No, Most COVID Infections Are Not Occurring in Vaccinated People - MedPage Today

Misinformation and misunderstanding about vaccine efficacy have abounded recently, potentially sparked by what seemed to be worrying data out of Provincetown, Massachusetts, reported last week by the CDC.

The agency's investigation revealed that 74% of the 469 COVID-19 cases in that outbreak occurred in fully vaccinated people.

But that doesn't by any stretch of the imagination mean that three-quarters of vaccinated people are getting COVID.

In addition to this being one particular outbreak, as vaccination rates increase overall, a larger proportion of cases will occur in the vaccinated -- it's just simple math.

Katelyn Jetelina, PhD, MPH, an epidemiologist at the University of Texas Health Science Center at Houston, explained the concept of base rate bias back in June after the Israeli health minister said that about half of infections were occurring in vaccinated people.

"The more vaccinated a population, the more we'll hear of the vaccinated getting infected," Jetelina wrote, noting that 85% of Israeli adults were vaccinated at the time.

If there were four COVID cases out of 100 people, for example, with two occurring in vaccinated people and two occurring in unvaccinated people, that would be 50% of cases occurring in vaccinated people.

But the more important number to look at would be infection rates among the separate groups -- which would be a 13% infection rate in the unvaccinated, and a much smaller infection rate of 2% in the vaccinated.

That would strongly indicate that vaccines are working.

Massachusetts's most recent data on breakthrough cases indeed indicate that vaccines are working remarkably well in that state. As of July 31, there were 7,737 breakthrough infections among 4.3 million fully vaccinated people. Of these, 395 required hospitalization, and 100 died.

With that large of a denominator, the percentages are reassuring: 0.18% of fully vaccinated people had a breakthrough infection; 0.009% went to the hospital; and 0.002% died.

While Massachusetts did not offer data on the percentage of unvaccinated people who'd been infected, hospitalized, and died, it's likely a substantial proportion, given the state's 7-day average of 870 cases daily (and given that the 7,737 breakthrough cases were a cumulative total since Jan. 19, 2021).

Yes, researchers have acknowledged that breakthrough infections are likely to be under-reported, so the CDC recently estimated that 35,000 fully vaccinated people each week develop symptomatic COVID-19.

Even at that rate, vaccination confers an eightfold reduction in the risk of getting infected in the first place; a 25-fold reduction in risk of getting hospitalized; and a 25-fold reduction in the risk for death.

"We need to make it clear that vaccination reduces your chance of getting infected with COVID-19 and thus of transmitting it," tweeted Leana Wen, MD, MPH, of George Washington University in Washington, D.C. "The key to stopping the pandemic? Vaccination!"

Last Updated August 06, 2021

• 

  Kristina Fiore leads MedPage’s enterprise & investigative reporting team. She’s been a medical journalist for more than a decade and her work has been recognized by Barlett & Steele, AHCJ, SABEW, and others. Send story tips to k.fiore@medpagetoday.com. Follow

Adblock test (Why?)

"Occur" - Google News
August 06, 2021 at 08:31PM
https://ift.tt/3jxQXoI

No, Most COVID Infections Are Not Occurring in Vaccinated People - MedPage Today
"Occur" - Google News
https://ift.tt/2Qqpsjw
Shoes Man Tutorial
Pos News Update
Meme Update
Korean Entertainment News
Japan News Update