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Wednesday, May 27, 2020

Explained: Are immunity passports, release certificates the way to go?

Immunity passports and release certificates are based on the idea that the natural immunity a person develops to any infection will protect them from contracting the disease again.

By: Explained Desk | New Delhi | Updated: May 10, 2020 1:56:59 pm
Explained: Are immunity passports and release certificates the way to go? People wearing face visors rest in a public garden in Ankara, Turkey, Friday, May 8, 2020. (AP Photo: Burhan Ozbilici)

Late last month, Chile announced that it would push for “release certificates” for those individuals who had recovered from Covid-19. The certificate would not prove immunity to the virus, but instead be issued to those who had finished a mandatory quarantine after testing positive for the disease.

Other countries such as the UK, Italy and Germany have also considered issuing “immunity passports” and “risk-free certificates” that would enable people to travel or return to work based on the assumption that having contracted the disease once, they would be immune to it for a considerable period of time.

On April 24, the World Health Organization (WHO) warned against using such certificates, since there was no evidence yet that a person infected with Covid-19 could not get the infection again. “There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection,” the global body said.

“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 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,” the WHO added.

However, in a subsequent post on Twitter, the WHO said it expected that “most people” infected with the disease would develop an antibody response that would provide “some level of protection”.

What is the idea behind immunity passports, release certificates?

Such certificates are based on the idea that the natural immunity a person develops to any infection will protect them from contracting the disease again. Once infected with a viral pathogen, the body’s innate immune response kicks in, which slows the spread of the virus and potentially helps not lead to any symptoms. This response is then followed by an “adaptive response”, wherein the body makes antibodies, which bind to the virus and help eliminate it. If this response is strong enough, it may even prevent re-infection from the same pathogen.

A study published on the pre-print server medRxiv on Tuesday found that a vast majority of Covid-19 patients produced antibodies “potentially providing immunity to reinfection”.

As per reports, the UK government has also bought over 3.5 million finger-prick antibody tests that can be conducted at home. These antibody tests work by drawing blood from a finger and using the sample to determine if one has coronavirus antibodies. Antibodies remain in the body for some time after the infection and hence are detectable by tests such as an antibody test. If the result is positive, it means the person has had coronavirus and therefore, may be immune to it as a result.

If considered, immunity passports will be issued to those who have recovered from Covid-19 and are deemed to be immune. Such people then may be able to get back to work and resume normal life.

What do we know about immunity from Covid-19?

At present, there is no evidence that contracting the infection once protects the person from getting re-infected. Further, even if immunity from Covid-19 is considered, the duration is not known. That is, will a person be immune for a few weeks, or a few months, or a couple of years? Due to the lack of evidence, the WHO has warned against using immunity passports and other such documents as a measure to be used for the next phase of the pandemic.

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What do critics say about measures such as immunity passports?

An article in The Lancet states using such documents poses “considerable scientific, practical, equitable, and legal challenges.” This is because it is not known if the presence of antibodies means that the person has developed immunity. Further, it is also not known what amount of antibodies will kick-off an immunity response and for how long.

“Individual-targeted policies predicated on antibody testing, such as immunity passports, are not only impractical given these current gaps in knowledge and technical limitations, but also pose considerable equitable and legal concerns, even if such limitations are rectified,” the article states. The equitable concerns include limiting the number of people who can participate in social, civic and economic activities, creating a “perverse incentive” for some individuals to seek out infection. Such measures may also be ripe for corruption and bias, which could be reflected in the administration of certification to discriminate against vulnerable groups.

Further, while a vaccine for Covid-19 may be months away, immunity passports are fundamentally different from vaccine certificates since the former incentivises infection and the latter incentivises getting vaccinated. Vaccine certificates may be an effective way to start lifting physical distancing measures, but this can also be implemented once a vaccine is ready.

Such measures may also face logistical problems as not enough test kits, such as at home antibody kits, are available to scale up the determination of immunity on a large scale. Some researchers are also skeptical about entirely relying on antibody tests to issue certificates.

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