Correction: March 23, 2021
This article has been revised to reflect the following correction: Due to an editing error, an earlier version of this article incorrectly contained the name of an institution. It is the Southwestern Medical Center at the University of Texas, not the Southwestern Medical Center.
More than two months after being fully vaccinated against Covid, a New York doctor woke up with a headache and a dull, heavy feeling of fatigue. Fever and chills soon followed, and her senses of taste and smell began to fade.
This, he thought, couldn’t be happening. But it was: he tested positive for the coronavirus.
“It was a huge shock,” he said. He knew that no vaccine was perfect and that the Pfizer-BioNTech injections he received had been found to be 95 percent effective in a large clinical trial. “But somehow in my mind, it was 100 percent,” he said.
The doctor, who requested anonymity to protect his privacy, is one of the few reported cases of people who have been infected after being partially or even fully vaccinated. Nearly 83 million Americans have received at least one dose of the Covid vaccine, and it is unclear how many of them will have a “breakthrough” infection, although two new reports suggest the number is very small.
One study found that only four of 8,121 fully vaccinated employees at the University of Texas Southwestern Medical Center in Dallas became infected. The other found that only seven of the 14,990 workers at UC San Diego Health and the David Geffen School of Medicine at the University of California, Los Angeles, tested positive two or more weeks after receiving a second dose of the Pfizer-BioNTech or Moderna vaccines. . . Both reports, published Tuesday in the New England Journal of Medicine, show how well vaccines work in the real world and during a period of intense transmission.
But these breakthrough cases, while quite rare, are a stark reminder that vaccinated people are not invincible, especially when the virus continues to circulate widely.
“We feel very strongly that this data should not lead people to say, ‘Let’s all get vaccinated and then we can stop wearing masks,'” said Dr. Francesca J. Torriani, infectious disease specialist at UC San Diego Health, who led the California study. “These measures must continue until a larger segment of the population is vaccinated.”
Only some of the virus-positive health workers in the California study showed symptoms, he said, and they tended to be mild, suggesting that the vaccines were protective. That echoes data from vaccine trials indicating that breakthrough infections were mild and did not require hospitalizations. Some people did not have any symptoms and they were discovered only through tests in studies or as part of their medical care.
For example, doctors at the University of North Carolina found some asymptomatic cases in vaccinated patients who were tested for coronavirus before surgery or other medical procedures, according to Dr. David Wohl, the clinic’s chief medical officer. of vaccines from that center.
He said the absence of symptoms may have meant that the vaccine was doing exactly what it is supposed to do: keep people from getting sick, even if it doesn’t completely block the virus from infecting them.
The Centers for Disease Control and Prevention has a small team that studies the most important cases, said an agency spokeswoman, Kristen Nordlund. One question researchers are considering is whether particular variants of the coronavirus could play a role in the breakthrough cases.
“Currently, there is no evidence that Covid-19 after vaccination is occurring due to changes in the virus,” Ms Nordlund said.
In the coming months, Pfizer and Moderna are expected to release data that should indicate how often vaccinated people are infected with the virus, even if they do not have symptoms. The companies have been testing participants in their vaccine trials for antibodies against a protein called N that is part of the coronavirus but not part of the vaccine. Finding those antibodies means that a vaccinated person has been infected by the virus. Some study volunteers also have their noses cleaned regularly to check for an active viral infection.
Another question is how effective vaccines are in people whose immune systems have been weakened by disease or medication, said Dr. William Schaffner, an infectious disease expert at Vanderbilt University. Revolutionary cases may occur in such people because their bodies cannot produce a robust reaction to a vaccine.
“And it’s amazing how widespread immunosuppression is,” Dr. Schaffner said. He called the condition “a testament to modern medicine,” because many patients with it are being treated successfully for conditions that not long ago would have killed them.
The doctor who fell ill in New York despite full vaccination remained in isolation at home for almost two weeks. He described his illness as relatively mild and said he was treated with monoclonal antibodies to fight the virus. “If the worst flu is a 10, this was a four,” he said.
Without the vaccine, he said, he thinks he would have been sicker.
“I would have feared for my mortality,” he said. “But I didn’t have a moment of anxiety. I didn’t think I was going to die. To think that you are not going to die, that is something very important. “
Apoorva Mandavilli contributed reporting.