The Astra Zeneca vaccine: weighing the benefits against the risks
Medical interventions involve risks and benefits — and an implicit or explicit weighing of benefits against the risks. This can be difficult to do, mostly because both can be highly individual. This is the case with the Astra Zeneca vaccine saga.
Let’s start with the risks, the clearer part of the equation. The AZ vaccine is probably associated with an increase in the rate of specific rate types of blood clots, as concluded by both the EMA in the EU and the MHRA in the UK. These side effects are however extremely rare: 86 with 18 fatal out of about 25 million vaccinations in EU and 79 with 19 fatal out of about 20 million vaccinations in the UK. Other vaccines haven’t been linked to any side effect of such seriousness.
The benefits are less clear. There is substantial evidence that the AZ vaccine prevents to some degree serious COVID infections, therefore drastically reducing the risk that a person may end up in the ICU, dead, or with lingering long-covid symptoms following an infection. For the society this is a clear benefit, although difficult to quantify precisely — the economic harm caused by measures aimed at slowing down the spread of the virus would be reduced as numerous industries would open again. Fewer people will die, and the pressure on the medical system would be reduced. Where things are less clear is what benefit lies for one person, or rather, how someone perceives this benefit.
First, some people have a reduced risk of getting infected, by having reduced contact with others. Some other people, for example the young and healthy, there is a very low chance of COVID developing into an illness that would require hospitalization. So far this is statistics. But beyond the hard numbers, there’s the perception. Some people don’t believe that the virus exists, or think this is ‘just a flu’. These people underestimate the risk they expose themselves to. For Superman, indeed, the vaccine wouldn’t have any benefit.
But there are other reasons to choose vaccination, beyond the scare of the infection. Vaccinated people protect others around them. Travel for vaccinated people would be made easier, as is already the case with certain countries. Peace of mind for not infecting others, who might not be as ‘young and healthy’ as we may like to think we are. Seeing loved ones, again.
So what now?
Limiting the use of the AZ vaccine will delay the vaccination process, but by how much it is unclear. This means that lockdown measures will last longer, and that people will be exposed to the virus for a longer time. This means not only more deaths, but also more pressure on the ICU and more long-covid cases.
It becomes clear here that, if someone has to be vaccinated, that is older people (less change of blood clots, more change of ICU admission with COVID). How about 30–39 then? Where we draw the line is, unfortunately, arbitrary.
Preferring other vaccines
Based on this calculation, most countries have limited the use of vaccines to elderly. What elderly means, and where does the balance of the risks turn towards more harm than benefit, is up to everyone’s interpretation.
In an ideal world, we would be able to offer The Pfizer or Moderna vaccine to everyone. There is however no capacity to vaccinate a whole population quickly using only these vaccines. The situation appears to be worse in poorer countries, where even the storage conditions of the Pfizer and Moderna vaccines may make vaccination prohibitive.
A delay in implementing vaccination strategies, because of the AstraZeneca fiasco, is now unavoidable. The communication around the topic has also likely lead to a mistrust around the AZ vaccine, which will result in further delays. Those delays will mean more deaths, ICU hospitalisations and long-covid cases.
In conclusion
The numbers often aren’t everything, but politics is the sport of covering the risks. A COVID death is the hand of destiny, but a blood clot is on the hands of the authorities. Scaremongering people into taking the vaccine is not the solution. The slow, difficult taks of educating future generations in scientific thinking, at least better than until now, will prove beneficial. If not for now, for the next pandemic.