Abstract：
OBJECTIVE: SARS-CoV-2 infection could cause persistent lung injury or indicate potential genetic susceptibilities. Although infection-elicited hybrid immunity could protect against severe COVID-19, it remains unknown whether recent infection could reduce pneumonia risk during reinfection due to insufficient viral and chest computed tomography (CT) screening.
METHODS: A total of 15,598 patients, 96% fully vaccinated and 52% boosted, from Xiangyang, China, who had symptomatic COVID-19 and chest CT scans during the first Omicron BF.7 wave in December 2022 to January 2023, were followed through the second Omicron XBB.1.5 wave between May and August 2023. A total of 17,968 second-wave patients with COVID-19 with chest CT scans but without previous symptomatic COVID-19 were enrolled as first-time infection controls.
RESULTS: A total of 19.6% (3,061 of 15,598) first-wave patients were diagnosed with pneumonia. Among second-wave reinfected patients, only 0.2% (four of 2202) developed pneumonia, which was lower than the 1.7% (311 of 17,968) pneumonia prevalence among the second-wave first-time patients, with an adjusted relative risk of 0.11 (95% confidence interval: 0.04-0.29). A total of 1.3% (40 of 3,039) first-wave pneumonia survivors showed residual abnormal patterns in follow-up CT scans within 8 months after pneumonia diagnosis.
CONCLUSIONS: In a highly vaccinated population, previous symptomatic Omicron infection within 8 months reduced pneumonia risk during reinfection. Uninfected individuals might need up-to-date vaccination to reduce pneumonia risk.
METHODS: A total of 15,598 patients, 96% fully vaccinated and 52% boosted, from Xiangyang, China, who had symptomatic COVID-19 and chest CT scans during the first Omicron BF.7 wave in December 2022 to January 2023, were followed through the second Omicron XBB.1.5 wave between May and August 2023. A total of 17,968 second-wave patients with COVID-19 with chest CT scans but without previous symptomatic COVID-19 were enrolled as first-time infection controls.
RESULTS: A total of 19.6% (3,061 of 15,598) first-wave patients were diagnosed with pneumonia. Among second-wave reinfected patients, only 0.2% (four of 2202) developed pneumonia, which was lower than the 1.7% (311 of 17,968) pneumonia prevalence among the second-wave first-time patients, with an adjusted relative risk of 0.11 (95% confidence interval: 0.04-0.29). A total of 1.3% (40 of 3,039) first-wave pneumonia survivors showed residual abnormal patterns in follow-up CT scans within 8 months after pneumonia diagnosis.
CONCLUSIONS: In a highly vaccinated population, previous symptomatic Omicron infection within 8 months reduced pneumonia risk during reinfection. Uninfected individuals might need up-to-date vaccination to reduce pneumonia risk.
摘要：
目的：SARS-CoV-2感染可引起持续性肺损伤或提示潜在的遗传易感性。虽然感染引发的混合免疫可以预防严重的COVID-19，但由于病毒和胸部CT筛查不足，最近的感染是否可以降低再次感染期间肺炎的风险仍然未知。
方法：15,598名患者，96%完全接种疫苗，52%加强疫苗接种，来自襄阳,中国在2022年12月至2023年1月的第一次omicronBF.7波中有症状的COVID-19和胸部CT扫描，随后在2023年5月至8月之间进行了第二次omicronXBB.1.5波。17,968例接受胸部CT扫描但没有症状性COVID-19病史的第二波COVID-19患者作为首次感染对照。
结果：19.6%(3,061/15,598)的第一波患者被诊断为肺炎。在第二波再次感染的患者中，只有0.2%(4/2,202)患有肺炎，低于第二波首次患者的1.7%(311/17,968)肺炎患病率，调整后相对风险（RR）为0.11（95%CI：0.04-0.29）。1.3%(40/3,039)的第一波肺炎幸存者在肺炎诊断后8个月内的随访CT扫描中显示出残留的异常模式。
结论：在高度接种疫苗的人群中，在8个月内之前有症状的omicron感染降低了再感染期间的肺炎风险.未感染的人可能需要最新的疫苗接种，以降低肺炎的风险。
方法：15,598名患者，96%完全接种疫苗，52%加强疫苗接种，来自襄阳,中国在2022年12月至2023年1月的第一次omicronBF.7波中有症状的COVID-19和胸部CT扫描，随后在2023年5月至8月之间进行了第二次omicronXBB.1.5波。17,968例接受胸部CT扫描但没有症状性COVID-19病史的第二波COVID-19患者作为首次感染对照。
结果：19.6%(3,061/15,598)的第一波患者被诊断为肺炎。在第二波再次感染的患者中，只有0.2%(4/2,202)患有肺炎，低于第二波首次患者的1.7%(311/17,968)肺炎患病率，调整后相对风险（RR）为0.11（95%CI：0.04-0.29）。1.3%(40/3,039)的第一波肺炎幸存者在肺炎诊断后8个月内的随访CT扫描中显示出残留的异常模式。
结论：在高度接种疫苗的人群中，在8个月内之前有症状的omicron感染降低了再感染期间的肺炎风险.未感染的人可能需要最新的疫苗接种，以降低肺炎的风险。
