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The United Nations health agency warned that there is no scientific evidence to show that people who recovered from the coronavirus develop immunity against possible infections in the future, as the global death toll from COVID-19 exceeded 200,000 on Saturday in average of 2.8 million infections.
The World Health Organization (WHO) issued the warning when several countries consider issuing so-called “immunity passports” to people who have recovered from COVID-19, the disease caused by the coronavirus.
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The WHO said such a move could increase transmission of the new coronavirus as people who have recovered may ignore advice about taking standard precautions against the virus.
“Some governments have suggested that detecting antibodies against SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for a ‘immunity passport’ or ‘risk-free certificate’ that would allow people to travel or go back to work assuming they are protected from reinfection, “the WHO said.
“There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.”
The UN health agency issued the warning when the coronavirus pandemic reached a grim new milestone when the death toll exceeded 200,000 worldwide. The United States has seen the highest number of fatalities, with a number of deaths rising from 50,000 earlier this week, while Italy, Spain, France and the United Kingdom have reported a total of more than 20,000.
Several governments have proposed a gradual return to work, as restrictions on movements to stem the spread of the virus have paralyzed economies around the world.
Last week, Chile announced plans to give “health passports” to patients who have recovered from COVID-19. Once the presence of antibodies is verified, they will be allowed to return to work, authorities said.
“We understand the intention to try to see who can safely return to work or who could be free from the risk of infecting other people.” WHO spokesman Tarik Jaserevic he said to Al Jazeera. “But unfortunately, from a scientific point of view, we just don’t know if a person who has been infected with the coronavirus receives this immunity, and if a person receives this immunity, how long will it last.”
The WHO also believes that the serological tests currently used to detect the presence of antibodies “need additional validation to determine their precision and reliability.”
In particular, the tests should be able to distinguish between the immune response to the new coronavirus from the antibodies produced during an infection from the other six known human coronaviruses, four of which are widespread and cause mild colds.
The other two are responsible for MERS (Middle East Respiratory Syndrome) and SARS (Severe Acute Respiratory Syndrome).
“People infected with one or the other of these viruses are capable of producing antibodies that interact with antibodies produced in response to infection caused by SARS-CoV-2,” said the WHO.
Caryn Bern, a professor of epidemiology and biostatistics at the University of California, San Francisco School of Medicine, works with a team to investigate the effectiveness of antibody tests.
“Our data seems to suggest that some of the tests being used may give a fairly accurate picture of exposure and infection at the population level. What we do not yet know is whether these types of antibodies, IGM and IGG, correlate with antibodies that would be a protection against future infections that are generally called neutralizing antibodies. That is work that still needs to be done, “he told Al Jazeera.
“We are approaching this in the same way that we would be with a new strain of influenza and of course that is the problem; nobody has immunity to start with and we still don’t fully understand if people become immune. There is probably immunity, but we don’t have it I don’t understand yet, we don’t know how long it will last.
“Antibody testing is a tool that we can use to assess population exposure rates. We already know that in hot spots, like areas outside of Boston, a very large percentage, 25 percent or 30 percent percent of the people who were examined tested positive for these antibody tests. It is less of a tool for individuals than for populations, “he added.
SOURCE:
Al Jazeera and news agencies
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