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In a report published Friday night (24), the institution warns that “there is no evidence” that the patients who recovered have antibodies
WHO technical report
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04/25/2020 – 12:16
The WHO (World Health Organization) said on Friday (24) that there is not yet enough scientific evidence to say that people who have recovered from the new coronavirus They are immune to disease.
The statement refers especially to government officials who have advocated the creation of a “immunity passport“or” zero risk certificate “for recovered patients to be excluded from mobility restriction measures during the covid-19 pandemic.
This measure has already been cited by the Minister of Economy, Paulo Guedes, as a way to resume non-essential activities in places that have adopted measures of social isolation.
“People who assume they are immune to a second infection because they received a positive test result may ignore public health advice. Therefore, the use of such certificates can increase the risks of continuous transmission,” says the organization.
The agency notes that developing immunity to a disease through a natural infection is a multi-step process, which generally takes one to two weeks. However, it considers that until April 24, no study concluded that the presence of antibodies confers immunity to the new coronavirus in humans.
“The WHO continues to review the evidence for antibody responses to SARS-CoV-2 (covid-19 virus) infection. Most of these studies show that people who have recovered from the infection have antibodies to the virus.” said the statement. . “However, some of these people have very low levels of neutralizing antibodies in their blood, suggesting that cellular immunity may also be critical to recovery.”
“Laboratory tests that detect antibodies to SARS-CoV-2 in people, including rapid immunodiagnostic tests, need additional validation to determine their precision and reliability,” says the WHO.
“Inaccurate immunodiagnostic tests can falsely categorize people in two ways. The first is that they can falsely label people who have been infected as negative, and the second is that people who have not been infected are falsely labeled as positive. Both errors have serious consequences and will affect control efforts. “
The WHO also notes that tests must distinguish SARS-CoV-2 from the other six known human coronaviruses (of which four cause the common cold and have wide worldwide circulation, while the other two cause Respiratory Syndrome in the Middle East and Severe Acute Respiratory Syndrome). “People infected with any of these viruses can produce antibodies that cross-react with antibodies produced in response to SARS-CoV-2 infection.”
The organization also claims to support initiatives in several countries to test antibodies against the new coronavirus in the population, to help understand the extent of the pandemic and the risk factors associated with the disease, but makes a reservation: “These studies will provide data about the percentage of people with detectable covid-19 antibodies, but most were not designed to determine if those people are immune to secondary infections. “
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