A recovered infection casts doubts on immunity against Covid 19

Paris: A study published Tuesday showed that Covid-19 patients may face more severe symptoms the second time they are infected, confirming that it is possible to catch the emerging corona virus more than once.

The study, published in the Lancet Infectious Diseases journal, documents the first confirmed case of the virus returning to recovered from Covid-19 in the United States, the country most affected by the pandemic in the world, and indicates that infection with the virus may not guarantee future immunity.

The patient, a 25-year-old man from Nevada, contracted two different strains of SARS-Cove-2, the virus that causes Covid-19, within a 48-day period.

The symptoms of the second infection were more severe than the first, and they forced the patient to receive hospital treatment and oxygen assistance.

The study indicated four other recovered cases of the virus that were confirmed worldwide, in Belgium, the Netherlands, Hong Kong and Ecuador.

Experts said that the chances of the virus returning to recovering may have major implications for the world’s efforts to combat the epidemic.

It could particularly affect efforts to find a vaccine, one of the pharmaceutical companies’ most important research goals.

The return of infection has not been scientifically explained until now

“The potential for recurrence may have important implications for our understanding of immunity from Covid-19, especially in the absence of an effective vaccine,” said Mark Banduri of Nevada State Public Health Laboratories and the senior author of the study.

He added, “We need more research to find out the duration of immunity for people who have contracted SARS-Cove-2, and why some cases of the virus returning to recovering, although they are few, are more severe.”

Vaccines work by stimulating the natural response of the body’s immune system to certain pathogens, and by arming it with antibodies to combat future waves of disease.

But it is not clear how long the COVID-19 antibodies will last.

For diseases like measles, having it gives the body lifelong immunity. As for other diseases, patients may get transient immunity at best.

The study authors said that the patient in the United States may have been exposed to a very large viral load in his second infection, which caused more severe symptoms. Or it may be a more virulent viral strain.

Another hypothesis may be known as the enhanced dependence mechanism on antibodies, that is, when the antibodies make the symptoms of reinfection worse, such as the case of dengue fever.

Research indicates that recurrence of infection in any form seldom occurs, with a number of confirmed cases among the millions of cases of Covid-19 worldwide.

But since many cases of infection do not appear asymptomatic and therefore it is unlikely that the results of the tests were positive at first, it may be impossible to know whether a case of Covid-19 infection is the first or second.

In a link attached to the research by The Lancet, Professor of Immunology, Molecular, Cellular and Developmental Biology at Yale Akiko University Iwasaka said the findings of the research could influence public health measures.

“This information is essential in knowing which vaccines are capable of crossing that threshold and conferring individual and group immunity (herd immunity),” said Iwasaka, who was not involved in the research.

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