In November 2021 the UK Health Security Agency (2021) announced that those ‘aged 50 years and over, health and social care workers and younger people at risk are being offered a booster dose of coronavirus (COVID-19) vaccine’, arguing that since protection may wane over time, a booster ‘will help extend the protection you gained from your first two doses and give you longer term protection.’ In an Israeli study of participants who were 60 years old or more and had received two doses of the Pfizer–BioNTech BNT162b2 vaccine at least 5 months earlier, Bar-On et al (2021) reported that the ‘rates of confirmed COVID-19 and severe illness were substantially lower among those who received a booster (third) dose of the BNT162b2 vaccine.’
However, as Mahase (2021) observes, while the government’s vaccination advisory committee states that a booster programme is ‘precautionary’ to preserve ‘a high level of protection among vulnerable adults throughout winter’, she further explains that the Oxford-AstraZeneca vaccine developers Sarah Gilbert and Andrew Pollard are clear ‘that boosters were not needed because immunity was lasting well.’ In the context of 43% of the world’s population having received at least one dose of a COVID-19 vaccine, Gilbert and Pollard ‘have called for these vaccine doses to go towards vaccinating people around the world who are yet to have a single dose’ (Mahase, 2021).
To boost or not to boost; that is the question asked by Shekhar et al (2021) who remind us that antibody concentrations are used as surrogate biomarkers to measure vaccine efficacy and they acknowledge that a slow drop-off in antibody concentrations is to be expected. However, Shekhar et al (2021) also make clear that ‘there is insufficient data to suggest that this drop correlates with a decline in protection against the COVID-19 virus (correlate of protection) … [and that] … the correlate of protection and a protective threshold of the antibody levels for the COVID-19 vaccine is currently unknown.’
Perhaps a more important point raised by Shekhar et al (2021) is that of vaccine inequity on a global scale and its associated ethical implications, and they cite the World Health Organization’s director-general, who said it was ‘entirely unacceptable for countries that have already used most of the worldwide supply of vaccines to use even more of it.’ Further, ignoring the needs of ‘low- and lower-middle-income countries with higher population density and people living in closer approximation, the global efforts to control the COVID-19 pandemic may be futile’ (Shekhar et al, 2021).
This approach is expanded upon by Chagla and Pai (2021), who make the persuasive point that with 3.5 billion people worldwide who have yet to receive a first dose of the vaccine – only 2% of the African population have received a single dose – ‘[f]rom an equity perspective, there is a real risk of worsening the existing global inequity in vaccinations … [and] … Without widespread vaccination, it is impossible to protect any nation from the catastrophic consequences of the Delta variant, a variant that is highly transmissible and is associated with severe outcomes.’
It seems that while there is some evidence – although it is by no means unequivocally persuasive – to support the use of booster vaccinations from a purely scientific perspective, it is sometimes necessary to ply Occam’s razor, cut away unnecessary complexities and allow justice to prevail. This theme is again emphasised by Chagla and Pai (2021), who assert that in the context of globalisation, ‘it is unconscionable for the outcomes of COVID-19 to be determined simply by the country one resides in.’
But is it wrong to promote the concept of vaccine equity underpinned by the notion of natural justice when evidence-based medicine proponents argue that more prosperous nations should first consolidate their own population’s immunity? Not necessarily; and it’s worth considering Appleyard (1993), who contends not only that ‘[s]cientists need to be observed and criticised more than any other members of society’, but also that there is a necessity to make ‘them as morally and philosophically answerable as the rest of us.’ Appleyard (1993) also warns that assertions issued from the temple of science are prone to being flawed, often unconsciously, by the element of defensive propaganda.
Perhaps it’s not only our immune systems but our ethical sensibilities that need boosting.