Immunity Passport — Part 1: Exploration

What’s an immunity passport?

An immunity passport is a document that indicates whether a person is immune or not to a disease. In this context, the disease is COVID-19. It can take the form of a physical paper document, a mobile application, or a database in which your ID is tied to your immunity status. Here, we’ll use the term “immunity passport” because it’s the one that best captured our global imagination. You’ll hear people use “immunity cards”, “immunity certificates” and “risk-free certificates” to refer to the same idea.

Searches for “immunity passport” vs “immunity certificate” vs “immunity card” (via Google Trend)

Why do some people think we need an immunity passport?

Many have argued that confining people who are immune to COVID-19 serves no purpose, and only hurts the economy. They believe that immune people should go back to their normal life and participate in the economy. They shouldn’t be confined, they shouldn’t have to wear masks, and they shouldn’t be forced to respect social distancing. They should be allowed to travel. They should be given priority when applying for high-risk (COVID-19 wise) jobs such as interacting with confirmed cases or taking care of the elderly.

Chile’s “Carnet Covid”

Why are some people opposed to immunity passports?

Many scientists believe that it’s too early to issue immunity passports. They claim that we don’t know enough about the virus to determine whether (and how long) people who have recovered are protected against re-infection. The World Health Organization recently published their concerns about immunity passports.

There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.

— World Health Organization

Others believe that even if we had a reliable way to determine whether someone is immune or not to COVID-19, we still shouldn’t issue immunity passports. They fear that it would introduce a new class division in society: the immunes and the non-immunes. If anything, it might make things worse, as people would be encouraged to seek out the virus in ways reminiscent of pox parties.

Where would immunity passports be required?

Immunity passports might be required in scenarios where a person would interact with infected people (e.g., doing triage in an emergency room) or interact with vulnerable people (e.g., volunteering in a nursing home). They might also be required when using public transportation, going to the gym, donating blood, preparing food, or traveling between different cities/regions.

Requirements to donate plasma for coronavirus patients (via American Red Cross)

How would immunity be determined?

We still don’t know enough about COVID-19 to tell if immunity is possible and how long it could last. Studies on SARS-CoV, the closely related virus responsible for 2003’s SARS outbreak, determined that its antibodies offer protection for roughly two to three years. More time and research will be necessary to know whether we can expect the same from SARS-COV-2.

  • A person has symptoms, tests positive for COVID-19 (typically via RT-PCR), and then recovers.
  • A person has no symptoms and tests positive for SARS-CoV-2 antibodies (typically via IgM/IgG immunoassay).
  • A person receives a COVID-19 vaccine.

Don’t immunity passports already exist?

The idea of an immunity passport isn’t new. In fact, they already exist and we still use them every day. The best example is the International Certificate of Vaccination or Prophylaxis (ICVP), which is issued by the World Health Organization and is mostly used as a proof of yellow fever vaccination (which is mandatory to enter many countries).

International Certificate of Vaccination or Prophylaxis (via CDC)
Screenshots from Travel Vaccines Enter the Digital Age: Creating a Virtual Immunization Record

What about immunity passports for COVID-19?

While the ICPV could be used as proof of COVID-19 vaccination, and maybe even allow for antibody test results to serve as proof of immunity, many teams around the globe have been working on immunity passports dedicated to COVID-19. Interestingly, they’re almost exclusively digital. I hope you don’t mind QR codes.

CoronaPass by Bizagi
Carnet Covid (Chile)
COVID-19 Antibody Test Certification by OpenUniversity’s Knowledge Media Institute (UK)
Immuno Lynk by MIT (USA)
CANImmunize (Canada)
CERTIS by SICPA (France)
Socios Pass by Socios
Sacyl Conecta (Spain)
Verifiable Credentials’ roles and information flow (via Verifiable Credentials)

Are there alternatives to immunity passports?

China has been conducting what is by far the largest and most successful contact-tracing experiment for months already. Their solution, known as the AliPay Health Code, has been deployed in over 200 cities in China. If you want to move around, you’ll need to install the app. It’s mandatory.

AliPay Health Code (via The New York Times)

What’s with all the apps and QR codes? Can’t we just use the International Certificate of Vaccination and Prophylaxis?

While the ICVP perfectly served its purpose since its introduction in 2005, it’s not clear that it’s the best solution in the context of a global pandemic in 2020.

  • Physicality: It’s one more thing to carry. It can’t be issued or verified online. It can be forgotten or lost. It can’t be backed-up.
  • Size: It’s meant to be carried in a passport. It’s too big to fit inside a wallet.
  • Durability: It’s made from cardboard. It’s not durable enough to be used daily. It can easily get damaged if wet.
  • Authenticity: It uses signatures and stamps, which motivated individuals could fake.
  • Verification: It’s handwritten, which makes it slow to read and verify.
  • Mutability: Its content can’t be updated or revoked (as we learn more about COVID-19 immunity).
  • It already exists.
  • It’s simple (no QR codes, no cryptography, no public key registry).
  • It’s proven and well understood (at least at some international borders).
  • It’s flexible (you can repurpose the boxes for other things like antibody testing, you can write notes).
  • It’s accessible (people don’t need to use or understand technology).
  • It’s reliable (you don’t need to worry about bugs, connectivity, or battery).
  • It’s private (doesn’t require a database with personal information).
Immunity bracelet from Contagion (2011)

What makes digital immunity passports more secure than physical immunity passports?

To verify the authenticity of a physical document, you usually look for physical characteristics that would be difficult to counterfeit. For example, banknotes often have security features such as seals, microprinting, raised printing, etc. On an ICVP, the only security features are a handwritten signature (which you usually can’t verify) and a stamp (which is hard but not impossible to fake).

JSON Web Token with an HMAC-SHA256 digital signature (in blue)
A QR code that contains the text “Hello world!”

When can I expect to receive my immunity passport?

While Chile is expected to issue immunity passports in the coming days, you might never actually receive yours. Technical and ethical challenges are slowing down their release, and some have predicted they would never see the light of day. If we’ve learned anything about them, it’s that they’re controversial and hard to get right.

What’s next?

In my next post, I will propose a technical specification for a digital immunity passport.

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