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WHO Flips on Antibodies Aiding COVID-19 Immunity

Treyfish

Treyfish

Moderator
"Immunity passports" in the context of COVID-19

Scientific Brief

24 April 2020
WHO has published guidance on adjusting public health and social measures for the next phase of the COVID-19 response.[SUP]1[/SUP] Some governments have suggested that the detection of antibodies to the SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an “immunity passport” or “risk-free certificate” that would enable individuals to travel or to return to work assuming that they are protected against re-infection.
There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.

The measurement of antibodies specific to COVID-19

The development of immunity to a pathogen through natural infection is a multi-step process that typically takes place over 1-2 weeks. The body responds to a viral infection immediately with a non-specific innate response in which macrophages, neutrophils, and dendritic cells slow the progress of virus and may even prevent it from causing symptoms. This non-specific response is followed by an adaptive response where the body makes antibodies that specifically bind to the virus. These antibodies are proteins called immunoglobulins. The body also makes T-cells that recognize and eliminate other cells infected with the virus. This is called cellular immunity. This combined adaptive response may clear the virus from the body, and if the response is strong enough, may prevent progression to severe illness or re-infection by the same virus. This process is often measured by the presence of antibodies in blood.

WHO continues to review the evidence on antibody responses to SARS-CoV-2 infection.[SUP]2-17[/SUP] Most of these studies show that people who have recovered from infection have antibodies to the virus. However, some of these people have very low levels of neutralizing antibodies in their blood,[SUP]4[/SUP] suggesting that cellular immunity may also be critical for recovery. As of 24 April 2020, no study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans.

Laboratory tests that detect antibodies to SARS-CoV-2 in people, including rapid immunodiagnostic tests, need further validation to determine their accuracy and reliability. Inaccurate immunodiagnostic tests may falsely categorize people in two ways. The first is that they may falsely label people who have been infected as negative, and the second is that people who have not been infected are falsely labelled as positive. Both errors have serious consequences and will affect control efforts.

These tests also need to accurately distinguish between past infections from SARS-CoV-2 and those caused by the known set of six human coronaviruses. Four of these viruses cause the common cold and circulate widely. The remaining two are the viruses that cause Middle East Respiratory Syndrome and Severe Acute Respiratory Syndrome. People infected by any one of these viruses may produce antibodies that cross-react with antibodies produced in response to infection with SARS-CoV-2.

Many countries are now testing for SARS-CoV-2 antibodies at the population level or in specific groups, such as health workers, close contacts of known cases, or within households.[SUP]21[/SUP] WHO supports these studies, as they are critical for understanding the extent of – and risk factors associated with – infection. These studies will provide data on the percentage of people with detectable COVID-19 antibodies, but most are not designed to determine whether those people are immune to secondary infections.

Other considerations

At this point in the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an “immunity passport” or “risk-free certificate.” People who assume that they are immune to a second infection because they have received a positive test result may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission. As new evidence becomes available, WHO will update this scientific brief.



References
  1. Considerations in adjusting public health and social measures in the context of COVID-19. https://www.who.int/emergencies/dise...s-for-covid-19
  2. W?lfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients with COVID-2019. Nature 2020.
  3. To KK, Tsang OT, Leung WS, et al. Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study. Lancet Infect Dis. 2020 Mar 23. pii: S1473-3099(20)30196-1. doi: 10.1016/S1473-3099(20)30196-1.
  4. Wu F, Wang A, Liu M, et al. Neutralizing antibody responses to SARS-CoV-2 in a COVID-19 recovered patient cohort and their implications. medRxiv 2020: 2020.03.30.20047365.
  5. Ju B, Zhang Q, Ge X, et al. Potent human neutralizing antibodies elicited by SARS-CoV-2 infection. Biorxiv 2020: 2020.03.21.990770.
  6. Poh CM, Carissimo G, Wang B, et al. Potent neutralizing antibodies in the sera of convalescent COVID-19 patients are directed against conserved linear epitopes on the SARS-CoV-2 spike protein. Biorxiv 2020: 2020.03.30.015461.
  7. Zhang W, Du R, Li B, Zheng X, et al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerg Microbes Infect. 2020 Feb 17; 9(1):386-389. doi: 10.1080/22221751.2020.1729071.
  8. Grzelak L, Temmam L, Planchais C, et al. SARS-CoV-2 serological analysis of COVID-19 hospitalized patients, pauci-symptomatic individuals and blood donors. medRxiv 2020 (submitted 17 April 2020).
  9. Amanat F, Nguyen T, Chromikova V, et al. A serological assay to detect SARS-CoV-2 seroconversion in humans. medRxiv 2020: 2020.03.17.20037713.
  10. Okba NMA, M?ller MA, Li W, et al. Severe acute respiratory syndrome coronavirus 2−specific antibody responses in coronavirus disease 2019 patients. Emerg Infect Dis. 2020 doi: 10.3201/eid2607.200841
  11. Zhao J, Yuan Q, Wang H, et al. Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clin Infect Dis. 2020 doi: 10.1093/cid/ciaa344
  12. Guo L, Ren L, Yang S, et al. Profiling Early Humoral Response to Diagnose Novel Coronavirus Disease (COVID-19). Clin Infect Dis. 2020 Mar 21. doi: 10.1093/cid/ciaa310.
  13. Liu Y, Liu Y, Diao B, Ren Feifei, et al. Diagnostic indexes of a rapid IgG/IgM combined antibody test for SARS-CoV-2. medRxiv 2020; doi: 10.1101/2020.03.26.20044883
  14. Zhang P, Gao Q, Wang T, Ke Y, et al. Evaluation of recombinant nucleocapsid and spie protein serological diagnosis of novel coronavirus disease 2019 (COVID-19). medRxiv. 2020; doi: 10.1101/2020.03.17.20036954
  15. Pan Y, Li X, Yang G, Fan J, et al. Serological immunochromatographic approach in diagnosis with SARS-CoV-2 infected COVID-19 patients. medRxiv. 2020; doi: 10.1101/2020.03.13.20035428
  16. Li Z, Yi Y, Luo X, Xion N, et al. Development and clinical application of a rapid IgM-IgG combined antibody test for SARS-CoV-2 infection diagnosis. J Med Virol. 2020 Feb 27. doi: 10.1002/jmv.25727.
  17. Li R, Pei S, Chen B, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science 2020.
  18. Lou B, Li T, Zheng S, Su Y, Li Z, Liu W, et al. Serology characteristics of SARS-CoV-2 infection since the exposure and post symptoms onset. medRxiv 2020; doi: 10.1101/2020.03.23.20041707
  19. Lin D, Liu L, Zhang M, Hu Y, et al. Evaluation of serological tests in the diagnosis of 2019 novel coronavirus (SARS-CoV-2) infections during the COVID-19 outbreak. medRxiv 2020. doi: 10.1101/2020.03.27.20045153
  20. Liu W, Liu L, Kou G, Zheng Y, et al. Evaluation of nucleocapsid and spike protein-based ELISAs for detecting antibodies against SARS-CoV-2. medxriv [Internet]. 2020; Available from: https://doi.org/10.1101/2020.03.16.20035014 medRxiv preprint
  21. Unity Studies: Early Investigation Protocols https://www.who.int/emergencies/dise...investigations
WHO continues to monitor the situation closely for any changes that may affect this interim guidance. Should any factors change, WHO will issue an update. Otherwise, this scientific brief will expire 1 year after the date of publication.
 
Last edited:
...The statement comes days after Chile announced it would begin issuing immunity cards to travelers that effectively act as passports, allowing them to clear security at airports with a document that purportedly shows they have already recovered from the virus. Authorities and researchers in other countries — such as France and the United Kingdom — have expressed interest in similar ideas, while some in the U.S., such as Los Angeles Mayor Eric Garcetti, have mentioned it as one possible facet of a reopening strategy.

The concept for such a card is largely based on the premise that an individual can only contract the coronavirus once before developing the necessary antibodies to fight it off. That premise undergirds another common theory: the concept, known as herd immunity, that if enough of the population has been infected with the coronavirus — and is therefore immune — its transmission will slow and the risks of infection will diminish even for those who haven't caught it yet.

But these ideas depend to a large degree on the supposition that one cannot catch the coronavirus a second time — an idea that world health authorities said leaders should not count on right now. As of Friday, the WHO said, "No study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans."

What's more, data reported from the world's early COVID-19 hotspots, such as South Korea and China, have shown that a growing number of recovered patients appear to have suffered a relapse of the disease.

By mid-April, Korean health authorities said that scores of people — or just over 2% of the country's recovered patients — were in isolation again after testing positive a second time. And in Wuhan, China, data from several quarantine facilities in the city, which house patients for observation after their discharge from hospitals, show that about 5%-10% of patients pronounced "recovered" have tested positive again.

As yet, it remains unclear precisely why this is occurring — whether it is a sign of a second infection, a reactivation of the remaining virus in the body or the result of an inaccurate antibody test....:tiphat:https://www.npr.org/sections/coronav...mmune-who-says
 
....There have yet to be any studies that evaluate whether the presence of antibodies actually ensures immunity from a second infection, the global health agency added.

Germany, Italy and the U.K. have all floated the idea of using immunity passports in the next phase of their coronavirus response.

Anthony Fauci, a key member of the White House COVID-19 taskforce, previously noted the idea could have some merit “under certain circumstances” in the U.S., but added that antibody immunity has not yet been proven for COVID-19.

Meanwhile, officials in New York state have already begun antibody testing, an effort Gov. Andrew Cuomo says could potentially help set policy on when to reopen parts of the state.

Despite questions surrounding immunity, Chilean government officials say they are moving with plans to offer the world’s first immunity passports to citizens. The country says 4,600 people have recovered from the virus and will now be eligible to receive a physical or digital card exempting them from quarantine rules....:tiphat:https://www.ctvnews.ca/health/corona...down-1.4911729
 
WHO Flips on Antibodies Aiding COVID-19 Immunity
(AP)

By Eric Mack | Monday, 27 April 2020 10:16 PM

The World Health Organization is backing off its since-deleted tweet "there is no evidence" those who have recovered from the coronavirus have developed an immunity.

The WHO is now saying, via a Saturday tweet that has not been deleted:
"We expect that most people who are infected with #COVID19 will develop an antibody response that will provide some level of protection."​

The WHO was inclined to respond because their since-deleted tweet "caused concern & we would like to clarify."

The deleted tweet read, according to The Washington Times reported:
"There is currently no evidence that people who have recovered from #COVID19 and have antibodies are protected from a second infection."​

The tweet was intended to warn against nations "immunity passports" to those with COVID-19 antibodies.

"Some governments have suggested that the detec..:tiphat:https://www.newsmax.com/scitech/worl.../27/id/964941/
 
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