Two reports of so-called coronavirus breakthrough infections – where fully vaccinated people have the illness anyway – suggest that the vaccines still offer strong protection against serious disease even age in the face of variations.
The cases, detailed Wednesday in the New England Journal of Medicine, were cases of two women out of more than 400 fully vaccinated study participants who were tested for Covid-19 weekly. Both women developed mild cases and recovered quickly.
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The study’s co-author, Dr. Robert Darnell, a professor and senior physician at Rockefeller University in New York City, says both cases are not frightening.
“There was definitely no need to go to hospital,” he said. “They had cases at home from Covid-19.”
As the number of fully vaccinated people increases in the US, so too will reports of breakthrough infections. The Centers for Disease Control and Prevention said Friday that they had received reports of approximately 5,800 cutaneous infections from more than 77 million fully vaccinated people.
Innovative infections can occur because there is no 100 percent effective vaccine. Such cases are still very rare.
CDC officials are collecting more data on innovative cases to determine if there are any patterns. Questions include whether certain variants are more likely to play a role in innovative cases.
Both cases were followed up in the new report, and both were found to share specific mutations with the variants first identified in the UK and New York. However, neither included all the mutations to match the variations previously identified. (Variants of the virus can include several mutations.)
Experts warned that because the report details only two cases, it is too early to draw conclusions about which variants are most likely to lead to innovative infections.
One of the samples contained a mutation called E484K, which is also found in the variants of South Africa, Brazil and New York City. It is thought to help the virus to partially suppress the body’s immune response.
Jeremy Kamil, a virologist at LSU Health Shreveport in Louisiana, said he was not surprised that the mutation was detected, as lab data suggests it would play a role in groundbreaking cases.
“If you ask scientists what mutations you would expect to see in a pioneering infection, I think the No. 1 answer you would get would be E484K,” said Kamil, who was not part of the a new study.
Two other studies, published Wednesday in the CDC’s Morbidity and Mortality Weekly Report, touched on innovative infections in nursing homes. One report identified 22 pioneering infections across 78 nursing homes in the Chicago area, which fully vaccinated nearly 15,000 residents and staff members between December and March. In two-thirds of the pioneering cases, the infections were disproportionate, although several people developed mild to moderate symptoms, the report said. Two patients were hospitalized, and one person died.
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The second report focused on a case of Covid-19 in a nursing home in Kentucky in March. Twenty-six residents and 20 staff members tested positive, including 18 residents and four fully vaccinated staff. Sequencing of the cases found the same E484K mutation as in the New York cases.
However, those who were vaccinated were 87 percent less likely to develop symptoms than those who had not.
“The results of this study are quite shocking that vaccination has reduced the likelihood of infection and symptomatic disease in a high-risk population” as a nursing home, said Jason Kindrachuk, an assistant professor of medical microbiology and infectious diseases at the University of Manitoba in Winnipeg.
Similarly, the women described in the New England Journal of Medicine report also had mild symptoms, said Kindrachuk, who was not involved in the new reports. “The vaccines did exactly what we had assumed based on clinical trial and real-world data: They protected us from serious disease.”
One of the patients in 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 the Moderna vaccine. She said she followed guidelines, including masking and social distance, but was still developing symptoms, including sore throat, congestion and headaches. The day after her test, she lost her sense of smell. All his symptoms went away a week later.
The second patient, a 65-year-old woman with no risk factors for severe Covid-19, tested positive on March 17, 36 days after her second dose of the Pfizer-BioNTech vaccine. She became ill two weeks after her unvaccinated partner was diagnosed with Covid-19.
His symptoms included fatigue, sinus congestion and headache. As in the first case, his symptoms went away after only a few days.
While data from the CDC suggests that breakthrough infections are rare, Darnell said it would be wise for people who are fully vaccinated to be tested for Covid-19 if they develop symptoms similar to the illness.
“If you get sick after vaccination and it looks like, smells and sounds like Covid-19, it could be Covid-19,” he said.
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