Qassim Suelen H, Chemaitelly Hiam, Ayoub Houssein H, Coyle Peter, Tang Patrick, Yassine Hadi M, Al Thani Asmaa A, Al-Khatib Hebah A, Hasan Mohammad R, Al-Kanaani Zaina, Al-Kuwari Einas, Jeremijenko Andrew, Kaleeckal Anvar Hassan, Latif Ali Nizar, Shaik Riyazuddin Mohammad, Abdul-Rahim Hanan F, Nasrallah Gheyath K, Al-Kuwari Mohamed Ghaith, Butt Adeel A, Al-Romaihi Hamad Eid, Al-Thani Mohamed H, Al-Khal Abdullatif, Bertollini Roberto, Abu-Raddad Laith J
Infectious Disease Epidemiology Group, Weill Cornell Medicine-Qatar, Cornell University, Doha, Qatar.
World Health Organization Collaborating Centre for Disease Epidemiology Analytics on HIV/AIDS, Sexually Transmitted Infections, and Viral Hepatitis, Weill Cornell Medicine-Qatar, Cornell University, Qatar Foundation - Education City, Doha, Qatar.
EClinicalMedicine. 2023 Jul 20;62:102102. doi: 10.1016/j.eclinm.2023.102102. eCollection 2023 Aug.
Waning of natural infection protection and vaccine protection highlight the need to evaluate changes in population immunity over time. Population immunity of previous SARS-CoV-2 infection or of COVID-19 vaccination are defined, respectively, as the overall protection against reinfection or against breakthrough infection at a given point in time in a given population.
We estimated these population immunities in Qatar's population between July 1, 2020 and November 30, 2022, to discern generic features of the epidemiology of SARS-CoV-2. Effectiveness of previous infection, mRNA primary-series vaccination, and mRNA booster (third-dose) vaccination in preventing infection were estimated, month by month, using matched, test-negative, case-control studies.
Previous-infection effectiveness against reinfection was strong before emergence of Omicron, but declined with time after a wave and rebounded after a new wave. Effectiveness dropped after Omicron emergence from 88.3% (95% CI: 84.8-91.0%) in November 2021 to 51.0% (95% CI: 48.3-53.6%) in December 2021. Primary-series effectiveness against infection was 84.0% (95% CI: 83.0-85.0%) in April 2021, soon after introduction of vaccination, before waning gradually to 52.7% (95% CI: 46.5-58.2%) by November 2021. Effectiveness declined linearly by ∼1 percentage point every 5 days. After Omicron emergence, effectiveness dropped from 52.7% (95% CI: 46.5-58.2%) in November 2021 to negligible levels in December 2021. Booster effectiveness dropped after Omicron emergence from 83.0% (95% CI: 65.6-91.6%) in November 2021 to 32.9% (95% CI: 26.7-38.5%) in December 2021, and continued to decline thereafter. Effectiveness of previous infection and vaccination against severe, critical, or fatal COVID-19 were generally >80% throughout the study duration.
High population immunity against infection may not be sustained beyond a year, but population immunity against severe COVID-19 is durable with slow waning even after Omicron emergence.
The Biomedical Research Program and the Biostatistics, Epidemiology, and the Biomathematics Research Core, both at Weill Cornell Medicine-Qatar, Ministry of Public Health, Hamad Medical Corporation, Sidra Medicine, Qatar Genome Programme, Qatar University Biomedical Research Center, and Qatar University Internal Grant ID QUCG-CAS-23/24-114.
自然感染保护和疫苗保护作用的减弱凸显了评估人群免疫力随时间变化的必要性。既往新冠病毒感染或新冠疫苗接种的人群免疫力分别定义为在特定时间点特定人群中针对再次感染或突破性感染的总体保护作用。
我们估算了卡塔尔人群在2020年7月1日至2022年11月30日期间的这些人群免疫力，以识别新冠病毒流行病学的一般特征。采用匹配的检测阴性病例对照研究逐月估算既往感染、mRNA基础免疫接种和mRNA加强（第三剂）接种在预防感染方面的有效性。
在奥密克戎毒株出现之前，既往感染对再次感染的有效性很强，但在一波疫情后随时间下降，并在新一波疫情后反弹。奥密克戎毒株出现后，有效性从2021年11月的88.3%（95%置信区间：84.8 - 91.0%）降至2021年12月的51.0%（95%置信区间：48.3 - 53.6%）。基础免疫接种对感染的有效性在2021年4月疫苗接种引入后不久为84.0%（95%置信区间：83.0 - 85.0%），随后逐渐下降，到2021年11月降至52.7%（95%置信区间：46.5 - 58.2%）。有效性每5天线性下降约1个百分点。奥密克戎毒株出现后，有效性从2021年11月的52.7%（95%置信区间：46.5 - 58.2%）降至2021年12月的可忽略不计水平。加强免疫接种的有效性在奥密克戎毒株出现后从2021年11月的83.0%（95%置信区间：65.6 - 91.6%）降至2021年12月的32.9%（95%置信区间：26.7 - 38.5%），此后继续下降。在整个研究期间，既往感染和接种疫苗对重症、危重症或致死性新冠的有效性一般>80%。
针对感染的高人群免疫力可能无法维持超过一年，但针对重症新冠的人群免疫力是持久的，即使在奥密克戎毒株出现后也缓慢下降。
生物医学研究项目以及威尔康奈尔医学院卡塔尔分校（卡塔尔公共卫生部、哈马德医疗公司、西德拉医学中心、卡塔尔基因组计划、卡塔尔大学医学研究中心和卡塔尔大学内部资助项目编号QUCG - CAS - 23/24 - 114）的生物统计学、流行病学和生物数学研究核心。
