With one in four adults in the United States now fully vaccinated against COVID-19, health and scientific studies have documented what is known as “discovery” cases or people who have become infected or ill despite vaccination. .
Such cases are exceptionally rare, but to be expected, experts say.
“You will see revolutionary infections in any vaccination when you vaccinate literally tens, tens and tens of millions of people,” Dr. Anthony Fauci said at a March 26 White House press briefing. “In some ways, it’s not surprising,” Fauci said.
COVID-19 vaccines are extremely effective – but none are 100% effective, which means that a small number of people could become infected after full vaccination – but those infections are usually mild or asymptomatic.
Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center, called the efficacy rates of about 95% for Pfizer and Moderna vaccines “spectacularly effective.” In clinical trials, vaccines were virtually 100% effective in keeping people out of the hospital, he added, noting that “there were still some milder infections that occurred.”
How common are COVID-19 “discovery” cases?
“It’s quite rare,” said Dr. Shira Abeles, an infectious disease specialist at UC San Diego Health, about cases of discovery. “I think it will stay that way,” she added.
Recent real-world studies have confirmed this low discovery rate. Research that Abeles helped conduct in Southern California between December 2020 and February 2021 found that less than 1% of the 36,600 health workers who were studied tested positive for COVID-19 after vaccination. complete, which means both doses plus two weeks for build up immunity – with Pfizer or Moderna vaccines.
No vaccinated worker who contracted COVID-19 was hospitalized or died, and those who became ill did not appear to have milder symptoms than those who were not vaccinated, according to the researchers.
An even larger survey by the Washington State Department of Health found that out of 1.2 million people who were completely vaccinated, there was evidence of 102 cases of discovery, representing less than 0.01% of fully vaccinated state residents. While most patients had mild symptoms, at least eight were hospitalized, and the health department is investigating two potential discovery cases in which patients died.
How do COVID-19 “discoveries” happen?
It is not completely clear.
People who are very elderly or immunocompromised may be at higher risk for exposure, as their bodies may produce a less strong immune response to the vaccine.
“For every vaccine we use, immunocompromised people and the elderly do not respond as well as healthy people and younger people,” said Schaffner. In the Washington State investigation into the two potential deaths from COVID, both patients were over 80 years old and had underlying health problems.
Similar to the flu, the increased risk for the elderly and immunocompromised is one of the reasons why it is important for young and healthy people to receive the COVID-19 vaccine. If everyone is vaccinated, it is harder for the virus to find targets, which protects those at higher risk.
“We should all be vaccinated to protect ourselves, as well as to protect the weakest of us,” Schaffner said.
As for cases of discovery among young or healthy people, “from time to time, something happens for biological reasons that we cannot explain,” Schaffner said.
Those who become ill after full vaccination should still have partial protection. Instead of going to the hospital or dying, they may have less severe symptoms, such as a lowering sensation or the development of a slight fever. “This is the strength of our study,” Abeles said. “We were screening a population, so we took over asymptomatic diseases and mild diseases,” she said. – Generally, that’s what you’ll see.
Could new variants cause cases of “discovery”?
Another possibility that public health officials are investigating is whether the new variants of the virus have caused some of the reported cases of discovery.
“One of the important things that will be done and needs to be done is sequencing the genome of the virus, which is the virus of discovery,” Fauci said. “It would be very important to see if they entered with the wild-type virus, which would indicate a real decrease in immunity or if they would enter with one of the variants, which would be much more explicable if they do not have enough cross-reactivity. “
To date, it appears that currently authorized vaccines reduce the severity of infection regardless of the strain of the virus. This is why experts say it is extremely important that people previously infected with COVID be vaccinated. Knowing if the discovery cases were caused by the virus, the vaccines were designed to protect against or new variants could inform scientists on how to address future vaccinations and booster vaccines. If a variant of concern spreads, scientists in the lab could develop a vaccine that targets the variant’s peak protein mutations, Abeles explained. If the virus is one to which the community has already been exposed and it appears that immunity is declining, health experts could suggest a recall of the same vaccine, she added.
“It’s a moving target and we’re still learning so much,” Abeles said. “We’ll be very careful.”
In the meantime, it is crucial to keep infection levels low so that there is less evolutionary pressure on the virus to move into more worrying variants. “We want to keep only a few, rather than let the virus have too many opportunities,” Abeles said.
Morgan Winsor of ABC News contributed to the report.