Immunity passports could be the ticket to help reopen international borders
As the world’s biggest ever vaccination programme gets underway, so-called immunity passports are back in the headlines. A document verifying the holder’s status as Covid-free could allow international borders as well as concerts and other events to reopen.
So are immunity passports just the ticket, or do they remain a flight of fancy?
Medical clearance for travel is not a new thing. It was not long ago that a trip to many countries involved multiple jabs and a case full of pills, and WHO guidelines still mandate yellow fever inoculations for visitors to certain places. With countries including New Zealand, the United Kingdom, and the United States among those which have reacted to the more virulent strains of Covid-19 with additional pre-departure testing requirements, evidence of vaccination status is a simple next step to already existing procedures. But there are multiple issues to be resolved first.
The incredible efforts of the scientific community to reach a point where we now have multiple viable vaccines being administered in countries around the world is nothing short of heroic. But how will these vaccines be treated by different nations’ border security and health services? Recent data has shown the CoronoVac vaccine to have only a shade over 50% efficacy in Brazilian trials following initial reports of 78%.
Will Brazilians who have taken this vaccine be welcomed into countries where CoronoVac has not been approved for use?
The International Air Transport Association (IATA), which represents 290 airlines, or 82% of all air traffic, hopes to have a solution with its Travel Pass app. Although other players have entered the space, IATA has been able to build on its existing Timatic product, a travel document verification system used globally by airlines, airports, and travel agents to ensure compliance with passport, visa, tax, and custom regulations for destinations around the world.
The proposed Travel Pass app will have four interoperable modules which will allow countries to set their specific requirements. These requirements can be searched by passengers who can then use another module to find labs capable of providing the approved test or vaccine required for the passenger’s destination. These labs then use a third module to upload test and vaccination status for passengers, with the fourth module accessible by airline staff. As airline staff are the frontline in ensuring any testing and vaccination requirements are met, using an existing and standardised system with which they are familiar makes a lot of sense.
Of course, for immunity passports to be viable we still need to confirm two vital pieces of data: How long does immunity last? And, can a vaccinated traveller still asymptomatically spread the virus to others?
The first question is not one that can be immediately answered. When fighting off a virus through infection or after being vaccinated, our bodies create several types of cells; killer Tcells attack the virus, while helper Tcells stimulate B-cells to produce antibodies which lock onto the infection and mark it for attack. Some of these cells then turn into memory cells which remember what the virus looks like and how to fight it if it turns up again.
A simple way to think of this is as though the virus is a drunk nuisance at a pub. The patrons who notice the idiot are the Helper T-Cells. They notify the bar staff (the B-cells) who point out the problem customer to the security (the killer T-Cells) who kick them out. The bouncer on the door, the staff, or even the punters can all become memory cells, remember the face of the troublemaker and ensure they are dealt with appropriately next time.
Understanding how long immunity lasts is a matter of seeing what levels of antibodies, T-cells, B-cells, and memory cells are present at different times after taking the vaccine. Early research is promising and shows Tcells, which attack the virus, present six months after initial infection. But we still have to wait and see. Studies have shown memory cells from the Spanish flu were present 90 years after infection. We can but hope for similar results with Covid-19.
Regarding asymptomatic transmission – meaning an immune person can still carry the virus and pass it on to others – in this area too, early research is promising, though more is needed.
Still, with systems gearing up, and evidence mounting, there are encouraging signs that immunity passports may be one of the tools that help us to resume some sense of normality over the next six months.