The first confirmed cases of Americans who received COVID-19 twice could be re-infected with the coronavirus, with little but increased evidence that they could be more ill than they were during the first attack. I have.
A 25-year-old Nevada man with no known immune problems was infected with mild COVID-19 in April. About a month later, he was diagnosed again and required hospitalization and oxygen, according to a report released on Monday for the Lancet infection.
The authors state that at least three other confirmed cases have been published worldwide, including the first case in Hong Kong just two months ago. However, the COVID-19 reinfection tracker of BNO News, an international communications company headquartered in the Netherlands, describes the Nevada case and 22 cases, including one death.
To confirm reinfection, the DNA sequence of the respiratory sample should reveal two slightly different variants of the virus. This indicates that the second infection is not just a wreckage or reactivation of the first infection. This type of analysis rarely occurs due to cost concerns, because the respiratory samples used for diagnosis are rarely preserved for later genetic analysis.
It’s hard to say how rare reinfection is, but it complicates the question about the strength and length of natural defense immunity. The role of vaccines in boosting immunity; and wants “herd immunity”. Community-wide or herd protection occurs when either infection or vaccination causes a sufficient number of people to immunize and reduce the likelihood of spread of the disease.
Akiko Iwasaki, an immunologist at Yale University School of Medicine, said in a commentary accompanying the new study that “cases of reinfection cannot rely on immunity acquired by natural infection to provide herd immunity. It shows. ” “Herd immunity requires safe and effective vaccines and strong vaccinations.”
However, the authors of a study led by biostatistician Richard L. Tillet of the University of Nevada said that “because influenza regularly presents challenges in effective vaccine design,” we can rely on vaccines for complete protection. He points out that he may not be able to. Recent studies have shown that vaccination against seasonal flu reduces the risk of illness by 40% to 60%.
Infection with certain viruses, such as measles, causes lifelong immunity. In contrast, the seasonal coronavirus, which causes the common cold, probably provides only short-term protection of 3-4 months. After that, the antibodies that fight the disease created by the immune system to fight the invaders disappear.
If the new coronavirus, which appeared in China 10 months ago, gives limited immunity, the vaccine may enhance this protection by activating other parts of the immune system. Several vaccines currently under development have been shown to activate T cells, a more complex line of defense than antibodies.
Does that mean that each variant requires a vaccine, as the new coronavirus is mutated to have slightly different variations that can cause reinfection?
Iwasaki said that, at least so far, re-infected people have shown an immune response to the second infection, suggesting that the virus has not developed a way to circumvent the immune defense. I think the answer is no.
“Currently, there is no evidence that mutants have emerged as a result of immune evasion,” she wrote. “For now, one vaccine is sufficient to provide protection against all circulating variants.”
The authors conclude with calm observations. Without “comprehensive genome sequencing” of positive cases around the world, detection of re-infected cases would be very limited. The result is “not only to diagnose COVID-19, but also to exacerbate inadequate surveillance activities to track genetic changes in the virus.”
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