[Source: US Centers for Disease Control and Prevention (CDC), MMWR Morbidity and Mortality Weekly Report, full page: (LINK). Abstract, edited.]
Population Point Prevalence of SARS-CoV-2 Infection Based on a Statewide Random Sample — Indiana, April 25–29, 2020
Early Release / July 21, 2020 / 69
Nir Menachemi, PhD1,2; Constantin T. Yiannoutsos, PhD1; Brian E. Dixon, PhD1,2; Thomas J. Duszynski, MPH1; William F. Fadel, PhD1; Kara K. Wools-Kaloustian, MD3; Nadia Unruh Needleman, MS1; Kristina Box, MD4; Virginia Caine, MD5; Connor Norwood, PhD6; Lindsay Weaver, MD4; Paul K. Halverson, DrPH1
Corresponding author: Nir Menachemi, email@example.com.
1Indiana University Richard M. Fairbanks School of Public Health, Indianapolis, Indiana; 2Regenstrief Institute, Inc., Indianapolis, Indiana; 3Indiana University School of Medicine, Indianapolis, Indiana; 4Indiana State Department of Health; 5Marion County Department of Public Health, Indianapolis, Indiana; 6Indiana Family and Social Services Administration.
All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Nir Menachemi reports a grant from State of Indiana which funded this study. Virginia Caine reports that she is a member of the MMWR Editorial Board. Brian E. Dixon and William F. Fadel report grants from the Indiana State Department of Health. Paul K. Halverson reports a grant from the State of Indiana. No other potential conflicts of interest were disclosed.
Suggested citation for this article: Menachemi N, Yiannoutsos CT, Dixon BE, et al. Population Point Prevalence of SARS-CoV-2 Infection Based on a Statewide Random Sample — Indiana, April 25–29, 2020. MMWR Morb Mortal Wkly Rep. ePub: 21 July 2020. DOI: http://dx.doi.org/10.15585/mmwr.mm6929e1
- What is already known about this topic?
- No state has conducted a random sample study to determine the population prevalence of SARS-CoV-2 infection at a given point in time.
- What is added by this report?
- In a random sample of Indiana residents aged ≥12 years, the estimated prevalence of current or previous SARS-CoV-2 infection in late April 2020 was 2.79%. Among persons with active infection, 44% reported no symptoms.
- What are the implications for public health practice?
- The number of reported cases represents an estimated one of 10 infections. Given that many persons in Indiana remain susceptible, adherence to evidence-based public health mitigation measures (e.g., social distancing, consistent and correct use of face coverings, and hand hygiene) is needed to reduce surge in hospitalizations and prevent morbidity and mortality from COVID-19.
Population prevalence of persons infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), varies by subpopulation and locality. U.S. studies of SARS-CoV-2 infection have examined infections in nonrandom samples (1) or seroprevalence in specific populations* (2), which are limited in their generalizability and cannot be used to accurately calculate infection-fatality rates. During April 25–29, 2020, Indiana conducted statewide random sample testing of persons aged ≥12 years to assess prevalence of active infection and presence of antibodies to SARS-CoV-2; additional nonrandom sampling was conducted in racial and ethnic minority communities to better understand the impact of the virus in certain racial and ethnic minority populations. Estimates were adjusted for nonresponse to reflect state demographics using an iterative proportional fitting method. Among 3,658 noninstitutionalized participants in the random sample survey, the estimated statewide point prevalence of active SARS-CoV-2 infection confirmed by reverse transcription–polymerase chain reaction (RT-PCR) testing was 1.74% (95% confidence interval [CI] = 1.10–2.54); 44.2% of these persons reported no symptoms during the 2 weeks before testing. The prevalence of immunoglobulin G (IgG) seropositivity, indicating past infection, was 1.09% (95% CI = 0.76–1.45). The overall prevalence of current and previous infections of SARS-CoV-2 in Indiana was 2.79% (95% CI = 2.02–3.70). In the random sample, higher overall prevalences were observed among Hispanics and those who reported having a household contact who had previously been told by a health care provider that they had COVID-19. By late April, an estimated 187,802 Indiana residents were currently or previously infected with SARS-CoV-2 (9.6 times higher than the number of confirmed cases [17,792]) (3), and 1,099 residents died (infection-fatality ratio = 0.58%). The number of reported cases represents only a fraction of the estimated total number of infections. Given the large number of persons who remain susceptible in Indiana, adherence to evidence-based public health mitigation and containment measures (e.g., social distancing, consistent and correct use of face coverings, and hand hygiene) is needed to reduce surge in hospitalizations and prevent morbidity and mortality from COVID-19.
Keywords: SARS-CoV-2; COVID-19; Serology; Seroprevalence; Indiana; USA.