This Vaccine Protects You Most Against Severe COVID, New CDC Study Says
One shot appears to be significantly more effective against hospitalizations.
Over the past few months, there have been a rising number of breakthrough COVID infections reported, from celebrities like Reba McEntire to government officials. While the vast majority of these cases are mild, there is still a small chance that vaccinated individuals can be hospitalized with COVID and even not survive an infection. With breakthrough cases, studies have found that certain factors like age and underlying conditions make you more likely to develop a severe infection, but new research has shown that which vaccine you got could play a role as well.
The Centers for Disease Control and Prevention (CDC) published a new study on Sept. 10 looking at the effectiveness of the three U.S. COVID vaccines against severe COVID amid the Delta variant. The researchers examined more than 32,000 medical encounters from 187 hospitals and 221 emergency departments and urgent care clinics across nine states from June to Aug. 2021, when Delta became the dominant strain of the virus.
According to the study, Moderna's vaccine protected study participants more against severe COVID in all medical encounters during the Delta surge. Against hospitalizations, Moderna had a vaccine efficacy of 95 percent, while Pfizer's vaccine was 80 percent effective and Johnson & Johnson's was 60 percent. In terms of preventing emergency department and urgent care visits, Moderna was 92 percent effective, while Pfizer and Johnson & Johnson were 77 and 65 percent effective, respectively.
This study echoes other recent research. A study published Aug. 30 in the Journal of the American Medical Association compared antibody response following vaccination with both Pfizer and Moderna among 2,500 health care workers from Belgium, and found that Moderna's vaccine produces twice as many antibodies as Pfizer's. Another study from the Mayo Clinic preprinted Aug. 8 found that people who received Moderna's vaccine had a two-fold risk reduction for breakthrough infection compared to the other mRNA vaccine.
The CDC did not hypothesize why Moderna may produce more protection, but the researchers from the other studies gave a few possibilities. One is that Moderna has a higher amount of the active ingredient mRNA in its vaccine than Pfizer does. Each dose of the Moderna vaccine contains 100 micrograms of vaccine, while each Pfizer dose contains just 30 micrograms. Another possibility is the differences in time internals, as there is a three-week wait between shots for Pfizer's vaccine, compared to a four-week interval for Moderna.
"Our observational study highlights that while both mRNA COVID-19 vaccines strongly protect against infection and severe disease, further evaluation of mechanisms underlying differences in their effectiveness such as dosing regimens and vaccine composition are warranted," the Mayo Clinic researchers concluded.
But being vaccinated is still more likely to protect you against severe COVID than not, the CDC researchers found. According to this study, the three vaccines were collectively 86 percent effective in preventing virus-related hospitalization. Another major study from the agency published Sept. 10 found that unvaccinated individuals were more than 10 times more likely to be hospitalized for COVID and 11 times more likely to die from the virus than those who are fully vaccinated.
"The bottom line is this: We have the scientific tools we need to turn the corner on this pandemic," CDC Director Rochelle Walensky reiterated at a White House briefing Sept. 10. "Vaccination works and will protect us from the severe complications of COVID-19."