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Wake Forest researcher: There aren't a lot of vaccinated people in the hospital

Wake Forest researcher: There aren't a lot of vaccinated people in the hospital

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The rare COVID-19 breakthrough cases among vaccinated individuals have become a focal point over the past six weeks as the highly contagious delta variant continues its community spread.

As a result, “people may feel overly alarmed by the number of fully vaccinated people who are turning up among the infected,” said Lucy D’Agostino McGowan, a Wake Forest University biostatistician who uses statistical tools to answer medical questions.

So much so that some unvaccinated individuals are citing those breakthrough occurrences as a reason, if not an excuse, for not getting a dose.

That sort of talk has prompted D’Agostino McGowan to apply a mathematical approach to demonstrate why those public-health concerns and misconceptions are overdone.

“Breakthrough cases can and do happen, and the delta variant is certainly presenting new challenges,” D’Agostino McGowan said. “I want to know the probability of getting infected if I am vaccinated compared with the probability of getting infected if I am not vaccinated.

“When (the data is) looked at correctly, we see that the risk of severe illness is reduced for vaccinated individuals, and that there aren’t a lot of vaccinated people in the hospital,” she said.

D’Agostino McGowan said the confusion and misconceptions is coming mostly from “looking at the proportion of breakthrough cases among all infected, rather than among all vaccinated.”

A CNN analysis last week of federal Centers for Disease Control and Prevention supports McGowan’s viewpoint.

The analysts determined that more than 99.99% of people who are fully vaccinated against COVID-19 have not had a breakthrough case resulting in hospitalization or death.

Of the more than 164 million Americans fully vaccinated as of Aug. 2, fewer than 0.001% of those individuals, or 1,507, have died from COVID-19 related illnesses.

By comparison, the overall U.S. death total from COVID-19 related illnesses is more than 621,000, including 13,826 in North Carolina and 436 in Forsyth County.

In terms of case totals, the CDC has reported about 153,000 symptomatic breakthrough cases as of late July, which is less than one-tenth of 1% of those fully vaccinated. About 75% of those cases involve those ages 65 and older.

Proper perspective

In statistical terms, D’Agostino McGowan said “we need to flip the conditional” to gain the proper perspective.

According to Investopedia, conditional probability is defined as “the likelihood of an event or outcome occurring, based on the occurrence of a previous event or outcome.

“Conditional probability is calculated by multiplying the probability of the preceding event by the updated probability of the succeeding, or conditional, event.”

D’Agostino McGowan said that “rather than reporting the percent of people who have gotten COVID-19 or been hospitalized among vaccinated people, the reporting tends to focus on the flip — the percent of vaccinated people among those who have gotten COVID-19 or been hospitalized.”

She said that “one is useful for thinking about vaccine effectiveness and the other isn’t.

“The vaccines are very effective, but reports are not making this clear,” she said.

Other viewpoints

The CDC, as well as local and state public-health officials, have said that at least 95% of current COVID-19 cases and hospitalizations are occurring in the unvaccinated, those with just one of the two Moderna or Pfizer doses, or who are immunocompromised.

For example, Forsyth health director Joshua Swift said last week there have been few local cases of vaccinated people getting a breakthrough case of COVID-19.

“The slower we are at people getting the vaccine, the virus can get ahead and potentially mutate into something even more contagious,” Swift said.

Dr. Christopher Ohl, an infectious diseases expert at Wake Forest Baptist Health, said that when breakthrough cases do occur, they are concerning when unvaccinated and immunocompromised individuals are exposed.

Meanwhile, he said a breakthrough case between vaccinated individuals tends to produce what he is calling “a COVID cold” because it typically involves an upper respiratory tract infection that doesn’t affect the body’s organs as COVID does, “doesn’t give you pneumonia or land you in the hospital.”

Ohl said he is concerned that some vaccinated individuals are not getting tested when they show COVID-19 symptoms.

“Some people don’t want to know if they have COVID if they get sick,” Ohl said. “But, they need to get tested so we can do the contact tracing.

“That includes if you have been vaccinated because of breakthrough infections. That way you know what to do in your household and workplace ... so you don’t give it to others.

“That’s the transmission from a vaccinated person that we worry about,” Ohl said.

Other risks

D’Agostino McGowan said that for the current occurrences of breakthrough COVID-19 cases, “there could be things about the vaccinated population that makes them more vulnerable, such as age or pre-existing conditions.”

She said unvaccinated individuals are vulnerable to infection and a serious case of COVID-19 regardless if they are exposed to someone vaccinated with a breakthrough case or unvaccinated.

D’Agostino McGowan said she understands those who have vaccinated may be getting frustrated because they are being asked to be more cautious in public setting primarily to protect the unvaccinated.

“When I am thinking about being more careful, I am thinking about in the context of those under age 12 who don’t have the option to be vaccinated,” D’Agostino McGowan said.

“I can see the frustration where it feels like people are having to change behavior for a group of people choosing not to be vaccinated. But there are a large number of people who are not making that choice, but just don’t have another (medical) option at this point.

“It’s worthwhile to be cautious for that group, too,” she said. “The best thing you can do to keep yourself and your community safer is get vaccinated.”


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