibody levels than Pfizer's vaccine two to six weeks after it was administered.

Moderna's doses are also given four weeks apart, which may allow more time for antibodies to build. Pfizer's doses are given three weeks apart.

A recent UK study, which is still awaiting peer review, found that Pfizer's vaccine may have performed better with a longer dosing interval: The shot seemed to produce more antibodies when doses were administered six to 14 weeks apart as opposed to three to four weeks apart.

Other studies have also suggested that Moderna's vaccine may do a better job of preventing infections in the face of the Delta variant.

An August study from the Mayo Clinic that hasn't been peer reviewed found that Moderna's vaccine lowered the risk of a coronavirus infection by 86% in Minnesota from January to July. In July, when the Delta variant accounted for more than 70% of Minnesota's COVID-19 cases, that protection went down to 76% - a small decrease compared to Pfizer's. Pfizer's shot lowered the risk of a coronavirus infection by 76% from January to July. In July, that protection went down to 42%.