Empirical epidemiologic studies

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• **Research resource for designing epidemiologic studies
  To minimize the proliferation of one-off survey items, encourage comparisons across samples, and facilitate data integration and collaboration, a trans-NIH working group co-led by the National Institute on Aging (NIA) and the Office of Behavioral and Social Sciences Research (OBSSR) are making existing COVID-19 survey items available in a survey item repository available as a resource for researchers interested in assessing COVID-19 specific domains.
• *Prevalence of Asymptomatic SARS-CoV-2 Infection: A Narrative Review
  Daniel P. Oran, AM, Eric J. Topol, MD. Annals of Internal Medicine. 3 June 2020;
  Asymptomatic persons seem to account for approximately 40% to 45% of SARS-CoV-2 infections, and they can transmit the virus to others for an extended period, perhaps longer than 14 days. Asymptomatic infection may be associated with subclinical lung abnormalities, as detected by computed tomography.
  
• *Seroprevalence of SARS-CoV-2–Specific Antibodies Among Adults in Los Angeles County, California, on April 10-11, 2020
  Neeraj Sood, PhD; Paul Simon, MD; Peggy Ebner, BA; Daniel Eichner, PhD; Jeffrey Reynolds, MA; Eran Bendavid, MD; Jay Bhattacharya, MD, PhD. JAMA
  May 18, 2020.
  In this community seroprevalence study in Los Angeles County, the prevalence of antibodies to SARS-CoV-2 was 4.65%. The estimate implies that approximately 367,000 adults had SARS-CoV-2 antibodies, which is substantially greater than the 8430 cumulative number of confirmed infections in the county on April 10.
  BE SURE TO READ THE COMMENTS POSTED WITH THE ARTICLE.
• A COVID-19 Transmission within a family cluster by presymptomatic infectors in China
  Guoqing Qian, Naibin Yang, Ada Hoi Yan Ma, Liping Wang, et al. Clinical Infectious Diseases, 23 March 2020
  Abstract: We report a COVID-19 family cluster caused by a presymptomatic case. There were 9 family members, including 8 laboratory-confirmed with COVID-19, and a 6-year-old child had no evidence of infection. Amongst the 8 patients, one adult and one 13-month-old infant were asymptomatic, one adult was diagnosed as having severe pneumonia.
  
• Adolescent with COVID-19 as the Source of an Outbreak at a 3-Week Family Gathering — Four States, June–July 2020
  Noah G. Schwartz, MD; Anne C. Moorman, MPH; Anna Makaretz, ScM; Karen T. Chang, PhD, et al. MMWR Early Release, Oct. 5, 2020; 69
  This outbreak highlights several important issues. First, children and adolescents can serve as the source for COVID-19 outbreaks within families, even when their symptoms are mild (2). Better understanding of transmission by children and adolescents in different settings is needed to refine public health guidance. Second, this investigation provides evidence of the benefit of physical distancing as a mitigation strategy to prevent SARS-CoV-2 transmission. None of the six family members who maintained outdoor physical distance without face masks during two visits to the family gathering developed symptoms; the four who were tested for SARS-CoV-2 had negative test results. Third, rapid antigen tests generally have lower sensitivity (84.0%–97.6%) compared with RT-PCR testing; negative results should be confirmed with RT-PCR if used for persons with high pretest probability of infection, such as those with a known exposure (4). Fourth, regardless of negative test results, persons should self-quarantine for 14 days after a known exposure (5) or after travel when mandated by state, territorial, tribal, or local authorities (6). Finally, SARS-CoV-2 can spread efficiently during gatherings, especially with prolonged, close contact. Physical distancing, face mask use, and hand hygiene reduce transmission; gatherings should be avoided when physical distancing and face mask use are not possible (7).
• Airborne transmission potential
• Articles published in CDC MMWR Mortality & Weekly Report
• Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility
  Anne Kimball; Kelly M. Hatfield; Melissa Arons; Allison James, et al.
  Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020. Weekly / April 3, 2020 / 69(13);377–381
  Following identification of a case of coronavirus disease 2019 (COVID-19) in a health care worker, 76 of 82 residents of an SNF were tested for SARS-CoV-2; 23 (30.3%) had positive test results, approximately half of whom were asymptomatic or presymptomatic on the day of testing.... Seven days after testing, 10 of these 13 previously asymptomatic residents had developed symptoms and were recategorized as presymptomatic at the time of testing. The reverse transcription–polymerase chain reaction (RT-PCR) testing cycle threshold (Ct) values indicated large quantities of viral RNA in asymptomatic, presymptomatic, and symptomatic residents, suggesting the potential for transmission regardless of symptoms.
• COVID-19: in the footsteps of Ernest Shackleton
  Alvin J Ing, Christine Cocks, Jeffery Peter Green. Thorax. http://dx.doi.org/10.1136/thoraxjnl-2020-215091
  Abstract
  We describe what we believe is the first instance of complete COVID-19 testing of all passengers and crew on an isolated cruise ship during the current COVID-19 pandemic. Of the 217 passengers and crew on board, 128 tested positive for COVID-19 on reverse transcription–PCR (59%). Of the COVID-19-positive patients, 19% (24) were symptomatic; 6.2% (8) required medical evacuation; 3.1% (4) were intubated and ventilated; and the mortality was 0.8% (1). The majority of COVID-19-positive patients were asymptomatic (81%, 104 patients). We conclude that the prevalence of COVID-19 on affected cruise ships is likely to be significantly underestimated, and strategies are needed to assess and monitor all passengers to prevent community transmission after disembarkation.
• Vic deleted line about Overnight Summer School Retreat
• Cumulative incidence and diagnosis of SARS-CoV-2 infection in New York
  Eli S.Rosenberg, James M.Tesoriero, Elizabeth M.Rosenthal, RakkooChung, et al. Annals of Epidemiology 17 June 2020; journal pre-proof.
  We conducted a statewide seroprevalence study among a 15,101 patron convenience sample at 99 grocery stores in 26 counties throughout NYS. SARS-CoV-2 cumulative incidence was estimated from antibody reactivity by first post-stratification weighting then adjusting by antibody test characteristics. The percent diagnosed was estimated by dividing diagnoses by estimated infection-experienced adults.
  Based on 1,887 of 15,101 reactive results (12.5%), estimated cumulative incidence through March 29 was 14.0% (95% CI: 13.3-14.7%), corresponding to 2,139,300 (95% CI: 2,035,800-2,242,800) infection-experienced adults. Cumulative incidence was highest in New York City (NYC) 22.7% (95% CI: 21.5-24.0%) and higher among Hispanic/Latino (29.2%), non-Hispanic black/African American (20.2%), and non-Hispanic Asian (12.4%) than non-Hispanic white adults (8.1%, p<.0001). An estimated 8.9% (95% CI: 8.4-9.3%) of infections in NYS were diagnosed, with diagnosis highest among adults ≥55 years (11.3%, 95% CI: 10.4-12.2%).
• Estimating COVID-19 antibody seroprevalence in Santa Clara County, California.A re-analysis of Bendavid et al.
  Stephen T. Bennett and Mark Steyvers, University of California, Irvine, Preprint April 25, 2020
  Abstract: A recent study by Bendavid et al. claimed that the rate of infection of COVID-19 in Santa Clara county was between 2.49% and 4.16%, 50-85 times higher than the number of officially confirmed cases.... We jointly estimate the sensitivity and specificity of the test kit along with rate of infection with a simple Bayesian model, arriving at lower estimates of the rate of COVID-19 in Santa Clara county. Re-analyzing their data, we find that the rate of infection was likely between 0.27%and 3.21%.
• Implementation and Evolution of Mitigation Measures, Testing, and Contact Tracing in the National Football League, August 9–November 21, 2020
  Christina D. Mack, Erin B. Wasserman, Cria G. Perrine, Adam MacNeil, et al. MMWR Morb Mortal Wkly Rep. ePub: 25 January 2021.
• In one Italian town, we showed mass testing could eradicate the coronavirus
  Andrea Crisanti and Antonio Cassone, The Guardian, Fri 20 Mar 2020 03.00 EDT, Last modified on Thu 26 Mar 2020 11.10 EDT
  Beginning on 6 March , along with researchers at the University of Padua and the Red Cross, we tested all residents of Vò, a town of 3,000 inhabitants near Venice – including those who did not have symptoms. This allowed us to quarantine people before they showed signs of infection and stop the further spread of coronavirus. In this way, we eradicated coronavirus in under 14 days.
  
• Modes of contact and risk of transmission in COVID-19 among close contacts
  Lei Luo, Dan Liu, Xin-long Liao, Xian-bo Wu, Qin-long Jing et al. MedRxiv, 020.03.24.20042606
  We included 4950 closes contacts from Guangzhou, and extracted data including modes of contact, laboratory testing, clinical characteristics of confirmed cases and source cases. We used logistic regression analysis to explore the risk factors associated with infection of close contacts. Results Among 4950 closes contacts, the median age was 38.0 years, and males accounted for 50.2% (2484). During quarantine period, 129 cases (2.6%) were diagnosed, with 8 asymptomatic (6.2%), 49 mild (38.0%), and 5 (3.9%) severe to critical cases.
• NIH begins study to quantify undetected cases of coronavirus infection
  NIH News release, April 10, 2020
  A new study has begun recruiting at the National Institutes of Health in Bethesda, Maryland, to determine how many adults in the United States without a confirmed history of infection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), have antibodies to the virus. The presence of antibodies in the blood indicates a prior infection. In this “serosurvey,” researchers will collect and analyze blood samples from as many as 10,000 volunteers to provide critical data for epidemiological models. [However, it's not clear if there is any sampling frame or design.]
• Preventing and Mitigating SARS-CoV-2 Transmission — Four Overnight Camps, Maine, June–August 2020
  Laura L. Blaisdell, MD; Wendy Cohn, PhD; Jeff R. Pavell, DO; Dana S. Rubin, MD; Jeffrey E. Vergales, MD. MMWR Morb Mortal Wkly Rep. ePub: 26 August 2020. DOI: http://dx.doi.org/10.15585/mmwr.mm6935e1
  During the 2020 summer camp season, four Maine overnight camps with 1,022 attendees from 41 states and international locations implemented a multilayered prevention and mitigation strategy that was successful in identifying and isolating three asymptomatic COVID-19 cases and preventing secondary transmission.
• SARS-CoV-2 Transmission and Infection Among Attendees of an Overnight Camp — Georgia, June 2020
  Christine M. Szablewski, DVM; Karen T. Chang, PhD; Marie M. Brown, MPH; Victoria T. Chu, MD; et al. Morbidity and Mortality Weekly / August 7, 2020 / 69(31);1023–1025
  These findings demonstrate that SARS-CoV-2 spread efficiently in a youth-centric overnight setting, resulting in high attack rates among persons in all age groups, despite efforts by camp officials to implement most recommended strategies to prevent transmission. Asymptomatic infection was common and potentially contributed to undetected transmission, as has been previously reported (1–4). This investigation adds to the body of evidence demonstrating that children of all ages are susceptible to SARS-CoV-2 infection (1–3) and, contrary to early reports (5,6), might play an important role in transmission (7,8). The multiple measures adopted by the camp were not sufficient to prevent an outbreak in the context of substantial community transmission.
• Seroprevalence of Antibodies to SARS-CoV-2 in Six Sites in the United States, March 23-May 3, 2020
  Fiona P. Havers, Carrie Reed, Travis W. Lim, Joel M. Montgomery, et al. medRxiv preprint, posted June 26, 2020
  Our seroprevalence estimates suggest that for five of six U.S. sites, from late March to early May 2020, >10 times more SARS-CoV-2 infections occurred than the number of reported cases.
• Seroprevalence of SARS-CoV-2 Among Frontline Health Care Personnel in a Multistate Hospital Network — 13 Academic Medical Centers, April–June 2020
  Wesley H. Self, MD; Mark W. Tenforde, MD, PhD; William B. Stubblefield, MD; Leora R. Feldstein, PhD et al. MMWR, August 31, 2020 / 69
  Among 3,248 personnel observed, 6% had antibody evidence of previous SARS-CoV-2 infection; 29% of personnel with SARS-CoV-2 antibodies were asymptomatic in the preceding months, and 69% had not previously received a diagnosis of SARS-CoV-2 infection. Prevalence of SARS-CoV-2 antibodies was lower among personnel who reported always wearing a face covering while caring for patients (6%), compared with those who did not (9%).
  
• Testing and social distancing measures by state
  Kate Eisenberg, Blog, April 10, 2020
  Testing and social distancing measures by state
• Texas 'mom and pop' business flooded with orders for helmet ventilators amid coronavirus crisis
  Lisa Cavazuti, Cynthia McFadden and Rich Schapiro, NBC News, March 31, 2020
  Sea-Long Medical Systems has drawn huge interest from hospitals and foreign countries seeking alternatives in treating COVID-19 patients amid a ventilator shortage. News article includes a link to the JAMA article on the RCT: https://www.ncbi.nlm.nih.gov/pubmed/27179847
• Unprecedented nationwide blood studies seek to track U.S. coronavirus spread
  Jon Cohen, Science, April 7, 2020
  Science talked to Michael Busch, a transfusion specialist based at the University of California, San Francisco (UCSF), who has studied human blood infections caused by every imaginable virus. He directs the Vitalant Research Institute, a nonprofit that’s linked to 170 blood donation centers in the country. Busch described three large sero-surveys SARS-CoV-2 antibody, planned or underway.
• Using influenza surveillance networks to estimate state-specific prevalence of SARS-CoV-2 in the United States
  Justin D. Silverman, Nathaniel Hupert, Alex D. Washburne. Science Translational Medicine 22 Jun 2020:
  Detection of SARS-CoV-2 infections to date has relied heavily on RT-PCR testing. However, limited test availability, high false-negative rates, and the existence of asymptomatic or sub-clinical infections have resulted in an under-counting of the true prevalence of SARS-CoV-2. Here, we show how influenza-like illness (ILI) outpatient surveillance data can be used to estimate the prevalence of SARS-CoV-2. We found a surge of non
  -influenza ILI above the seasonal average in March 2020 and showed that this surge correlated with COVID-19 case counts across states. If 1/3 of patients infected with SARS-CoV-2 in the US sought care, this ILI surge would have corresponded to more than 8.7 million new SARS-CoV
  -2 infections across the US during the three-week period from March 8 to March 28, 2020. Combining excess ILI counts with the date of onset of community transmission in the US, we also show that the early epidemic in the US was unlikely to have been doubling slower than every 4 days. Together these results suggest a conceptual model for the COVID-19 epidemic in the US characterized by rapid spread across the US with over 80% infected patients remaining undetected. We emphasize the importance of testing these findings with seroprevalence data and discuss the broader potential to use syndromic surveillance for early detection and understanding of emerging infectious diseases.