Price, Priorities, Pace: Three Factors that Drive Cost-Effectiveness of COVID-19 Vaccination Strategies in Kenya, Nigeria, and Ethiopia

On behalf of all collaborators on COVID-19 Vaccine HTA in African countries project including (but not limited to) Stacey Orangi, Edwine Barasa, John Ojal, Benjamin Uzochukwu, Chinyere Okeke, Firmaye Bogale, Sabit Ababor, Yoseph Gebreyohannes, Justice Nonvignon, Elias Asfaw, Anna Vassall, Mark Jit, Francis Ruiz, Eleanor Bergen, Yang Liu, Sergio Torres-Rueda, Carl Pearson, Simon Procter, Tom Drake, Anthony McDonnell, Lydia Regan, Peter Baker, Javier Guzman.

In the past two years, we have all learned that the end of a COVID-19 wave is the end of a chapter, not the end of the story. Ongoing COVID transmission means the risk of new variants of pandemic potential is ever present and vaccination remains our best defence. The primary near-term challenges for vaccinating Africa are delivery difficulties and vaccine hesitancy. In the medium to longer term, as new and reformulated vaccines emerge and booster doses are required, ensuring reliable supply mechanisms will be essential. It is therefore critical to quantify the benefits of and reiterate the case for COVID-19 vaccination, and to learn from the recent past and identify the best strategies to achieve the greatest health impact given current constraints.    

This week, a collaboration between KEMRI-Wellcome Trust, the University of Nigeria, the Ethiopian Public Health Institute (EPHI), the London School of Hygiene & Tropical Medicine, the University of Warwick, the Africa Centres for Disease Control and Prevention (Africa CDC), and the Center for Global Development, is presenting a series of health technology assessments (HTA) on COVID vaccines in Kenya, Nigeria, and Ethiopia at the 13th Annual Conference of the International Society for Priorities in Health. The key take-aways of this work are:

• Vaccines can substantially reduce severe cases and save lives in Africa. In Kenya, vaccine coverage of 30 percent (that prioritizes people over the age 50) could have decreased infections by 10 percent and decreased deaths by 54 percent, compared to no vaccine over 1.5 years. In Nigeria, vaccinating just 25 percent of the population could have averted up to 430,000 disability-adjusted life years (DALYs) over five years.
• Vaccines have the potential to be highly cost-effective for African countries. Vaccines can even help African health systems to save money by reducing the cost of treating patients, but this depends on three critical factors:
  1. Vaccine price drives cost-effectiveness; for example, in Ethiopia and Nigeria vaccines would not have been cost-effective from a domestic payer perspective if the cost exceeded around $10 and $6 a dose, respectively.
  2. Getting vaccines to the right people matters. For example, in Kenya, targeting 30 percent of the population at greater risk of severe outcomes (those older than 50) would be cost-saving from the societal perspective, and cost-effective from the health system perspective, but expanding this to 50 percent of the population would not be good value for money compared to alternative health services (in part this reflects high levels of natural immunity due to prior exposure).
  3. Getting vaccines to people quickly is critical, but the delivery strategy (e.g., vaccination campaign vs through health facilities) appears to be less a driver of cost-effectiveness than other factors, such as vaccine price.

What’s the context?

As of 20 April 2022, over 251,000 deaths from COVID have been reported in the African region, with a total of over 11.2 million cases of COVID-19, though some studies point to the true impact being far greater. A meta-analysis of seroprevalence surveys reported that up to 65 percent of Africa had prior exposure to COVID-19 as of December 2021. In 2021, vaccines offered a ray of hope, but early supplies were purchased by richer countries, leaving a scarcity of supply for low-income countries. Supply and delivery of COVID vaccines in African countries has improved, but to date, just 15 percent of the adult population has been fully vaccinated.

Against this backdrop, many countries are considering purchasing and distributing vaccines with domestic public resources, yet every shilling, birr, or naira spent on COVID-19 vaccines is one not spent on other essential health services. Therefore, investing in COVID vaccines needs to be carefully appraised, considering evidence on both costs and impact, and taking into account the broad health needs of the population and budget constraints.

What we did

The aim of this programme was to provide evidence on the impact and costs of COVID-19 vaccine policy choices that is relevant to policymakers in Kenya, Nigeria, and Ethiopia in the context of local decision processes. Policy questions included:

• Which COVID-19 vaccines should be bought and at what price?
• How should vaccines be delivered?
• What is the cost and cost-effectiveness of targeted vaccination of specific groups?

The research teams undertook a series of economic and epidemiological analyses working closely with policymakers in three countries: Kenya, Nigeria, and Ethiopia. In Nigeria and Ethiopia, we used a Health Technology Assessment (HTA) framework to systematically evaluate the properties, effects, and impacts of vaccines as a health intervention. This framework is especially useful for assessing the impact of health interventions within the wider context of a country and considers a range of evidence. In Kenya, the research focused on the economic evaluation component; the team plans to develop it into a wider HTA.

All analyses used SARS-CoV-2 age-structured dynamic transmission models with inputs including costs of vaccination, cost of illness, contact patterns and outputs from cases, hospitalisations, and deaths from COVID-19. A range of vaccine types were assessed, including viral vector vaccines (similar to AstraZeneca and Johnson & Johnson) and mRNA-based vaccines (similar to Pfizer-BioNTech and Moderna). The analyses also considered various age-group rollout strategies and vaccine delivery modalities, as well as differences in the pace of vaccine roll out. In Kenya, the analyses assumed that 80 percent of the population had natural immunity due to prior infection.

The outputs included costs, incremental cost-effectiveness ratios (ICERs), and disability adjusted life years (DALYs) averted, a measure that captures years of life lost due to premature mortality, adjusted by time spent with disability or disease. These outputs allowed us to consider the comparative cost-effectiveness of alternative actions.

The COVID-19 pandemic is fast moving, with new variants and vaccine supply fluctuations that are hard to predict. This posed a challenge in our research. The analysis reflects the situation in 2021 and, for Ethiopia and Nigeria, did not consider the rapid emergence of the Omicron variant, though the Kenya analysis does. The analysis also does not account for future changes in the technologies available to prevent or manage the disease, or other changes that may affect the epidemiology and the impact on outcomes.

Finally, the analysis does not account for the impact of vaccines on reducing reservoirs of SARS-nCoV-2 transmission and therefore reducing the potential emergence of new strains. Broadly, studies took a health sector perspective and do not include benefits beyond health, including the macro-economic benefits of controlling COVID-19, though the Kenya study included productivity losses.

What we found

Vaccines reduce severe cases, save lives, and provide additional benefits

We know COVID-19 vaccination saves lives and these analyses highlight that. In Kenya, vaccine coverage of 30 percent could have reduced infections by 10 percent and reduced deaths by 54 percent, compared to no vaccine over 1.5 years. In Ethiopia, early effective vaccination with affordable viral vector vaccines similar to AstraZeneca and Johnson & Johnson could have averted between 180,000 and 440,000 disability adjusted life years (DALYs) over three years. Similarly, in Nigeria vaccinating just 25 percent of the population could have averted up to 430,000 DALYs over five years.

Which vaccine? Price matters

While many things contribute to the full cost of vaccinating populations, the price of the vaccine itself makes all the difference between cost-effective vaccination campaigns and costly inefficiencies. While mRNA vaccines perform slightly better than viral vector vaccines in preventing deaths and reducing transmission, they tend to be a lot more expensive. We found that viral vector vaccines, such as AstraZeneca and J&J, were generally a better choice in both Nigeria and Ethiopia, even considering the higher efficacy of mRNA vaccines. In Ethiopia viral vector vaccines would probably have saved the Ethiopian health system money by reducing the cost of looking after patients. The savings could have been as much as $200 million. In contrast a vaccine similar to Pfizer would have cost the health system between $150 million and $330 million. The HTAs in Nigeria and Ethiopia considered the maximum price for different vaccines that could be bought from the countries’ existing health sector budget. They found that at COVAX prices ($1.60 - $3.10 / dose), vaccination is good value for money, but at higher prices, ($6-10 / dose or more), vaccination would risk displacing more efficient health sector investments, when funded through national health sector budgets. In Kenya, vaccine prices of $3 and $10 led to a 32-103 percent decrease and a 36-77 percent increase in ICERs respectively compared to a base cost of $7 across the different vaccination scenarios.

Value for money means getting vaccines to the right people

It is intuitive that individuals facing greater risk of severe COVID outcomes have much greater capacity to benefit from vaccines. Our analyses confirm this also translates into improved cost-effectiveness. Across all studies, vaccinating older people and those most at risk of severe disease provides better value for money. In fact, in Kenya, it was found that achieving a relatively modest population coverage of 30 percent—preferentially targeting those who are at high risk of severe disease and death (modelled as the over 50s here)—is cost-saving while expanding to 50 percent of the population was not found to be value for money compared to the 30 percent coverage scenario. In Nigeria the analysis broadly confirms the Nigerian government’s age group prioritisation strategy, which focused on people over 50 years-old during Phase 2 of the roll-out, after initially focusing on health workers, supporting staff, frontline workers, and first responders in Phase 1. The decreasing marginal effectiveness of an age-based rollout strategy is compounded by the fact that, over time, the prevalence of immunity due to previous infection increases.

While the models focus on age as a COVID risk factor, there are a range of other factors which elevate risk, including other health conditions as well as occupational risks including health workers. There could also be knock-on effects of COVID illness. Surges of illness and self-isolation among health care workers can put huge pressures on healthcare systems and can result in a sudden drop in the capacity to deliver essential services. At the end of 2021 less than one in ten healthcare workers in Africa were fully vaccinated.

Getting vaccines to people quickly is key

Administering vaccines to a population quickly depends both on when vaccination rollout can begin and on a country’s ability to deliver a fast rollout once vaccines are available. Catching outbreaks early and vaccinating quickly make all the difference to reducing exponential growth and limiting public health impact. Faster rollout, of course, requires reliable vaccine supply and effective mechanisms to deliver, which is still challenging in many African countries. Both the Nigeria and Ethiopia studies found that earlier supply was a more important driver of getting vaccines to people quickly than the delivery strategy (such as dedicated campaigns or distribution through health facilities). Similarly in Kenya, a faster vaccine rollout used resources more efficiently.

Conclusion

African countries are moving towards managing COVID-19 as an endemic disease, while at the same time remaining prepared for potential surges caused by new variants. Notwithstanding the changing nature of the pandemic, the evidence presented here on the relative costs and impacts of COVID-19 vaccination can help health leaders to:

• Buy and deliver vaccines to protect people from the worst consequences COVID-19
• Choose vaccines carefully when procuring and negotiate low prices
• Ensure vaccines are prioritised to those with the greatest capacity to benefit
• Establish mechanisms to secure vaccine supply for when it’s needed

Ideally, bespoke analysis will be available to decision makers in times of need. In absence of this, these broad lessons, now grounded in evidence, can provide guidance.