No abstract

We compared severe acute respiratory syndrome–related coronavirus-2 seroprevalence estimated from commercial laboratory residual sera and a community household survey in metropolitan Atlanta during April-May 2020 and found these two estimates to be similar (4.94% versus 3.18%). Compared with more representative surveys, commercial sera can provide an approximate measure of seroprevalence.

Background Monitoring of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody prevalence can complement case reporting to inform more accurate estimates of SARS-CoV-2 infection burden, but few studies have undertaken repeated sampling over time on a broad geographic scale. Methods We performed serologic testing on a convenience sample of residual sera obtained from persons of all ages, at ten sites in the United States from March 23 through August 14, 2020, from routine clinical testing at commercial laboratories. We age-sex-standardized our seroprevalence rates using census population projections and adjusted for laboratory assay performance. Confidence intervals were generated with a two-stage bootstrap. We used Bayesian modeling to test whether seroprevalence changes over time were statistically significant. Results Seroprevalence remained below 10% at all sites except New York and Florida, where it reached 23.2% and 13.3%, respectively. Statistically significant increases in seroprevalence followed peaks in reported cases in New York, South Florida, Utah, Missouri and Louisiana. In the absence of such peaks, some significant decreases were observed over time in New York, Missouri, Utah, and Western Washington. The estimated cumulative number of infections with detectable antibody response continued to exceed reported cases in all sites. Conclusions Estimated seroprevalence was low in most sites, indicating that most people in the U.S. have not been infected with SARS-CoV-2 as of July 2020. The majority of infections are likely not reported. Decreases in seroprevalence may be related to changes in healthcare-seeking behavior, or evidence of waning of detectable anti-SARS CoV-2 antibody levels at the population level. Thus, seroprevalence estimates may underestimate the cumulative incidence of infection.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii.In humans, Q fever can manifest in an acute or chronic form. Acute Q fever typically presents as a febrile illness, although some patients may develop pneumonia or hepatitis. Examinations of previous outbreaks of acute Q fever have suggested that nearly half of infected individuals are asymptomatic (Anderson et al., 2013;Bamberg et al., 2007).Chronic infections with C. burnetii are rare, developing in less than 5% of infected persons (Fenollar et al., 2001). Forms of chronic Q fever include endocarditis, infection of vascular grafts or aneurysms, osteomyelitis and osteoarthritis. Persons most at risk for chronic Q