Lamba Katherine, Bradley Heather, Shioda Kayoko, Sullivan Patrick S, Luisi Nicole, Hall Eric W, Mehrotra Megha L, Lim Esther, Jain Seema, Kamali Amanda, Sanchez Travis, Lopman Benjamin A, Fahimi Mansour, Siegler Aaron J
California Department of Public Health, Richmond, California, USA.
Department of Population Health Sciences, Georgia State University School of Public Health, Atlanta, Georgia, USA.
Open Forum Infect Dis. 2021 Jul 27;8(8):ofab379. doi: 10.1093/ofid/ofab379. eCollection 2021 Aug.
California has reported the largest number of coronavirus disease 2019 (COVID-19) cases of any US state, with more than 3.5 million confirmed as of March 2021. However, the full breadth of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in California is unknown as reported cases only represent a fraction of all infections.
We conducted a population-based serosurvey, utilizing mailed, home-based SARS-CoV-2 antibody testing along with a demographic and behavioral survey. We weighted data from a random sample to represent the adult California population and estimated period seroprevalence overall and by participant characteristics. Seroprevalence estimates were adjusted for waning antibodies to produce statewide estimates of cumulative incidence, the infection fatality ratio (IFR), and the reported fraction.
California's SARS-CoV-2 weighted seroprevalence during August-December 2020 was 4.6% (95% CI, 2.8%-7.4%). Estimated cumulative incidence as of November 2, 2020, was 8.7% (95% CrI, 6.4%-11.5%), indicating that 2 660 441 adults (95% CrI, 1 959 218-3 532 380) had been infected. The estimated IFR was 0.8% (95% CrI, 0.6%-1.0%), and the estimated percentage of infections reported to the California Department of Public Health was 31%. Disparately high risk for infection was observed among persons of Hispanic/Latinx ethnicity and people with no health insurance and who reported working outside the home.
We present the first statewide SARS-CoV-2 cumulative incidence estimate among adults in California. As of November 2020, ~1 in 3 SARS-CoV-2 infections in California adults had been identified by public health surveillance. When accounting for unreported SARS-CoV-2 infections, disparities by race/ethnicity seen in case-based surveillance persist.
加利福尼亚州报告的2019冠状病毒病（COVID-19）病例数在美国各州中最多，截至2021年3月，确诊病例超过350万例。然而，由于报告的病例仅占所有感染病例的一小部分，因此严重急性呼吸综合征冠状病毒2（SARS-CoV-2）在加利福尼亚州的传播全貌尚不清楚。
我们开展了一项基于人群的血清学调查，采用邮寄的家庭式SARS-CoV-2抗体检测以及一项人口统计学和行为学调查。我们对随机样本的数据进行加权，以代表加利福尼亚州的成年人口，并按参与者特征估算总体血清阳性率和特定时期血清阳性率。对血清阳性率估计值进行抗体衰减调整，以得出全州范围的累积发病率、感染致死率（IFR）和报告比例的估计值。
2020年8月至12月期间，加利福尼亚州SARS-CoV-2加权血清阳性率为4.6%（95%置信区间，2.8%-7.4%）。截至2020年11月2日，估计累积发病率为8.7%（95%可信区间，6.4%-11.5%），这表明有2660441名成年人（95%可信区间，1959218-3532380）受到感染。估计感染致死率为0.8%（95%可信区间，0.6%-1.0%），向加利福尼亚州公共卫生部报告的感染病例估计比例为31%。在西班牙裔/拉丁裔族裔人群以及没有医疗保险且报告在外工作的人群中，观察到感染风险异常高。
我们给出了加利福尼亚州成年人中首个全州范围的SARS-CoV-2累积发病率估计值。截至2020年11月，加利福尼亚州成年人中每3例SARS-CoV-2感染病例约有1例已被公共卫生监测发现。在考虑未报告的SARS-CoV-2感染情况时，基于病例的监测中所见的种族/族裔差异依然存在。
