Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections may be underestimated because of limited access to testing. We measured SARS-CoV-2 seroprevalence in South Africa every 2 months during July 2020–March 2021 in randomly selected household cohorts in 2 communities. We compared seroprevalence to reported laboratory-confirmed infections, hospitalizations, and deaths to calculate infection–case, infection–hospitalization, and infection–fatality ratios in 2 waves of infection. Post–second wave seroprevalence ranged from 18% in the rural community children <5 years of age, to 59% in urban community adults 35–59 years of age. The second wave saw a shift in age distribution of case-patients in the urban community (from persons 35–59 years of age to persons at the extremes of age), higher attack rates in the rural community, and a higher infection–fatality ratio in the urban community. Approximately 95% of SARS-CoV-2 infections were not reported to national surveillance.

由于检测机会有限，严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 感染可能被低估。我们在 2020 年 7 月至 2021 年 3 月期间每 2 个月在 2 个社区的随机选择的家庭队列中测量了南非的 SARS-CoV-2 血清阳性率。我们将血清阳性率与报告的实验室确诊感染、住院和死亡进行比较，以计算 2 波感染中的感染病例、感染住院率和感染死亡率。第二波后血清阳性率范围从农村社区 5 岁以下儿童的 18% 到城市社区 35-59 岁成人的 59%。第二波看到城市社区病例患者的年龄分布发生变化（从 35-59 岁到极端年龄的人），农村社区的发病率更高，以及城市社区更高的感染-死亡率比。大约 95% 的 SARS-CoV-2 感染没有向国家监测报告。