I remember my Yellow Card—not the one handed out by soccer referees, but the one tucked in my passport when I first traveled to Ecuador in 1981 with Amigos de las Américas to work on a tuberculosis surveillance project.
The Yellow Card was really the “International Certificate of Vaccination or Prophylaxis”, and was on hearty yellow paper stock. It had a stamp in place to show that I had been vaccinated against Yellow Fever, a viral infection transmitted by mosquitoes and quite lethal. It was required by the government of Ecuador for all entrants, unless a physician certified that the vaccine could not be administered for medical reasons, or if I had perchance recovered from illness. There were also lines to enter other immunizations that may have been administered, as well as information about potential malaria prophylaxis. This document was tucked into my passport, and perused by the immigration officer at the Quito airport. I don’t recall if Smallpox was also on that card, but I also bear a scar showing I’ve been immunized against Smallpox. Additionally, Smallpox had been declared eradicated in 1980 by the World Health Organization.
Of course, the document couldn’t guarantee that I was immune, and I suppose it could have easily been forged (it wasn’t), but the intent was that only people with some level of protection, assuming medically able to be immunized, were allowed passage into the country. Once past the border, no one cared about it.
Even before Yellow Fever immunization, there were also documentation cards for Smallpox, another deadly viral disease. However, Smallpox was declared eradicated
Now, there is chatter about a new “Vaccine Passport”—a document, either paper or digital, certifying that the bearer has been immunized against SARS-CoV-2, the virus that causes COVID-19 disease. The state of New York has one. But what would be the benefit of such a document? How would it be used? What does it even mean?
As the days, weeks, and months roll on from the time of the first clinical trials of vaccine, we learn more and more about how effective vaccination is against SARS-CoV-2. And the answer is: really, really good. For those who have been immunized, the clinical trials show anywhere from 60 to 95% effectiveness against any disease, and just about 100% effectiveness against serious illness or death. This is about as good as it gets for most vaccines.
Of course clinical trials and “real world conditions” are not the same thing. Clinical trials may exclude people with some underlying conditions that blunt immune response to vaccination. The SARS-CoV-2 virus shows ability to shift and develop some resistance to vaccination or immunity from previous infection. So results of trials cannot be completely extrapolated to the general public. Nevertheless, we are seeing real benefits of the vaccine, especially in the most vulnerable population.
So what is the purpose of a “vaccine passport”? What are the circumstances that should dictate use?
For now, the Centers for Disease Control and Prevention (CDC) have not given a lot of guidance on what vaccinated individuals can do. They can meet and dine with other vaccinated individuals, as well as select unvaccinated individuals. They do NOT have to quarantine after travel. That’s it! Getting together in medium size or large groups is NOT encouraged, even if vaccinated.
In part, this limited guidance reflects the limited knowledge of how effective these vaccines are against emerging Variants of Concern (VOCs). Several of these VOCs show reduced effectiveness of vaccination or previous infection to prevent infection with these VOCs.
Imagine a large gathering of people, even if all are immunized, where one or more has not responded well to immunization due to underlying health condition such as immune suppressing medications or immune system illness, and another has immune resistant variant—or failed to mount a response, and developed presymptomatic COVID-19. Transmission may occur. It likely will not be a “superspreader” event, as we see in unimmunized individuals, but the longer the exposure (say, on a cruise ship), the greater the likelihood of transmission. Reliance on any single technology to end transmission will lead to a false confidence of safety. This occurred last year when a government facility on Pennsylvania Avenue in Washington, DC relied solely on rapid testing to screen out disease, and did not follow other precautions such as masking and social distancing. Multiple superspreader events followed.
Some organizations, such as schools or hospitals, already require certification of immunization for various vaccine preventable illnesses, such as measles, mumps or Hepatitis B. Some hospitals even require annual influenza immunization. There is nothing new about requiring immunization in those settings. Undoubtedly, when safe and effective vaccines for SARS-CoV-2 are fully FDA approved, these will be added to the list of required immunizations. But none are now, and post marketing surveillance may reveal risks that could lead to some vaccines not getting that approval.
Even more dangerous, would be circumstances driving counterfeit vaccination and shot cards. If widespread expectations of COVID-19 “passports” come into effect, this will fuel a blackmarket trade in counterfeit vaccines for those who are desperate to get unavailable vaccine, and counterfeit shot cards for those who choose not to get vaccinated.
The best solution to the question of vaccine passports is to not need them at all. It is to crush the epidemic where you live through vaccination, continued social distancing, testing when sick or traveling, and getting to the end of the pandemic.
No doubt SARS-CoV-2 will continue to circulate, even after the pandemic is over, just as other viruses continue to circulate. But the threat level will be reduced to the point where certification for common activities is not needed.