The use of antibody tests for SARS-COV-2 in the context of Digital Green Certificates

Technical report
Cite:
Citation Link

European Centre for Disease Prevention and Control. The use of antibody tests for SARS-COV-2 in the
context of Digital Green Certificates – 20 May 2021. ECDC: Stockholm; 2021.

Copy citation to clipboard

This brief technical note was developed at the request of the European Commission to inform the discussion on Digital Green Certificates to facilitate the safe and free movement of citizens within the EU during the COVID-19 pandemic.

Executive summary

Key messages

  • This brief technical note is to inform the discussion on using Digital Green Certificates to facilitate the safe and free movement of citizens within the EU during the COVID-19 pandemic.
  • At the moment, antibody tests are mostly used in research studies of the population rather than for individual diagnosis of COVID-19 cases.
  • A positive antibody test result can be proof of a past (including recent) infection, without providing any indication of the time of infection, and cannot exclude a current ongoing infection. Therefore, is not an absolute proof that a person is not infectious and/or protected against a new infection and cannot transmit the virus further.
  • Even if antibody tests provide some evidence of an immune response, it is not known if the antibody levels offer sufficient protection or how long such protection would last, i.e. how long this part of a Digital Green Certificate would be valid. It may well be that soon after a positive antibody test, the antibodies become undetectable.
  • It is still unknown whether the antibodies detected by commercial tests currently in use would prevent infection with newly emerging SARS-CoV-2 variants.
  • There are a variety of antibody tests and a comparison of their results is extremely difficult due to this variety and the lack of standardisation.
  • The tests that target the spike protein will be unable to distinguish between people who have been previously infected and those who have received at least one dose of the vaccine.