洛杉矶抗体检测，4%人口有抗体，新冠病毒感染人数或远超确诊数量 

南加州大学研究人员抽查洛杉矶地区居民血液的初步结果出来了，4.1%试验对象的血液中含有针对新冠病毒的抗体，推断洛杉矶2.8%-5.6%的成年人已被新冠病毒感染，相当于22.1万-44.2万人，是四月初洛杉矶确诊病例的28-55倍，算得感染死亡率0.27%-0.54%。

Los Angeles (April 20, 2020) – USC and the Los Angeles County Department of Public Health (Public Health) today released preliminary results from a collaborative scientific study that suggests infections from the new coronavirus are far more widespread – and the fatality rate much lower — in L.A. County than previously thought.

The results are from the first round of an ongoing study by USC researchers and Public Health officials. They will be conducting antibody testing over time on a series of representative samples of adults to determine the scope and spread of the pandemic across the county.

Based on results of the first round of testing, the research team estimates that approximately 4.1% of the county’s adult population has antibody to the virus. Adjusting this estimate for statistical margin of error implies about 2.8% to 5.6% of the county’s adult population has antibody to the virus— which translates to approximately 221,000 to 442,000 adults in the county who have had the infection. That estimate is 28 to 55 times higher than the 7,994 confirmed cases of COVID-19 reported to the county by the time of the study in early April. The number of COVID-related deaths in the county has now surpassed 600.