Cumulative incidence of SARS-CoV-2 infections among adults in Georgia, USA, August-December 2020

Background: Reported COVID-19 cases underestimate the true number of SARS-CoV-2 infections. Data on all infections, including asymptomatic infection, are needed to guide state testing and prevention programs. To minimize biases in estimates from seroprevalence surveys and reported cases, we conducted a state-wide probability survey of Georgia households and estimated cumulative incidence of SARS-CoV-2 infections adjusted for antibody waning. Methods: From August to December 2020, we mailed kits to self-collect specimens (nasal swabs and blood spots) to a random sample of Georgia addresses. One randomly-selected adult household member completed a survey and returned specimens for virus and antibody testing. We estimated cumulative incidence of SARS-CoV-2 infections adjusted for waning antibodies, reported fraction, and infection fatality ratio (IFR). Differences in seropositivity among demographic, geographic and clinical subgroups were explored with weighted prevalence ratios (PR). Results: Among 1,370 Georgia adult participants, adjusted cumulative incidence of SARS-CoV-2 was 16.1% (95% credible interval (CrI): 13.5-19.2%) as of November 16, 2020. The reported fraction was 26.6% and IFR was 0.78%. Non-Hispanic Black (PR: 2.03, CI 1.0, 4.1) and Hispanic adults (PR: 1.98, CI 0.74, 5.31) were more likely than non-Hispanic White adults to be seropositive. Seropositivity in metropolitan Atlanta's Fulton and DeKalb counties was similar to seropositivity elsewhere in Georgia (7.8% vs. 8.8%). Conclusions: As of mid-November 2020, one in 6 adults in Georgia had been infected with SARS-CoV-2. The scope of the COVID-19 epidemic in Georgia is likely substantially underestimated by reported cases.

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Risk factors, symptom reporting, healthcare-seeking behaviour and adherence to public health guidance: protocol for Virus Watch, a prospective community cohort study

BMJ Open ◽

10.1136/bmjopen-2020-048042 ◽

2021 ◽

Vol 11 (6) ◽

pp. e048042

Author(s):

Andrew Hayward ◽

Ellen Fragaszy ◽

Jana Kovar ◽

Vincent Nguyen ◽

Sarah Beale ◽

...

Keyword(s):

Public Health ◽

Cohort Study ◽

Online Survey ◽

Respiratory Infections ◽

Advisory Group ◽

Antibody Testing ◽

Public Health Action ◽

Nasal Swabs ◽

Health Action ◽

Minority Ethnic

IntroductionThe coronavirus (COVID-19) pandemic has caused significant global mortality and impacted lives around the world. Virus Watch aims to provide evidence on which public health approaches are most likely to be effective in reducing transmission and impact of the virus, and will investigate community incidence, symptom profiles and transmission of COVID-19 in relation to population movement and behaviours.Methods and analysisVirus Watch is a household community cohort study of acute respiratory infections in England and Wales and will run from June 2020 to August 2021. The study aims to recruit 50 000 people, including 12 500 from minority ethnic backgrounds, for an online survey cohort and monthly antibody testing using home fingerprick test kits. Nested within this larger study will be a subcohort of 10 000 individuals, including 3000 people from minority ethnic backgrounds. This cohort of 10 000 people will have full blood serology taken between October 2020 and January 2021 and repeat serology between May 2021 and August 2021. Participants will also post self-administered nasal swabs for PCR assays of SARS-CoV-2 and will follow one of three different PCR testing schedules based on symptoms.Ethics and disseminationThis study has been approved by the Hampstead National Health Service (NHS) Health Research Authority Ethics Committee (ethics approval number 20/HRA/2320). We are monitoring participant queries and using these to refine methodology where necessary, and are providing summaries and policy briefings of our preliminary findings to inform public health action by working through our partnerships with our study advisory group, Public Health England, NHS and government scientific advisory panels.

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SARS-CoV-2 Cumulative Incidence and Period Seroprevalence: Results from a Statewide Population-Based Serosurvey in California

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab379 ◽

2021 ◽

Author(s):

Katherine Lamba ◽

Heather Bradley ◽

Kayoko Shioda ◽

Patrick S Sullivan ◽

Nicole Luisi ◽

...

Keyword(s):

Public Health ◽

Cumulative Incidence ◽

Population Based ◽

Antibody Testing ◽

California Department ◽

Incidence Estimate ◽

Home Based ◽

Weighted Data ◽

Race Ethnicity ◽

California Population

Abstract Background California has reported the largest number of COVID-19 cases of any U.S. state, with more than 3.5 million confirmed as of March 2021. However, the full breadth of SARS-CoV-2 transmission in California is unknown since reported cases only represent a fraction of all infections. Methods 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. Results 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 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. Conclusions We present the first statewide SARS-CoV-2 cumulative incidence estimate among adults in California. As of November 2020, approximately one in three 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.

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High Seroprevalence of Anti-SARS-CoV-2 Antibodies in Chelsea, Massachusetts

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa579 ◽

2020 ◽

Vol 222 (12) ◽

pp. 1955-1959 ◽

Cited By ~ 7

Author(s):

Vivek Naranbhai ◽

Christina C Chang ◽

Wilfredo F Garcia Beltran ◽

Tyler E Miller ◽

Michael G Astudillo ◽

...

Keyword(s):

Point Of Care ◽

Asymptomatic Infection ◽

Disease Prevalence ◽

Lateral Flow Immunoassay ◽

High Seroprevalence ◽

Antibody Testing ◽

Significant Burden ◽

Convenience Sampling ◽

Risk Communities

Abstract SARS-CoV-2 antibody testing allows quantitative determination of disease prevalence, which is especially important in high-risk communities. We performed anonymized convenience sampling of 200 currently asymptomatic residents of Chelsea, the epicenter of COVID-19 illness in Massachusetts, by BioMedomics SARS-CoV-2 combined IgM-IgG point-of-care lateral flow immunoassay. The seroprevalence was 31.5% (17.5% IgM+IgG+, 9.0% IgM+IgG−, and 5.0% IgM−IgG+). Of the 200 participants, 50.5% reported no symptoms in the preceding 4 weeks, of which 24.8% (25/101) were seropositive, and 60% of these were IgM+IgG−. These data are the highest seroprevalence rates observed to date and highlight the significant burden of asymptomatic infection.

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Trends in SARS-CoV-2 seroprevalence in Massachusetts estimated from newborn screening specimens

10.1101/2021.10.29.21265678 ◽

2021 ◽

Author(s):

Kevin C Ma ◽

Jaime E Hale ◽

Yonatan Grad ◽

Galit Alter ◽

Katherine Luzuriaga ◽

...

Keyword(s):

Newborn Screening ◽

Cumulative Incidence ◽

Diagnostic Testing ◽

Credible Interval ◽

Dried Blood Spots ◽

Multilevel Regression ◽

Public Health Policies ◽

Seroprevalence Data ◽

Test Specificity ◽

Good Concordance

Background. Estimating the cumulative incidence of SARS-CoV-2 is essential for setting public health policies. We leveraged de-identified Massachusetts newborn screening specimens to generate an accessible, retrospective source of maternal antibodies for estimating statewide SARS-CoV-2 seroprevalence in a non-test-seeking population. Methods. We analyzed 72,117 newborn dried blood spots collected from November 2019 through December 2020, representing 337 towns and cities across Massachusetts. Seroprevalence was estimated for the general Massachusetts population after correcting for imperfect test specificity and nonrepresentative sampling using Bayesian multilevel regression and poststratification. Results. Statewide seroprevalence was estimated to be 0.03% (90% credible interval (CI) [0.00, 0.11]) in November 2019 and rose to 1.47% (90% CI [1.00, 2.13]) by May 2020, following sustained SARS-CoV-2 transmission in the spring. Seroprevalence plateaued from May onwards, reaching 2.15% (90% CI [1.56, 2.98]) in December 2020. Seroprevalence varied substantially by community and was particularly associated with community percent non-Hispanic Black (β = 0.024, 90% CI [0.004, 0.044]); i.e., a 10% increase in community percent non-Hispanic Black was associated with a 27% higher odds of seropositivity. Seroprevalence estimates had good concordance with reported case counts and wastewater surveillance for most of 2020, prior to the resurgence of transmission in winter. Conclusions. Cumulative incidence of SARS-CoV-2 protective antibody in Massachusetts was low as of December 2020, indicating that a substantial fraction of the population was still susceptible. Maternal seroprevalence data from newborn screening can inform longitudinal trends and identify cities and towns at highest risk, particularly in settings where widespread diagnostic testing is unavailable.

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COVID-19 cumulative incidence, asymptomatic infections, and fatality in Long Island, NY, January–August 2020: A cohort of World Trade Center responders

PLoS ONE ◽

10.1371/journal.pone.0254713 ◽

2021 ◽

Vol 16 (7) ◽

pp. e0254713

Author(s):

Olga Morozova ◽

Sean A. P. Clouston ◽

Jennifer Valentine ◽

Alexander Newman ◽

Melissa Carr ◽

...

Keyword(s):

Cumulative Incidence ◽

World Trade ◽

Long Island ◽

World Trade Center ◽

Case Fatality ◽

Antibody Testing ◽

Igg Antibody ◽

Cross Sectional ◽

Increased Risk ◽

Trade Center

Background New York City and Long Island, NY were early foci of the COVID-19 epidemic in the US. The effects of COVID-19 on different sub-populations, and its key epidemiologic parameters remain unknown or highly uncertain. We investigated the epidemiology of COVID-19 from January to August of 2020 in an established academic monitoring cohort of N = 9,697 middle-aged World Trade Center responders residing in Long Island, NY. Methods A seroprevalence survey and a series of cross-sectional surveys were nested in a prospective cohort study. Measures included IgG antibody testing, SARS-CoV-2 polymerase chain reaction (PCR) testing, review of electronic medical records, and surveys of symptoms. Correlates of infection were analyzed with multivariable logistic regression. Results The cohort was predominantly men in their mid-fifties; 6,597 cohort members were successfully contacted (68%); 1,042 (11%) individuals participated in the seroprevalence survey; and 369 individuals (5.6% of 6,597 study participants) underwent PCR testing. The estimated standardized cumulative incidence was 21.9% (95%CI: 20.1–23.9%), the asymptomatic proportion was 16.4% (36/219; 95%CI: 11.8–22.0%), the case hospitalization ratio was 9.4% (36/385; 95%CI: 6.6–12.7%), the case fatality ratio was 1.8% (7/385; 95%CI: 0.7–3.7%), and the hospitalization fatality ratio was 8.3% (3/36; 95%CI: 1.8–22.5%). Confirmed SARS-CoV-2 infection was associated with younger age, race/ethnicity, and being currently employed. Conclusions The results of the present study suggest a high cumulative incidence of SARS-CoV-2 among WTC responders in the spring and summer of 2020 and contribute to narrowing the plausible range of the proportion of infections that exhibit no symptoms. An increased risk of infection among younger employed individuals is likely to reflect a higher probability of exposure to the virus, and the racial disparities in the infection risk warrant further investigation.

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High Rate of Asymptomatic Carriage Associated with Variant Strain Omicron

10.1101/2021.12.20.21268130 ◽

2021 ◽

Author(s):

Nigel Garret ◽

Asa Tapley ◽

Jessica Andriesen ◽

Ishen Seocharan ◽

Leigh H Fisher ◽

...

Keyword(s):

Vaccine Trial ◽

Asymptomatic Infection ◽

High Rate ◽

Asymptomatic Carriage ◽

African Health ◽

Persons Living With Hiv ◽

High Prevalence ◽

Nasal Swabs ◽

Rapid Dissemination ◽

Living With Hiv

The early widespread dissemination of Omicron indicates the urgent need to better understand the transmission dynamics of this variant, including asymptomatic spread among immunocompetent and immunosuppressed populations. In early December 2021, the Ubuntu clinical trial, designed to evaluate efficacy of the mRNA-1273 vaccine (Moderna) among persons living with HIV (PLWH), began enrolling participants. Nasal swabs are routinely obtained at the initial vaccination visit, which requires participants to be clinically well to receive their initial jab. Of the initial 230 participants enrolled between December 2 and December 17, 2021, 71 (31%) were PCR positive for SARS-CoV-2: all of whom were subsequently confirmed by S gene dropout to be Omicron; 48% of the tested samples had cycle threshold (CT) values <25 and 18% less than 20, indicative of high titers of asymptomatic shedding. Asymptomatic carriage rates were similar in SARS-CoV-2 seropositive and seronegative persons (27% respectively). These data are in stark contrast to COVID-19 vaccine studies conducted pre-Omicron, where the SARS-CoV-2 PCR positivity rate at the first vaccination visit ranged from <1%-2.4%, including a cohort of over 1,200 PLWH largely enrolled in South Africa during the Beta outbreak. We also evaluated asymptomatic carriage in a sub study of the Sisonke vaccine trial conducted in South African health care workers, which indicated 2.6% asymptomatic carriage during the Beta and Delta outbreaks and subsequently rose to 16% in both PLWH and PHLWH during the Omicron period. These findings strongly suggest that Omicron has a much higher rate of asymptomatic carriage than other VOC and this high prevalence of asymptomatic infection is likely a major factor in the widespread, rapid dissemination of the variant globally, even among populations with high prior rates of SARS-COV-2 infection.

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Estimated incidence of COVID-19 illness and hospitalization — United States, February–September, 2020

Clinical Infectious Diseases ◽

10.1093/cid/ciaa1780 ◽

2020 ◽

Cited By ~ 2

Author(s):

Heather Reese ◽

A Danielle Iuliano ◽

Neha N Patel ◽

Shikha Garg ◽

Lindsay Kim ◽

...

Keyword(s):

United States ◽

The United States ◽

Asymptomatic Infection ◽

Uncertainty Interval ◽

Assay Sensitivity ◽

True Number ◽

Testing Practices ◽

Outpatient Settings ◽

Inform Resource Allocation ◽

The U.S

Abstract Background In the United States, laboratory confirmed coronavirus disease 2019 (COVID-19) is nationally notifiable. However, reported case counts are recognized to be less than the true number of cases because detection and reporting are incomplete and can vary by disease severity, geography, and over time. Methods To estimate the cumulative incidence SARS-CoV-2 infections, symptomatic illnesses, and hospitalizations, we adapted a simple probabilistic multiplier model. Laboratory-confirmed case counts that were reported nationally were adjusted for sources of under-detection based on testing practices in inpatient and outpatient settings and assay sensitivity. Results We estimated that through the end of September, 1 of every 2.5 (95% Uncertainty Interval (UI): 2.0–3.1) hospitalized infections and 1 of every 7.1 (95% UI: 5.8–9.0) non-hospitalized illnesses may have been nationally reported. Applying these multipliers to reported SARS-CoV-2 cases along with data on the prevalence of asymptomatic infection from published systematic reviews, we estimate that 2.4 million hospitalizations, 44.8 million symptomatic illnesses, and 52.9 million total infections may have occurred in the U.S. population from February 27–September 30, 2020. Conclusions These preliminary estimates help demonstrate the societal and healthcare burdens of the COVID-19 pandemic and can help inform resource allocation and mitigation planning.

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Quantifying the contribution of asymptomatic infection to the cumulative incidence

Epidemiology and Infection ◽

10.1017/s0950268817000115 ◽

2017 ◽

Vol 145 (6) ◽

pp. 1256-1258 ◽

Cited By ~ 2

Author(s):

D. CHAMPREDON ◽

S. M. MOGHADAS

Keyword(s):

Mathematical Model ◽

Infectious Diseases ◽

Cumulative Incidence ◽

Analytical Formula ◽

Asymptomatic Infection ◽

Simple Analytical Formula

SUMMARYMany infectious diseases in humans may manifest with no or mild symptoms. While numerous studies have estimated the proportion of infectious individuals in whom symptoms are absent during the entire course of infection, the contribution of asymptomatic cases to the overall cumulative incidence is difficult to untangle. Here, with a mathematical model, we provide a simple analytical formula to quantify this contribution and highlight the potential for large errors that can arise when naively estimating it.

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Female (Under) Representation in Exercise Thermoregulation Research

Sports Medicine - Open ◽

10.1186/s40798-021-00334-6 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Kate P. Hutchins ◽

David N. Borg ◽

Aaron J. E. Bach ◽

Joshua J. Bon ◽

Geoffrey M. Minett ◽

...

Keyword(s):

Menstrual Cycle ◽

Sports Medicine ◽

Emergency Services ◽

Professional Sports ◽

Credible Interval ◽

Representation Of Women ◽

Adult Participants ◽

Future Work ◽

Exertional Heat Stress ◽

Exercise Thermoregulation

Abstract Background Despite an increasing rate of women participating in professional sports, emergency services, and military settings where they are exposed to exertional heat stress, our understanding of female thermoregulation and the detrimental effects of heat on women’s performance, especially regarding the menstrual cycle, is limited. This review aimed to quantify the representation of women in exercise thermoregulation research between 2010 and 2019 and the frequency that these articles reported details pertaining to female participants’ menstrual cycle to determine the volume of novel research that is directly relevant to this growing population. Methods Original exercise thermoregulatory studies published in three major sports medicine databases (PubMed, MEDLINE, and SPORTDiscus) between 2010 and 2019 were surveyed. Articles were screened to determine the number of female and male participants in the study and whether studies involving women reported menstrual orientation or phase. Research involving healthy adult participants and an exercise protocol with a thermoregulatory outcome measure were included in the review. Results A total of 1407 articles were included in the review, involving 28,030 participants. The annual representation of women ranged from a mean of 11.6% [95% credible interval (CI); 9.2, 14.3] to 17.8% [95% CI; 15.2, 20.6] across the 10 years, indicating studies predominantly included men. Nonetheless, there was a small statistical increase in the overall proportion of women, with a mean overall proportion change of 0.7% [95% CI; 0.2, 1.2] per year. The increase appeared to be driven by a reduction in the number of studies including only men, rather than studies including more women alongside men, or increased women-only studies. Less than one third of articles involving women reported the menstrual orientation of participants and less than one quarter reported both menstrual orientation and phase. Summary/Conclusion This study shows that women were proportionally underrepresented in exercise thermoregulation research during the past decade and the majority of studies did not report menstrual cycle details of female participants. Researchers should consider including women in future work where their inclusion could contribute meaningful data that enhance the evidence-based and ultimately improves our comprehension of women’s thermal physiology.

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Canine SARS-CoV-2 infection

10.21203/rs.3.rs-18713/v1 ◽

2020 ◽

Cited By ~ 3

Author(s):

Thomas HC Sit ◽

Christopher J Brackman ◽

Sin Ming Ip ◽

Karina WS Tam ◽

Pierra YT Law ◽

...

Keyword(s):

Hong Kong ◽

Amino Acid ◽

Respiratory Disease ◽

Asymptomatic Infection ◽

Viral Sequence ◽

Rt Pcr ◽

Viral Loads ◽

Nasal Swabs ◽

Household Members ◽

Negative Gene

Abstract SARS-CoV-2 emerged in Wuhan in December 2019 and has caused the pandemic respiratory disease, COVID-19. Following what is presumed to be an initial zoonotic transmission event, the virus is now spreading efficient in humans. Very little is known about the susceptibility of domestic mammals kept as pets to this virus. Samples were collected over a 13-day period from a 17 year-old neutered male Pomeranian in Hong Kong SA that was taken into isolation after two members of the household tested positive for the virus. Nasal swabs were consistently positive on the five occasions the dog was tested using quantitative RT- PCR with viral loads between 7.5xE2 to 2.6 x10E4 RNA copies per mL of sample. The dog remained asymptomatic. Cultures attempted on three RT-PCR positive nasal samples were negative. Gene sequences from samples from two household members were identical. The viral sequence from the dog differed at three nucleotide positions; two of these resulted in amino acid changes but their significance is yet to be determined. Seroconversion was not detected but this was expected given the asymptomatic infection and low virus load. The evidence suggests that this is an instance of human-to-animal transmission of SARS-COV-2. It is likely that we could see similar events in other infected households. We do not have information yet on whether this virus can cause illness in dogs but no specific signs were seen in this dog. Whether infected dogs could transmit the virus to other animals or back to humans remains unknown. In this case it did not appear to have occurred.

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