By: Mohamed Afify
As we remain in the midst of the COVID-19 pandemic, vaccine hesitancy is still prevalent among a sizable portion of the population. While most people are fully vaccinated, some may be eligible for a booster shot in the future.
This week, the Centre for Disease Control and Prevention has approved booster shots for adults over the age of 65 and further expanded eligibility to adults aged 18-64 who would be considered high risk due to where they work. This group would include nurses and teachers.  The decision to expand eligibility was controversial as it was contrary to the advice of several panellists on the CDC’s vaccine advisory panel. These events pose several questions pertaining to the vaccine rollout and the future of combating COVID-19.
What is a booster shot?
It is essential to differentiate between a booster shot and a third dose as a part of initial vaccinations. Immunosuppressed people may need a third dose as a part of their primary vaccination schedule. This dose would be given approximately eight weeks from the second dose for those who qualify. 
The booster shot is given much later; however, a precise time estimate is difficult to determine as research is still ongoing. Figures range between six to eight months after the second dose. One study by the University of California San Diego found evidence that vaccine effectiveness could drop from 90% to 65% in months.  Since there is a decline in antibodies after the initial two doses, booster shots may be necessary to maintain vaccine effectiveness.
How effective and safe is the booster shot
There is controversy over the approval of booster shots because of the uncertainty surrounding this very question. Dr Phil Krause, an FDA vaccine regulator, stepped down over this issue, citing that the data has not been peer-reviewed, the models are complex, and scientists should ensure they give the correct results.  However, given that several studies have cited the diminished efficacy of the vaccines, some argue that it would be appropriate to work more proactively.
Pfizer published an observational study in Israel, which found that receiving a booster shot six months after the initial two doses restored protection to 95%. The Israeli health minister stated that the country’s healthcare system may have been overwhelmed if booster shots were not administered. Israeli health officials expected severe cases to average to 2000 by the end of the summer. This was mitigated through the proactive vaccine effort, which brought that figure down to 700, though there are still spikes of 10,000 cases per day.
This is the current rationale that health officials across the world are dealing with. On the one hand, there may still be gaps in the data regarding the effectiveness and safety of booster shots; however, in the context of new variants with higher rates of transmission, it begs the questions of how proactive should we be in implementing a booster shot policy
Should we be giving booster shots?
Though there is evidence indicating that booster shots may increase vaccine effectiveness from the initial drop that occurs a couple of months after initial vaccinations, some urge that this is the wrong approach. Increasing the vaccine effectiveness and thus, limiting transmission is already achieved through the initial vaccinations, and spread would be better addressed through vaccinating people who have no vaccine at all.
For example, if 50% of the U.S population who have already been fully vaccinated were to get a booster shot, disease spread would only decrease marginally compared to having 75% of the population vaccinated.  Though there are breakthrough cases in transmission among those who are vaccinated, research indicates that the unvaccinated are still the main drivers of transmission. 
WHO booster shot moratorium
In a WHO report, Dr. Ana-maria Heno-Resterpo asserted that the limited stock of vaccines would be better used if given to people who have not yet received a vaccine. Many world leaders have condemned this sort of vaccine hoarding by wealthier countries. The President of the Philippines stated, “They now talk of booster shots while developing countries consider half-doses just to get by. This is shocking beyond belief and must be condemned for what it is – a selfish act that can neither be justified rationally nor morally.”  While countries such as Canada have achieved a nearly 70% fully-vaccinated rate,  many countries such as Haiti and the Democratic Republic of Congo have less than 1%.
Having such low vaccination rates in other countries presents a danger of new variants emerging and becoming widespread. The WHO announced a moratorium on booster shots (barring especially at-risk populations such as the elderly or those who are immunocompromised) until 2022. 
Moving forward, policymakers will have to balance domestic concerns regarding break-though cases, decreased vaccine efficacy and new variants while ensuring there is an equitable distribution of vaccines globally.
About MyOpenCourt: The Vaccine Mediator Tool
The Conflict Analytics Lab is creating a Vaccine Mediator tool that uses AI to aid clients who suffered adverse health effects due to a COVID-19 vaccine.
The Vaccine Mediator Tool is a no-fault compensation system where clients enter the relevant information to find whether they qualify for compensation. This would include anyone who suffered adverse health effects due to taking a booster shot.
This tool is in the final phase of testing and is expected to launch this fall.
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