The recurrence of a recovered infection casts doubts on immunity against...

A study published Tuesday showed that “Covid-19” patients may face more severe symptoms the second time they are infected, thus confirming that it is possible to contract 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”, during a period of 48 days.

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 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 lead 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 recuperation of the virus, although there 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 the disease.

But it is not clear how long the antibodies to “Covid-19” 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 millions of “Covid-19” infections 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 Lancet research, Professor of Immunology, Molecular, Cellular and Developmental Biology at Yale Akiko University Iwasaka said the research findings 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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