There is currently “no evidence” that COVID-19 patients who have recovered and have antibodies “are protected from a second infection”, the World Health Organization said in a scientific brief released on April 24. The brief was in response to some countries suggesting the use of “immunity passports” or “risk-free certificates” to enable people to travel or return to work.

Countries including India, the UK, China, Italy, New Zealand, Poland and Singapore had declared a lockdown to contain COVID-19, which has now infected more than 2.8 million people worldwide and killed more than 203,000. As countries gradually start lifting lockdowns to bring back normalcy, some such as Germany and Chile are looking into giving immunity passports to recovered patients, Vox reported on April 25, 2020.

India has been under lockdown since March 25 and will remain so until May 3. Prime Minister Narendra Modi had suggested a staggered lifting of the lockdown. States such as Uttar Pradesh have announced that there will be no public gatherings until June 30.

Goa, which became the first state to report zero active COVID-19 cases, wants “people to come into the state of Goa carrying the COVID-negative certificate”, Vishwajit Rane, Goa’s health minister, told Govindraj Ethiraj in an interview. The certificate, unlike an immunity passport, may only indicate that a person is negative for COVID-19 and may not necessarily show if the person has recovered from an COVID-19 infection.

Goa does not want to allow anybody to enter the state without having thorough checks done, and was waiting for clarification from the Centre to know if the state can use antibody tests at the borders, Rane said, adding that the Centre has “said no, because ICMR does not believe that antibody test should be used at the borders”.

India had suspended the use of rapid antibody test kits imported from China for two days, on April 21, after complaints by state health authorities about the accuracy of the kits. Rapid antibody tests have been put on hold until further notice, India Today reported on April 25.

India has maintained that rapid antibody tests are to be used as a surveillance tool, and the “gold standard” for detection of COVID-19 postives is the RT-PCR test.

Like Goa, the Kerala government had said on April 22 that it would “allow only those people [expats] who carry the COVID negative certificate (to travel to the state)”. Back in March 2020, the bureau of immigation, under the home ministry, had issued an advisory that those travelling from or having visited Italy or Republic of Korea will need a certificate of having tested negative for COVID-19 from designated laboratories in these countries.

Following its scientific brief, on April 26, the WHO added that those infected with COVID-19 people “will develop an antibody response that will provide some level of protection”, but “the level of protection or how long it will last” is not known.

The brief had noted that the development of the body’s immunity is a multi-step process, which includes a “non-specific innate response” where the body tries to slow the virus or prevent it from causing symptoms, followed by an “adaptive response” where the body creates antibodies, called immunoglobulins, to bind to the virus.

The body also creates T-cells that remove cells infected with the virus. This combined 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”, and is measured by the presence of antibodies in blood.

But the tests that detect antibodies need to be validated for “accuracy and reliability”, the WHO’s brief had noted. Inaccuracies can lead to false positive and false negatives, and they also need to distinguish the other six known human coronaviruses.

Considering the lack of evidence about immunity from infection, use of such immunity passports or risk-free certificates may increase the risks of continued transmission, the world health body noted.

As of April 26, India has detected more than 26,000 COVID-19 cases, and 824 have died.

(Paliath is an analyst with IndiaSpend.)