Two reports of so-called coronavirus breakthrough infections – in which individuals who are fully vaccinated are struggling – suggest that the vaccines still offer strong protection against serious diseases, even if there are different variants.
The cases, reported Wednesday in the New England Journal of Medicine, were in two women out of more than 400 participants in the fully vaccinated study, which was tested weekly for Covid-19. Both women developed mild cases of the disease and recovered quickly.
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The co-author of the study, Dr. Robert Darnell, a professor and senior physician at Rockefeller University in New York, said the two cases are not a cause for concern.
“They definitely do not need to be hospitalized,” he said. “They had home cases of Covid-19.”
As the number of people who are fully vaccinated increases in the United States, so will reports of breakthrough infections. Last Friday, the Centers for Disease Control and Prevention said they had received reports of approximately 5,800 breakthrough infections from more than 77 million people who had been fully vaccinated.
Breakthrough infections can occur because no vaccine is 100 percent effective. Nevertheless, such cases remain very rare.
CDC officials are gathering more information on breakthrough cases to determine if patterns exist among patients. One of the questions the agency asks is whether certain variants are more likely to play a role in breakthrough cases.
Both cases were followed up in the New England Journal of Medicine report, and both cases were found to share certain mutations with the variants first identified in the United Kingdom and New York. None contained all the mutations corresponding to these previously identified variants. (Variants of the virus can contain a number of mutations.)
However, experts warn that because the report contains only two cases, it is too early to draw conclusions about which variants are most likely to lead to breakthrough infections.
One of the samples contains a mutation called E484K, which is also found in the variants of South Africa, Brazil and New York City, and it is thought to help evade the virus’ immune response to some extent.
Jeremy Kamil, a virologist at LSU Health Shreveport, said he was not surprised that this mutation was detected, as laboratory data suggest it would play a role in breakthrough cases.
“If you were to ask scientists what mutations you would expect to see in a breakthrough infection, I think the number 1 answer you would get would be E484K,” says Kamil, who was not involved in the new study.
Two studies published in the CDC’s Weekly Morbidity and Mortality Report also touched on the breakthrough infections in nursing homes on Wednesday. One report identified 22 breakthrough infections in 78 nursing homes in Chicago, which completely vaccinated nearly 15,000 residents and staff from December to March. In two-thirds of the breakthrough cases, the infections were asymptomatic, although several people developed mild to moderate symptoms, the report said. Two patients were admitted to the hospital and one individual died.
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The second report focused in March on a Covid-19 outbreak at a nursing home in Kentucky. Twenty-six residents and 20 staff members tested positive, including 18 residents and four staff members who were fully vaccinated. Sequence of cases detected the same E484K mutation as in the cases in New York.
However, those who were vaccinated were still 87 percent less likely to develop symptoms compared to those who were not vaccinated.
“The results of this study are very telling that vaccination has led to a reduced likelihood of infection and symptomatic diseases in a high-risk population,” such as a nursing home, said Jason Kindrachuk, an assistant professor of medical microbiology and infectious diseases. the University of Manitoba, said. in Winnipeg.
The women described in the New England Journal of Medicine report also have mild symptoms, said Kindrachuk, who was not involved in the new reports. “The vaccines did exactly what we adopted based on the clinical trial data and the actual world data: they are protected against serious diseases.”
One of the patients from the New England Journal of Medicine report, a healthy 51-year-old woman, tested positive for Covid-19 on March 10, 19 days after her second dose of Moderna vaccine. She said she followed guidelines, including masking and social distance, but developed symptoms, including sore throat, congestion and headaches. The day after her test, she lost her sense of smell. All her symptoms disappeared a week later.
The second patient, a 65-year-old woman without risk factors for severe Covid-19, tested positive on March 17, 36 days after her second dose of Pfizer-BioNTech vaccine. She became ill two weeks after Covid-19 was diagnosed in her unvaccinated partner.
Her symptoms include fatigue, sinus congestion and headaches. As in the first case, her symptoms disappeared after a few days.
Although CDC data suggest breakthrough infections are rare, Darnell said it would be wise to have fully vaccinated people tested for Covid-19 if they develop symptoms similar to the disease.
“If you get sick after vaccination, and it looks like, it smells and sounds like Covid-19, it could be Covid-19,” he said.
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