Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme Nairobi, Nairobi, Kenya
Institute of Healthcare Management, Strathmore University, Nairobi, Kenya.
BMJ Glob Health. 2022 Aug;7(8). doi: 10.1136/bmjgh-2022-009430.
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.
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$919.11.
Slow roll-out at 30% coverage largely targets those over 50 years and resulted in 54% fewer deaths (8132 (7914-8373)) than no vaccination and was cost saving (incremental cost-effectiveness ratio, ICER=US$-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.
With prior exposure partially protecting much of the Kenyan population, vaccination of young adults may no longer be cost-effective.
有一些研究评估了在大多数人已经接触过 SARS-CoV-2 感染的情况下，COVID-19 疫苗的流行病学影响和成本效益。
我们从社会角度对肯尼亚在 1.5 年时间框架内的 COVID-19 疫苗进行了成本效益分析。当出现免疫逃逸变体时，我们假设一个年龄结构传播模型中至少有 80%的人口具有先前的自然免疫力。我们研究了缓慢（18 个月）或快速（6 个月）疫苗推出的效果，疫苗覆盖 30%、50%或 70%的成年（>18 岁）人口，优先为 50 岁以上人群推出（所有情况下 80%的接种率）。成本数据来自主要分析。我们假设疫苗采购价格为每剂 7 美元，疫苗接种成本为每剂 3.90-6.11 美元。成本效益阈值为 919.11 美元。
以 30%的覆盖率缓慢推出主要针对 50 岁以上人群，与不接种疫苗相比，死亡人数减少了 54%（8132（7914-8373）），且具有成本效益（增量成本效益比，ICER=-1343 美元（-1345 美元至-1341 美元）/每残疾调整生命年，DALY 得到避免）。将覆盖率提高到 50%和 70%，进一步减少了 12%的死亡人数（810（757-872）和 5%（282（251-317），但不符合肯尼亚的成本效益阈值（919.11 美元）。以 30%的覆盖率快速推出可避免 63%的死亡人数，且更具成本效益（ICER=-1607 美元（-1609 美元至-1604 美元）/每 DALY 得到避免），与相同覆盖率水平的缓慢推出相比，但 50%和 70%的覆盖率方案没有成本效益。
由于先前的暴露部分保护了肯尼亚的大部分人口，因此为年轻人接种疫苗可能不再具有成本效益。
