CDC Study Shows Pfizer and Moderna Vaccines 90 Percent Effective in Preventing Infection After Second Dose

The new real-world study from the CDC further strengthens the recommendation that all those who are eligible get fully vaccinated as soon as possible.

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For the latest shot of cautious optimism amid concerningly premature rushes to shedded pandemic mitigation efforts, we once again turn to the CDC.

Early Monday, the health agency shared some promising findings from a real-world study comprised of health care personnel, first responders, and other essential and frontline workers. Estimated messenger RNA (mRNA) vaccine effectiveness for prevention of infection was found to be 90 percent for those fully immunized and 80 percent for those partially immunized, i.e. those who had received one shot of a two-shot dose.

“These interim vaccine effectiveness findings for both Pfizer-BioNTech’s and Moderna’s mRNA vaccines in real-world conditions complement and expand upon the vaccine effectiveness estimates from other recent studies and demonstrate that current vaccination efforts are resulting in substantial preventive benefits among working-age adults,” the CDC said when publishing the study, adding that these findings also “reinforce” their recommendation that everyone receive a full two-dose immunization with mRNA vaccine options.

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Those who participated in the study were located in eight different cities around the country and were asked to complete weekly SARS-CoV-2 testing for 13 weeks in a row. Regions featured in the study included cities in Florida, Minnesota, Oregon, Texas, Utah, and multiple cities in Arizona.

Previously, mRNA COVID-19 vaccines had been shown to be effective in preventing symptomatic infections in randomized placebo-controlled trials. This new study shows that authorized mRNA vaccines are also effective in preventing infections in real-world conditions, which—though no one should need this to be reiterated to them at this point—further strengthens the recommendation that everyone should indeed get vaccinated.

Amid urgings from Dr. Anthony Fauci and other health leaders for Americans to avoid hastily abandoning mitigation policies, the Biden administration has ramped up the vaccine rollout by putting billions of dollars into expansion efforts ahead of a planned open-availability launch on May 1.

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