Study says less than 1% of people end up with COVID-19 after being fully vaccinated

MILWAUKEE (CBS 58) -- A new study released Wednesday show less than one-percent of fully vaccinated people ended up getting infected with COVID-19, known as breakthrough infections.

Clinical trials show Moderna and Pfizer have around 95-percent effectiveness, and Johnson & Johnson in the 70-percent range, but with millions of shots already given out, doctors say the efficacy may even be higher than expected.

“Now that they’ve been given to a much larger population, millions and millions of people, they’re performing even better,” said Dr. Ben Weston, associate professor at the Medical College of Wisconsin and medical director at Milwaukee County Office of Emergency Management.

The Wisconsin Department of Health Services says they are tracking breakthrough infections in the state and reporting to the U.S. Centers for Disease Control, the CDC reportedly seeing less than 6,000 cases in more than 84 million people fully vaccinated in the U.S.

“Of the more than 75 million people who’ve been fully vaccinated in the United States, the CDC found that less than 1-percent, in fact—way less than 1-percent have reported becoming infected,” Dr. Weston adds.

“Breakthrough infections are rare and the majority are asymptomatic or mild,” said Dr. Ryan Westergaard, chief medical officer at Wisconsin DHS.

Doctors say while severe illness and death have been reported in people who are fully vaccinated, the probability is dramatically less than people who are unvaccinated.

“So when it comes to preventing severe disease in particular, these vaccines are tremendously, tremendously effective,” adds Dr. Westergaard.  

“Another study out of the New England Journal of Medicine found a less than 1-percent breakthrough infection rate when studying hundreds of vaccinated people,” says Dr. Weston.

The New England Journal of Medicine study showed only two out of 417 people were infected after receiving both doses, or less than half a percent.

Dr. Westergaard says data published by the CDC’s Morbidity and Mortality Weekly Report from the Chicago Health Department found a majority of breakthrough infections happen in places that test routinely.

“They tend to be in settings where people are screened periodically in the absence of symptoms such as nursing homes for example,” Dr. Westergaard said.

As demand begins to slow down and federal resources plan to dwindle in Milwaukee, Mayor Tom Barrett is encouraging people get vaccinated sooner than later.

“We’re hard pressed to say—'yes continue to give us these resources’ if the demand isn’t there, and so that’s why we keep beating the drum please get the shots,” adds Mayor Barrett.

Dr. Westergaard says even if we don’t reach 80-percent herd immunity, at the end of the day every person who gets a vaccine is contributing to saving lives.