Public Health Emergency of International Concern (PHEIC)
We certainly recognize the velocity of global developments in the COVID-19 pandemic. While we have concentrated the most current key reports just below, COVID-19 announcements, analysis and commentary will be found throughout this issue, in all sections.
Beyond the considerable continuing coverage in the global general media, the WHO’s authoritative guidance is available here:
:: Daily WHO situation reports here: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports
:: WHO Coronavirus disease (COVID-2019) daily press briefings here: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/media-resources/press-briefings
Situation report – 96 [WHO]
Novel Coronavirus (COVID-19)
25 April 2020
SITUATION IN NUMBERS
2 719 897 confirmed (93 716)
187 705 deaths (5767)
1 314 666 confirmed (30 450)
119 463 deaths (2940)
Region of the Americas
1 047 508 confirmed (52 138)
53 103 deaths (2520)
Eastern Mediterranean Region
154 971 confirmed (5676)
6750 deaths (142)
Western Pacific Region
141 470 confirmed (1688)
5906 deaths (37)
South-East Asia Region
41 073 confirmed (2501)
1658 deaths (104)
19 497 confirmed (1263)
812 deaths (24)
WHO RISK ASSESSMENT
Global Level – Very High
:: WHO, together with heads of state, global health leaders, private sector partners and other stakeholders launched the Access To COVID-19 Tools (ACT) Accelerator, a global collaboration to accelerate the development, production and equitable access to new COVID-19 diagnostics, therapeutics and vaccines. More information including the WHO Director General’s opening remarks, full list of participants, and the group’s statement, are available.
:: Although some governments have suggested that the detection of antibodies to SARS-CoV-2, the virus that causes COVID-19, could serve as the basis for an “immunity passport” or “risk-free certificate”, there is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection. More information is available here.
:: WHO has seen a dramatic increase in the number of cyber-attacks directed at its staff, and email scams targeting the public. WHO asks the public to remain vigilant against fraudulent emails and recommends using reliable sources to obtain factual information about COVID-19 and other health issues. More information is available here.
“Immunity passports” in the context of COVID-19
WHO Scientific Briefs
24 April 2020
WHO has published guidance on adjusting public health and social measures for the next phase of the COVID-19 response.1 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.2-17 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,4 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.21 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.
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.
Citations/References at title link above