Moderna and Pfizer's COVID-19 Vaccines Block 90% of All Infections

Now we have real-world confirmation.
Brad Bergan

The two main COVID-19 coronavirus vaccines — from Pfizer/BioNTech and Moderna — successfully prevent 90% of infections after full vaccination, according to a new study shared on the Centers for Disease Control and Prevention's (CDC's) official website.

These new results from the CDC serve as strong evidence that the primary vaccines can prevent all infections — including asymptomatic and pre-symptomatic ones — 90% of the time.

COVID-19 infections dropped by 80% after just one vaccine shot

Both Pfizer and Moderna's vaccines blocked 90% of infections two weeks after receiving the second of two full-suite doses. After the first dose of either mRNA vaccine, recipients' risk of COVID-19 coronavirus infection dropped sharply by 80% two or more weeks after the shot. This study involved 3,950 health care personnel, in addition to first responders and other essential workers, and required them to self-collect nasal swabs every week for PCR lab testing. This went on for 13 weeks, whether or not they developed symptoms of the COVID-19 illness.

This comes on the heels of Moderna and BioNTech announcing they're expanding the use of technology used to develop the COVID-19 vaccine — to help advance other therapies and vaccines — namely messenger RNA, or mRNA.

The CDC said it decided to use these test groups as participants because they showed a greater likelihood of exposure to the virus because of their professions. Since they self-swabbed once per week, researchers were able to seek out evidence of coronavirus infection regardless of symptoms. And, only 10.7% of infections were asymptomatic, according to the CDC.

However, most infections happened among those whose infections were pre-diagnoses via tests before they showed symptoms or even knew they had the virus — which is the period when transmission is most likely.

New vaccine effectiveness results match those from before FDA authorization

Notably, these latest findings are consistent with those from before the vaccines were granted emergency use authorizations from the FDA — while they were still in the companies' respective phase-3 clinical trials. And while these initial results showed a high efficacy rate against COVID-19 illness, it remained to be shown whether the vaccines really prevented infection.

Stopping both pre-symptomatic and asymptomatic infections among health care and other essential workers via vaccination will help curb the spread of the global pandemic. "This study shows that our national vaccination efforts are working," said CDC Director Rochelle Walensky, in a statement, according to a report from The Hill. "The authorized mRNA COVID-19 vaccines provided early, substantial real-world protection against infection for our nation's health care personnel, first responders, and other frontline essential workers."

"These findings should offer more hope to the millions of Americans receiving COVID-19 vaccines each day and to those who will have the opportunity to roll up their sleeves and get vaccinated in the weeks ahead. The authorized vaccines are the key tool that will help bring an end to this devastating pandemic."

It's easy to feel overwhelmed by the year-long torrent of seemingly-endless COVID-19 coronavirus updates. But even now, after it all, the measurement of the effectiveness of COVID-19 vaccines as they roll out to wider groups of the general population gives us a hint at how close we are to putting the dark years of calamity behind us.

This was a breaking story and was regularly updated as new information became available.

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