A difficult dilemma

This week, the WHO called for an urgent moratorium on COVID-19 booster shots until at least the end of September to enable nations worldwide to innoculate a minimum of 10 per cent of their population. The appeal by WHO chief Tedros Adhanom Ghebreyesus comes at a time when vaccine inequity worldwide has reached grotesque proportions. The latest data shows that while a significant proportion of high-income countries have fully inoculated over half their population, many lower-income countries are yet to go past even one per cent of their total population. It is in this context that the WHO wants wealthier countries with higher vaccination rates to hold back on giving out the first booster doses to those who are already vaccinated. Beyond the obvious issue of vaccine inequity, there is also the issue of figuring out just when booster shots are necessary. There is plenty of disagreement on this. The idea is that the immunity from a vaccine drops off at some point with some people having a drop of antibodies sooner than others. COVID variants also complicate the issue as newer, more infectious variants reduce the effectiveness of vaccines. But in general, full inoculation is likely to keep the risk of serious disease for quite some time even if it loses its effectiveness against preventing infection over time. Trial data for mRNA vaccines shows that the efficacy percentage for protection against serious illness remains over 90 per cent after six months. There is also the problem of deciding what exact threshold to use to determine if immunity has waned to a point that boosters are required. Pfizer CEO Albert Bourla stated in April this year that people will likely need booster shots every six to 12 months. More recently, Moderna stated that it expects people to start receiving booster shots to keep strong protection against variants as early as fall 2021. But by and large, the scientific consensus is that the argument for booster shots is weak at this point. There is a simple reason for this. It makes little sense to use resources to patch up a small drop in efficacy over vaccinating someone who is yet to receive even a single dose. The main goal should continue to be getting the shots into the arms of as many people as possible worldwide so that the virus has a limited pool of hosts to thrive, spread and evolve inside. That said, there are further complications to the question of boosters. As the Delta wave is making apparent worldwide, some countries that have relied more significantly on inactivated virus vaccines such as those that received Chinese Sinopharm vaccines have to go for boosters earlier as the effectiveness of the protection starts waning much sooner. This is why the UAE is offering Pfizer-BioNTech booster shots to anyone who was inoculated with Sinopharm vaccines. Naturally, this will not be the case for every country and there is thus, little evidence to suggest a general move towards boosters at this stage of the pandemic. But some countries will still err on the side of caution regardless. Since the WHO request for a moratorium on booster shots, Germany, the US and France have openly rebuffed WHO advice. The US, for instance, stated that it had no reason to give in to the 'false choice' of choosing between giving boosters to its population and doing its part to supply vaccines worldwide as it feels it could do both. For now, all three countries seem to aim for a targeted booster campaign that will cover those who are more vulnerable like the elderly or the immunocompromised. Regardless, it is hard to say that the current state of affairs in vaccine distribution will allow the world to reach inoculation targets set by the WHO. The organisation has stated that it wants every country to have 10 per cent of its population inoculated by the end of September, 40 per cent by the end of this year and 70 per cent by the middle of 2022.