Since the beginning of 2020, the tragic reality of the pandemic has unfolded, killing millions, disrupting social interactions, destabilizing economies and dragging the world into uncertainty. Between 4.3 and 11.6 million people have died from COVID-19.
In the midst of this sadness that only intensifies, vaccines have brought hope. Its development is a triumph of science; the production and application of 4.4 billion doses coming from a handful of developers is an amazing and lucky milestone. In the United Kingdom alone, more than 88 million doses, which are estimated to have saved more than 84,000 lives. Globally, vaccines are estimated to have saved millions of lives.
So why is there still so much suffering around the world? Every week thousands of people die from COVID-19. Hospitals are overwhelmed and many countries they beg for the arrival of vaccines because they have practically none. We are in this situation for a simple reason: the available doses are not being delivered in the first place to those who are most at risk of becoming seriously ill or, worse, dying.
The vast majority of people who will die of COVID-19 this year could have been saved if we had done things right. Vaccinating at-risk populations also serves our own interests. It could reduce the risk of new variants emerging, and it will ease the burden on our health systems, encourage tourism, resuscitate the global economy, and give greater international authority to politicians prepared to assume such moral leadership.
Although it is estimated that there will be a million more deaths from COVID-19 in December, and that a large part of the world population lives in fear of not being able to access the vaccine, Western governments are considering giving a third booster dose to those citizens who have already received two.
At a time of great global need, we must make clear the scientific reasons behind the administration of third doses. And we must do it at the right time: even if some need a booster, this should not prevent high-priority groups from receiving the vaccine that could save their lives.
The goal of vaccination
The scientific and public health rationale for the need for large-scale booster doses is incomplete and unclear. People experience a drop in their antibody levels over time after getting vaccinated, and thanks to various studies we know that a booster dose would curb this decline. If very high antibody levels are better at preventing mild cases, this may be a good reason to give booster doses.
However, vaccination plans should not focus on sustaining high antibody levels to prevent mild or moderate infections. If we only look at the level of antibodies, we could end up vaccinating everyone repeatedly to try to deal with a virus that keeps mutating. The goal of vaccination is not to prevent mild or moderate cases, but rather hospitalization and death.
As the daily numbers of infections and deaths show, the virus that causes COVID-19 can infect those vaccinated. Cyclically infecting immunized individuals is a fundamental part of the biology of coronaviruses in humans. This in itself is not a cause for alarm. Vaccines give a high level of protection against severe cases.
Our immune systems have been trained by vaccines to respond to exposure to the virus, even if antibody levels have decreased. So instead of worrying about whether people will catch it, we should be concerned about whether the infection can lead to serious illness, a hospital admission, or worse.
The information we need and do not yet have is the level of antibodies or T cells required to keep people from getting seriously ill. If this could be measured and we also saw protection levels fall below that level, we would have a clear reason to administer booster doses. But we can’t measure it yet. And in the meantime, high-risk groups around the world are still waiting for their first doses.
All we can do is analyze the clinical data to see when, if any, is the time when booster doses are needed. The health authorities and the World Health Organization they follow this matter closely. In any case, it will be clear in the future and the steps that we must follow will be according to the information we have.
For now, we are in uncharted territory. We may need to give booster doses to increase and extend immunity, and we may not. There are precedents for both ways. Just one dose of the yellow fever vaccine offers lifelong protection. Instead, we need five or six doses of tetanus vaccine to be protected for life, and the flu shot is given every year. What place will COVID-19 vaccines occupy?
It is highly unlikely that the protection offered by the vaccine against severe disease will drop suddenly and that the ongoing pandemic will catastrophically begin again. Small mutations of the virus will occur to help it survive better among vaccinated populations. But those mutations don’t stop the immunity provided by the vaccine from working. Thanks to it, we continue to be protected from the possibility of becoming seriously ill due to the main variants that have arisen. For now.
It is not an “all or nothing”
This is not “all or nothing.” We need careful analysis of the available data to make sure there are no groups for whom reinforcements are needed now. On the other hand, for those who do not respond well to vaccines, more doses will not help, and access to new treatments is urgent.
This is a key moment for decision makers.
Large-scale booster vaccination in a rich country could be a signal to the rest of the world that boosters are needed everywhere. This will hog many doses and many people will die from not being able to get even one.
If millions of people are reinforced without a strong scientific argument, this moment will go down in history as the moment when political leaders decided to shirk their responsibility to the rest of humanity in the greatest crisis of our time.
Since the two doses have given us the luxury of having time on our side, we should not rush to reinforce the immunization of millions of people, while time is ticking for those who have not been inoculated. First, the first doses. It’s that easy.
Andrew Pollard is Director of the Oxford Vaccine Group at the University of Oxford. Seth Berkley is Executive Director of GAVI, the Alliance for Vaccines.
Translation of Julián Cnochaert