GENEVA, April 25, 2020 (BSS/AFP) – The World Health Organization (WHO)
warned on Saturday that there is no evidence that people who test positive
for the new coronavirus are immunised and protected against re-infection.
The warning suggests that the issuance of “immune passports” may promote
the continued spread of the pandemic.
“There is currently no evidence that people who have recovered from
#COVID19 and have antibodies are protected from a second infection,” WHO said
in a statement.
“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.”
Some governments, wanting a gradual return to work and the resumption of
economic activity, have put forward the idea of issuing documents attesting
to the immunity of people on the basis of serological tests revealing the
presence of antibodies in the blood.
But the effectiveness of an immunisation thanks to antibodies has still
not been established and the available scientific data do not justify the
granting of an “immune passport” or a “certificate of absence of risk”, warns
the WHO.
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
WHO said.
“The use of such certificates may therefore increase the risks of
continued transmission.”
WHO also believes that the serological tests currently used “need
additional validation to determine their accuracy and reliability”.
In particular, the tests need to make it possible to distinguish the
immune response to the novel coronavirus from the antibodies produced during
an infection by another of the six known human coronaviruses, four of which
are widespread, causing 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 which interact with antibodies produced in response to
infection caused by SARS-CoV-2”, said WHO, empasising the importance of being
able to identify them.