BMJ Global Health (Aug 2022)

Epidemiological impact and cost-effectiveness analysis of COVID-19 vaccination in Kenya

  • Morris Ogero,
  • Edwine Barasa,
  • Ambrose Agweyu,
  • Matt J Keeling,
  • Philip Bejon,
  • Angela Kairu,
  • Wangari Ng'ang'a,
  • Mercy Mwangangi,
  • Stefan Flasche,
  • John Ojal,
  • Stacey Orangi,
  • J Anthony G Scott,
  • Patrick Amoth,
  • Samuel PC Brand,
  • Cameline Orlendo,
  • Rabia Aziza,
  • George M Warimwe,
  • Sophie Uyoga,
  • Edward Otieno,
  • Lynette I Ochola-Oyier,
  • Charles N Agoti,
  • Kadondi Kasera,
  • Rashid Aman,
  • Ifedayo MO Adetifa,
  • D James Nokes

DOI
https://doi.org/10.1136/bmjgh-2022-009430
Journal volume & issue
Vol. 7, no. 8

Abstract

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Background A few studies have assessed the epidemiological impact and the cost-effectiveness of COVID-19 vaccines in settings where most of the population had been exposed to SARS-CoV-2 infection.Methods We conducted a cost-effectiveness analysis of COVID-19 vaccine in Kenya from a societal perspective over a 1.5-year time frame. An age-structured transmission model assumed at least 80% of the population to have prior natural immunity when an immune escape variant was introduced. We examine the effect of slow (18 months) or rapid (6 months) vaccine roll-out with vaccine coverage of 30%, 50% or 70% of the adult (>18 years) population prioritising roll-out in those over 50-years (80% uptake in all scenarios). Cost data were obtained from primary analyses. We assumed vaccine procurement at US$7 per dose and vaccine delivery costs of US$3.90–US$6.11 per dose. The cost-effectiveness threshold was US$919.11.Findings Slow roll-out at 30% coverage largely targets those over 50 years and resulted in 54% fewer deaths (8132 (7914–8373)) than no vaccination and was cost saving (incremental cost-effectiveness ratio, ICER=US$−1343 (US$−1345 to US$−1341) per disability-adjusted life-year, DALY averted). Increasing coverage to 50% and 70%, further reduced deaths by 12% (810 (757–872) and 5% (282 (251–317) but was not cost-effective, using Kenya’s cost-effectiveness threshold (US$919.11). Rapid roll-out with 30% coverage averted 63% more deaths and was more cost-saving (ICER=US$−1607 (US$−1609 to US$−1604) per DALY averted) compared with slow roll-out at the same coverage level, but 50% and 70% coverage scenarios were not cost-effective.Interpretation With prior exposure partially protecting much of the Kenyan population, vaccination of young adults may no longer be cost-effective.