As COVID-19 vaccines begin to emerge, policymakers around the world are feeling buoyant. Although governments will be the initial recipients of vaccines, their decisions on how to distribute these among their populations will be fundamental for the ultimate recipients: individuals. In view of the unprecedented global demand for vaccines, the COVAX Facility aims to support vaccine allocation to all countries, but especially low-and middle-income countries (LMICs), which would otherwise suffocate in the cold embrace of the global free-market. In the first phase, countries will receive vaccine doses proportional to the size of their population to cover up to 20 percent of citizens. With high-income countries also securing bilateral advanced purchasing agreements outside of COVAX, the pressing question of who exactly will make up this 20 percent, is especially pertinent for LMICs. This blog reflects on some of the tough decisions facing policymakers who must ensure that COVID-19 vaccines are first given to those who need them most.
Prioritising population groups
The single risk factor most overwhelmingly predictive of whether a person will suffer severe illness and death from COVID-19, is age. Observational data from the UK epidemic found that the risks of catching and dying from the virus varied 10,000-fold depending on age. This is perhaps why, in addition to its logistical simplicity, the UK Joint Committee on Vaccination and Immunization (JCVI) have recommended that in addition to healthcare workers, vaccines be prioritised on the basis of age, starting with those 80 and above and working down.
LMICs may similarly target the elderly first, as well as healthcare workers. But with an average of only 7 percent being aged 65 years or older and the limited size of most LMIC health workforces, if the COVAX delivers on its 20 percent population promise, there will be vaccines spare. So who goes next?
One solution is to use lower age thresholds for the “elderly” than used in high-income countries, expanding the group eligible for first-round vaccine allocation. The WHO roadmap to guide country decisions on vaccine prioritisation recommends first prioritising older adults defined by age-based risk, specific to the country. This country-specific risk is important, since conditions that increase vulnerability to COVID-19 such as cardiovascular disease and diabetes occur at younger ages and are less well controlled in LMICs.
The Indian strategy reflects this with a relatively low age threshold for first-round vaccine allocation. Four priority groups have been identified, including healthcare workers, frontline workers (e.g. police and first responders), those over 50 years, and those less than 50 years with comorbidities. This is around 23 percent of the total population. Although the risk of death from COVID-19 is thought to be substantially lower in those aged 50-64 years compared to those aged 65 and above, in India almost half of all recorded deaths have been in those aged under 60 years. Similarly in Mexico, the probability of dying increased by 63 percent from an average year in the 45-64 year age group, compared with 33 percent in the over 65s.
Some may choose higher age thresholds for the elderly population, distributing the additional vaccines to others at a high risk of catching the virus, or getting seriously unwell with it. According to the WHO roadmap, after vaccinating the elderly as well as healthcare workers, stage two (i.e. 11-20 percent population coverage) involves vaccinating those with comorbidities and sociodemographic groups at a high risk of severe illness, and high-priority school staff. Second-round priority groups in high-income countries are more extensive. The US recommendations involve older people not previously covered, all with comorbidities, essential workers, school staff, the homeless and those in prisons or detention facilities. The EU Commission similarly stresses the importance of protecting essential workers and the socioeconomically disadvantaged.
The high-risk sociodemographic groups referred to in the WHO roadmap, will need to be more precisely defined according to the LMIC context. Two-thirds of the world population live on less than 10 $-int per day. Swathes of people reside in crowded informal settlements with poor hygiene and a lack of access to healthcare—with limited vaccines, who among these should be selected? Note that India’s strategy to get to 20 percent of its population does not include socially disadvantaged groups, but does include (the relatively easy to identify) frontline police and municipal workers.
It is emerging that many in LMICs have already been exposed to the virus, whether they knew it or not. A pre-print from Karnataka reported seroprevalence of COVID-19 antibodies at a whopping 46.7 percent of the population. This does vary across countries with estimates of 16 to 33 percent in Iran and 25 percent in Nigeria. Although many high-income countries also have high levels of seroprevalence—the proportion of the population with antibodies against COVID-19—particularly in urban areas, these are generally more commensurate with the numbers of cases identified through testing. The discrepancy between seroprevalence and recorded cases is important for vaccines because it represents a concealed population of recovered COVID-19 cases, who may unknowingly be immune already. Vaccine allocation is as much about prioritising, as it is deprioritising. There are still unanswered questions about whether those who have had COVID-19 are truly immune and how long for. If vaccination provides stronger or longer-lasting immunity compared to natural infection it may still be worth vaccinating this group, but since this is currently unknown, they should not be a priority. Identifying and deprioritising these individuals, likely to be numerous in the hardest-hit LMICs, will be challenging without the widespread use of antibody tests, and even these are not perfect.
Some have argued for the priority use of COVID-19 vaccines in “superspreaders” —those people who seem to spread the virus more than others. But bar some population groups, it is difficult to know who these people are in advance, and none of the trials are actually designed to answer the question of whether and by how much vaccines might interrupt transmission. If vaccinating healthcare workers prevents them from developing symptomatic illness (thereby maintaining their ability to work), but does not impact on their ability to transmit the virus, this could paradoxically exacerbate transmission in healthcare settings. With high-income countries greatly outbidding the rest of the world for personal protective equipment (PPE), nosocomial transmission of COVID-19 is already a real threat for LMICs. Outbreaks could overwhelm already poorly staffed critical care systems and further unsettle already disrupted health services. Of course, until more is known the arguments in favour of prioritising healthcare workers remain, but it is an apposite illustration of why understanding more about the role of emerging vaccines in interrupting transmission is so imperative.
Prioritisation as a process
It is not just about defining which groups should get priority for a vaccine. The process around prioritisation also matters. Most nations already have National Immunization Technical Advisory Groups (NITAGs) or equivalent bodies to select vaccines, determine target populations, establish delivery platforms and so on. Traditionally health-expert heavy, these groups can be strengthened with the inclusion of professionals from across government and industry. The appropriate implementation of COVID-19 vaccines is as much about the economy, logistics, society, and ethics as it is about health.
Concerns about the misuse of COVID-19 funds are abundant in many LMICs. In South Africa, a scathing report into the use of the Covid-19 relief fund has revealed overpricing and potential fraud. In Brazil, investigations into the mishandling of funds earmarked for the COVID-19 response have opened in all 27 Brazilian states. In Kenya, the Ethics and Anti-Corruption commission found public officials to be criminally culpable, with an identified “irregular expenditure” of 7.8 billion Kenyan shillings ($71.96 million).
Vaccines are not immune to misuse. Corruption will remain a threat if countries have disjointed systems with weak governance, poor transparency and a lack of accountability. Making the prioritisation process explicit and building in relevant safeguards will be as essential as coming up with priority groups in the first place.
Ultimately, despite COVAX, there will need to be some consideration of the costs and benefits of vaccines; that vary across countries. Even in a public health crisis, value-based pricing is important. Having a clear, explicit, and expert-led process in place outlining which vaccines will be allocated, to whom, when, where, and how, can help countries in determining “value,” that can be measured through cost-effectiveness (e.g. cost-per-QALY). In turn, understanding how valuable vaccines are as currently allocated could help to refine the prioritisation process and maximize their value.
Although there are common principles, it is up to governments how exactly to delineate and identify the high-risk populations to be prioritised for novel COVID-19 vaccines. Objectives will have to be tailored to the local epidemiology (including age-specific risk), the availability of vaccines over time, and the size of target population groups. Countries must leverage existing systems and population registers to systematically identify priority individuals, as part of a transparent process that is able to record, monitor and recall those vaccinated. This will be no small feat. But the recent achievements of global vaccination programmes provide more than a little hope.