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Results 1 through 20 out of 20

in category epidemiology


1: Viral infection and Transmission in a large well-traced outbreak caused by the Delta SARS-CoV-2 variant

Baisheng Li, Aiping Deng et al.

41 tweets (posted 12 Jul 2021)

We report the first local transmission of the SARS-CoV-2 Delta variant in mainland China. All 167 infections could be traced back to the first index case. Daily sequential PCR testing of the quarantined subjects indicated that the viral loads of Delta infections, when they first become PCR+, were on average ~1000 times greater compared to A/B lineage infections during initial epidemic wave in China in early 2020, suggesting potentially faster viral replication and greater infectiousness of Delta during early infection. We performed high-quality sequencing on samples from 126 individuals. Reliable epidemiological data meant that, for 111 transmission events, the donor and recipient cases were known. The estimated transmission bottleneck size was 1-3 virions with most minor intra-host single nucleotide variants (iSNVs) failing to transmit to the recipients. However, transmission heterogeneity of SARS-CoV-2 was also observed. The transmission of minor iSNVs resulted in at least 4 of the 30 substitutions identified in the outbreak, highlighting the contribution of intra-host variants to population level viral diversity during rapid spread. Disease control activities, such as the frequency of population testing, quarantine during pre-symptomatic infection, and level of virus genomic surveillance should be adjusted in order to account for the increasing prevalence of the Delta variant worldwide.


2: Mask mandate and use efficacy in state-level COVID-19 containment

Damian Guerra, Daniel J Guerra

20 tweets (posted 25 May 2021)

Background: Containment of the COVID-19 pandemic requires evidence-based strategies to reduce transmission. Because COVID-19 can spread via respired droplets, many states have mandated mask use in public settings. Randomized control trials have not clearly demonstrated mask efficacy against respiratory viruses, but observational studies suggest greater mask compliance may be associated with lower infection rates. We hypothesized that statewide mask mandates and mask use are associated with lower COVID-19 case growth rat...


3: Breakthrough Symptomatic COVID-19 Infections Leading to Long Covid: Report from Long Covid Facebook Group Poll

Daisy Massey, Diana Berrent et al.

10 tweets (posted 26 Jul 2021)

Vaccines have been shown to be extremely effective in preventing COVID-19 hospitalizations and deaths. However, a question remains whether vaccine breakthrough cases can still lead to Post-Acute Sequelae of SARS-CoV-2 (PASC), also known as Long Covid. To address this question, the Survivor Corps group, a grassroots COVID-19 organization focused on patient support and research, posted a poll to its 169,900 members that asked about breakthrough cases, Long Covid, and hospitalizations. 1,949 people who self-report being fu...


4: Protection of previous SARS-CoV-2 infection is similar to that of BNT162b2 vaccine protection: A three-month nationwide experience from Israel

Yair Goldberg, Micha Mandel et al.

7 tweets (posted 24 Apr 2021)

Worldwide shortage of vaccination against SARS-CoV-2 infection while the pandemic is still uncontrolled leads many states to the dilemma whether or not to vaccinate previously infected persons. Understanding the level of protection of previous infection compared to that of vaccination is critical for policy making. We analyze an updated individual-level database of the entire population of Israel to assess the protection efficacy of both prior infection and vaccination in preventing subsequent SARS-CoV-2 infection, hosp...


5: Prominent Spatiotemporal Waves of COVID-19 Incidence in the United States: Implications for Causality, Forecasting, and Control

Hawre Jalal, Kyueun Lee et al.

5 tweets (posted 03 Jul 2021)

Better understanding of the spatiotemporal structure of the COVID-19 epidemic in the USA may help inform more effective prevention and control strategies. By analyzing daily COVID-19 case data in the United States, Mexico and Canada, we found four continental-scale epidemic wave patterns, including travelling waves, that spanned multiple state and even international boundaries. These major epidemic patterns co-varied strongly with continental-scale seasonal temperature change patterns. Geo-contiguous states shared simil...


6: Long-term symptoms after SARS-CoV-2 infection in school children: population-based cohort with 6-months follow-up. Short Report

Thomas Radtke, Agne Ulyte et al.

4 tweets (posted 18 May 2021)

Although nobody doubts the existence of long COVID in children, it is still unclear to what extent children are affected. The Ciao Corona study is a longitudinal cohort investigating SARS-CoV-2 seroprevalence and clustering of cases among around 2500 children from 55 randomly selected primary and secondary schools in the canton of Zurich in Switzerland. Between June 2020 and April 2021, we completed three testing phases where we collected venous blood for serological analysis (ABCORA 2.0 test) and asked about symptoms w...


7: Evidence for treatment with estradiol for women with SARS-CoV-2 infection

Ute Seeland, Flaminia Coluzzi et al.

3 tweets (posted 24 Aug 2020)

BACKGROUND Given that an individual's age and gender are strongly predictive of COVID-19 outcomes, do such factors imply anything about preferable therapeutic options? METHODS An analysis of electronic health records for a large (68,466-case), international COVID-19 cohort, in five-year age strata, revealed age-dependent sex differences. In particular, we surveyed the effects of systemic hormone administration in women. The primary outcome for estradiol therapy was death. Odds Ratios (ORs) and Kaplan-Meier survival curv...


8: Prevention and Attenuation of COVID-19 by BNT162b2 and mRNA-1273 Vaccines

Mark G Thompson, Jefferey L Burgess et al.

3 tweets (posted 03 Jun 2021)

BACKGROUNDInformation is limited on messenger RNA (mRNA) BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) COVID-19 vaccine effectiveness (VE) in preventing SARS-CoV-2 infection or attenuating disease when administered in real-world conditions. METHODSProspective cohorts of 3,975 healthcare personnel, first responders, and other essential and frontline workers completed weekly SARS-CoV-2 testing during December 14, 2020--April 10 2021. Self-collected mid-turbinate nasal swabs were tested by qualitative and quantitativ...


9: Illness duration and symptom profile in a large cohort of symptomatic UK school-aged children tested for SARS-CoV-2

Erika Molteni, Carole H. Sudre et al.

2 tweets (posted 08 May 2021)

BackgroundIn children, SARS-CoV-2 is usually asymptomatic or causes a mild illness of short duration. Persistent illness has been reported; however, its prevalence and characteristics are unclear. We aimed to determine illness duration and characteristics in symptomatic UK school-aged children tested for SARS-CoV-2 using data from the COVID Symptom Study, the largest citizen participatory epidemiological study to date. MethodsData from 258,790 children aged 5-17 years were reported by an adult proxy between 24 March 20...


10: COVID-19 infection and subsequent psychiatric morbidity, sleep problems and fatigue: analysis of an English primary care cohort of 226,521 positive patients

Kathryn M. Abel, Matthew J Carr et al.

1 tweets (posted 26 Jun 2021)

Objectives The primary hypothesis was that the risk of incident or repeat psychiatric illness, fatigue and sleep problems increased following COVID-19 infection. The analysis plan was pre-registered (https://osf.io/n2k34/). Design Matched cohorts were assembled using a UK primary care registry (the CPRD-Aurum database). Patients were followed-up for up to 10 months, from 1st February 2020 to 9th December 2020. Setting Primary care database of 11,923,499 adults (>16 years). Participants From 232,780 adults with a positiv...


11: Distinguishing Viruses Responsible for Influenza-Like Illness

Julie Spencer, Deborah P. Shutt et al.

1 tweets (posted 05 Feb 2020)

The many respiratory viruses that cause influenza-like illness (ILI) are reported and tracked as one entity, defined by the CDC as a group of symptoms that include a fever of 100 degrees Fahrenheit and a cough and/or a sore throat. In the United States alone, ILI impacts 9-49 million people every year. While tracking ILI as a single clinical syndrome is informative in many respects, the underlying viruses differ in their parameters and outbreak properties. Most existing models treat either a single respiratory virus or ...


12: Novel risk factors for Coronavirus disease-associated mucormycosis (CAM): a case control study during the outbreak in India

Umang Arora, Megha Priyadarshi et al.

1 tweets (posted 26 Jul 2021)

Background: The epidemiology of the Coronavirus-disease associated mucormycosis (CAM) syndemic is poorly elucidated. We aimed to identify risk factors that may explain the burden of cases and help develop preventive strategies. Methods: We performed a case-control study comparing cases diagnosed with CAM and those who had recovered from COVID-19 without developing mucormycosis (controls). Information on comorbidities, glycemic control, and practices related to COVID-19 prevention and treatment was recorded. Results: 352...


13: Population based estimates of comorbidities affecting risk for complications from COVID-19 in the US

Mary L. Adams, David L. Katz et al.

1 tweets (posted 02 Apr 2020)

We used 2017 Behavioral Risk Factor Surveillance System (BRFSS) data (N=444,649) to estimate the proportion of US adults who report comorbidities that suggest heightened risk of complications from COVID-19. Co-morbidities included cardiovascular disease, chronic obstructive pulmonary disease (COPD), diabetes, asthma, hypertension, and/or cancer other than skin, based on data from China. Overall 45.4% (95% CI 45.1-45.7) of adults reported any of the 6 comorbidities, increasing from 19.8% (19.1-20.4) for ages 18-29 years ...


14: Reconstructing the course of the COVID-19 epidemic over 2020 for US states and counties: results of a Bayesian evidence synthesis model

Melanie H Chitwood, Marcus Russi et al.

1 tweets (posted 20 Jun 2020)

Reported COVID-19 cases and deaths provide a delayed and incomplete picture of SARS-CoV-2 infections in the United States (US). Accurate estimates of both the timing and magnitude of infections are needed to characterize viral transmission dynamics and better understand COVID-19 disease burden. We estimated time trends in SARS-CoV-2 transmission and other COVID-19 outcomes for every county in the US, from the first reported COVID-19 case in January 13, 2020 through January 1, 2021. To do so we employed a Bayesian modeli...


15: Practical considerations for measuring the effective reproductive number, Rt

Katelyn M Gostic, Lauren McGough et al.

1 tweets (posted 21 Jun 2020)

Estimation of the effective reproductive number, Rt, is important for detecting changes in disease transmission over time. During the COVID-19 pandemic, policymakers and public health officials are using Rt to assess the effectiveness of interventions and to inform policy. However, estimation of Rt from available data presents several challenges, with critical implications for the interpretation of the course of the pandemic. The purpose of this document is to summarize these challenges, illustrate them with examples fr...


16: SARS-CoV-2 waves in Europe: A 2-stratum SEIRS model solution

Levan Djaparidze, Federico Lois

1 tweets (posted 13 Oct 2020)

In order to design actionable SARS-CoV-2 strategies, we extended the SEIRS model to support stratified isolation levels for healthy <60 and vulnerable individuals. At first, we forced isolation levels to be uniform, showing that daily deaths curves of all metropolitan areas in the analysis can be fitted using homogeneous Ro=3.3. In the process, we established the possibility that an extremely short infectiousness period of 2 days coupled with 5 days exposure may be responsible for the multiple deaths valleys observed du...


17: Household COVID-19 risk and in-person schooling

Justin Lessler, M. Kate Grabowski et al.

1 tweets (posted 01 Mar 2021)

In-person schooling has proved contentious and difficult to study throughout the SARS-CoV-2 pandemic. Data from a massive online survey in the United States indicates an increased risk of COVID-19-related outcomes among respondents living with a child attending school in-person. School-based mitigation measures are associated with significant reductions in risk, particularly daily symptoms screens, teacher masking, and closure of extra-curricular activities. With seven or more mitigation measures, the association betwee...


18: SARS-CoV-2 infection and risk of clinical sequelae during the post-acute phase: a retrospective cohort study

Sarah E Daugherty, Yinglong Guo et al.

1 tweets (posted 12 Mar 2021)

Objective: Clinical sequelae have not been well characterized during the post-acute phase of SARS-CoV-2 among adults 18 to 65 years old, and this study sought to fill that gap by evaluating excess risk and relative hazards for developing incident clinical sequelae during the post-acute phase. Design: Retrospective cohort study including three propensity-matched groups. Setting: This study merged three data sources from a large United States health plan: a large national administrative claims database, an outpatient lab ...


19: Evidence for increased breakthrough rates of SARS-CoV-2 variants of concern in BNT162b2 mRNA vaccinated individuals

Talia Kustin, Noam Harel et al.

1 tweets (posted 09 Apr 2021)

The SARS-CoV-2 pandemic has been raging for over a year, creating global detrimental impact. The BNT162b2 mRNA vaccine has demonstrated high protection levels, yet apprehension exists that several variants of concerns (VOCs) can surmount the immune defenses generated by the vaccines. Neutralization assays have revealed some reduction in neutralization of VOCs B.1.1.7 and B.1.351, but the relevance of these assays in real life remains unclear. Here, we performed a case-control study that examined whether BNT162b2 vaccine...


20: Risk factors for long COVID: analyses of 10 longitudinal studies and electronic health records in the UK

Ellen J. Thompson, Dylan M. Williams et al.

1 tweets (posted 25 Jun 2021)

The impact of long COVID is increasingly recognised, but risk factors are poorly characterised. We analysed questionnaire data on symptom duration from 10 longitudinal study (LS) samples and electronic healthcare records (EHR) to investigate sociodemographic and health risk factors associated with long COVID, as part of the UK National Core Study for Longitudinal Health and Wellbeing. Methods Analysis was conducted on 6,899 adults self-reporting COVID-19 from 45,096 participants of the UK LS, and on 3,327 cases assigned...