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Results 1 through 20 out of 5896

in category epidemiology


1: Correlation between universal BCG vaccination policy and reduced morbidity and mortality for COVID-19: an epidemiological study

Aaron Miller, Mac Josh Reandelar et al.

354,500 downloads (posted 28 Mar 2020)

COVID-19 has spread to most countries in the world. Puzzlingly, the impact of the disease is different in different countries. These differences are attributed to differences in cultural norms, mitigation efforts, and health infrastructure. Here we propose that national differences in COVID- 19 impact could be partially explained by the different national policies respect to Bacillus Calmette-Guerin (BCG) childhood vaccination. BCG vaccination has been reported to offer broad protection to respiratory infections. We compared large number of countries BCG vaccination policies with the morbidity and mortality for COVID-19. We found that countries without universal policies of BCG vaccination (Italy, Nederland, USA) have been more severely affected compared to countries with universal and long-standing BCG policies. Countries that have a late start of universal BCG policy (Iran, 1984) had high mortality, consistent with the idea that BCG protects the vaccinated elderly population. We also found that BCG vaccination also reduced the number of reported COVID-19 cases in a country. The combination of reduced morbidity and mortality makes BCG vaccination a potential new tool in the fight against COVID-19.


2: COVID-19 Antibody Seroprevalence in Santa Clara County, California

Eran Bendavid, Bianca Mulaney et al.

275,871 downloads (posted 17 Apr 2020)

Background Addressing COVID-19 is a pressing health and social concern. To date, many epidemic projections and policies addressing COVID-19 have been designed without seroprevalence data to inform epidemic parameters. We measured the seroprevalence of antibodies to SARS-CoV-2 in a community sample drawn from Santa Clara County. Methods On April 3-4, 2020, we tested county residents for antibodies to SARS-CoV-2 using a lateral flow immunoassay. Participants were recruited using Facebook ads targeting a sample of individu...


3: Efficacy of hydroxychloroquine in patients with COVID-19: results of a randomized clinical trial

Zhaowei Chen, Jijia Hu et al.

245,705 downloads (posted 30 Mar 2020)

AimsStudies have indicated that chloroquine (CQ) shows antagonism against COVID-19 in vitro. However, evidence regarding its effects in patients is limited. This study aims to evaluate the efficacy of hydroxychloroquine (HCQ) in the treatment of patients with COVID-19. Main methodsFrom February 4 to February 28, 2020, 62 patients suffering from COVID-19 were diagnosed and admitted to Renmin Hospital of Wuhan University. All participants were randomized in a parallel-group trial, 31 patients were assigned to receive an ...


4: Relationship between the ABO Blood Group and the COVID-19 Susceptibility

Jiao Zhao, Yan Yang et al.

194,854 downloads (posted 16 Mar 2020)

The novel coronavirus disease-2019 (COVID-19) has been spreading around the world rapidly and declared as a pandemic by WHO. Here, we compared the ABO blood group distribution in 2,173 patients with COVID-19 confirmed by SARS-CoV-2 test from three hospitals in Wuhan and Shenzhen, China with that in normal people from the corresponding regions. The results showed that blood group A was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups, whereas blood group O was associated with a lower ...


5: Population-level COVID-19 mortality risk for non-elderly individuals overall and for non-elderly individuals without underlying diseases in pandemic epicenters

John P. A. Ioannidis, Cathrine Axfors et al.

167,475 downloads (posted 08 Apr 2020)

OBJECTIVETo evaluate the relative risk of COVID-19 death in people <65 years old versus older individuals in the general population, to provide estimates of absolute risk of COVID-19 death at the population level, and to understand what proportion of COVID-19 deaths occur in non-elderly people without underlying diseases in epicenters of the pandemic. ELIGIBLE DATACountries and US states or major cities with at least 250 COVID-19 deaths as of 4/4/2020 and with information available on death counts according to age stra...


6: OpenSAFELY: factors associated with COVID-19-related hospital death in the linked electronic health records of 17 million adult NHS patients.

The OpenSAFELY Collaborative, Elizabeth J Williamson et al.

158,364 downloads (posted 07 May 2020)

Background Establishing who is at risk from a novel rapidly arising cause of death, and why, requires a new approach to epidemiological research with very large datasets and timely data. Working on behalf of NHS England we therefore set out to deliver a secure and pseudonymised analytics platform inside the data centre of a major primary care electronic health records vendor establishing coverage across detailed primary care records for a substantial proportion of all patients in England. The following results are preli...


7: The Novel Coronavirus, 2019-nCoV, is Highly Contagious and More Infectious Than Initially Estimated

Steven Sanche, Yen Ting Lin et al.

134,662 downloads (posted 11 Feb 2020)

The novel coronavirus (2019-nCoV) is a recently emerged human pathogen that has spread widely since January 2020. Initially, the basic reproductive number, R0, was estimated to be 2.2 to 2.7. Here we provide a new estimate of this quantity. We collected extensive individual case reports and estimated key epidemiology parameters, including the incubation period. Integrating these estimates and high-resolution real-time human travel and infection data with mathematical models, we estimated that the number of infected indi...


8: SARS-CoV-2 RNA concentrations in primary municipal sewage sludge as a leading indicator of COVID-19 outbreak dynamics

Jordan Peccia, Alessandro Zulli et al.

128,384 downloads (posted 22 May 2020)

We report a time course of SARS-CoV-2 RNA concentrations in primary sewage sludge during the Spring COVID-19 outbreak in a northeastern U.S. metropolitan area. SARS-CoV-2 RNA was detected in all environmental samples, and when adjusted for the time lag, the virus RNA concentrations tracked the COVID-19 epidemiological curve. SARS-CoV-2 RNA concentrations were a leading indicator of community infection ahead of compiled COVID-19 testing data and local hospital admissions. Decisions to implement or relax public health mea...


9: Adjusted age-specific case fatality ratio during the COVID-19 epidemic in Hubei, China, January and February 2020

Anthony Hauser, Michel J Counotte et al.

115,189 downloads (posted 06 Mar 2020)

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSBackgroundC_ST_ABSThe epidemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that originated in Wuhan, China in late 2019 is now pandemic. Reliable estimates of death from coronavirus disease 2019 (COVID-19) are essential to guide control efforts and to plan health care system requirements. The objectives of this study are to: 1) simulate the transmission dynamics of SARS-CoV-2 using publicly available surveillance data; 2) give estimates of SARS-CoV-2 mortality adjusted...


10: False positives in reverse transcription PCR testing for SARS-CoV-2

Andrew N Cohen, Bruce Kessel et al.

100,408 downloads (posted 01 May 2020)

Contrary to the practice during previous epidemics, with COVID-19 health authorities have treated a single positive result from a PCR-based test as confirmation of infection, irrespective of signs, symptoms and exposure. This is based on a widespread belief that positive results in these tests are highly reliable. However, evidence from external quality assessments and real-world data indicate enough a high enough false positive rate to make positive results highly unreliable over a broad range of scenarios. This has cl...


11: Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold

M. Gabriela M. Gomes, Rodrigo M. Corder et al.

89,935 downloads (posted 02 May 2020)

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads, the susceptible subpopulation is depleted causing the incidence of new cases to decline. Variation in individual susceptibility or exposure to infection exacerbates this effect. Individuals that are more susceptible or more exposed tend to be infected earlier, depleting the susceptible subpopulation of those who are at higher risk of infection. This selective depletion of susceptibles intensifies the deceleration in incidence. Eventually, susceptib...


12: Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19)

Hiroshi Nishiura, Hitoshi Oshitani et al.

88,417 downloads (posted 03 Mar 2020)

ObjectiveTo identify common features of cases with novel coronavirus disease (COVID-19) so as to better understand what factors promote secondary transmission including superspreading events. MethodsA total of 110 cases were examined among eleven clusters and sporadic cases, and investigated who acquired infection from whom. The clusters included four in Tokyo and one each in Aichi, Fukuoka, Hokkaido, Ishikawa, Kanagawa and Wakayama prefectures. The number of secondary cases generated by each primary case was calculate...


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

Damian Guerra, Daniel J Guerra

83,200 downloads (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...


14: Emergence and spread of a SARS-CoV-2 variant through Europe in the summer of 2020

Emma B Hodcroft, Moira Zuber et al.

80,662 downloads (posted 28 Oct 2020)

Following its emergence in late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic resulting in unprecedented efforts to reduce transmission and develop therapies and vaccines (WHO Emergency Committee, 2020; Zhu et al., 2020). Rapidly generated viral genome sequences have allowed the spread of the virus to be tracked via phylogenetic analysis (Worobey et al., 2020; Hadfield et al., 2018; Pybus et al., 2020). While the virus spread globally in early 2020 before borders closed,...


15: Viral cultures for COVID-19 infectivity assessment. Systematic review

Tom Jefferson, Elizabeth A Spencer et al.

77,838 downloads (posted 04 Aug 2020)

Objective To review the evidence from studies comparing SARS-CoV-2 culture, with the results of reverse transcriptase polymerase chain reaction (RT-PCR). Methods We searched LitCovid, medRxiv, Google Scholar and the WHO Covid-19 database for Covid-19 using the terms viral culture or viral replication and associated synonyms up to 10 September 2020. We carried out citation matching and included studies reporting attempts to culture or observe SARS-CoV-2 matching with cutoffs for RT-PCR positivity. One reviewer extracted ...


16: Full lockdown policies in Western Europe countries have no evident impacts on the COVID-19 epidemic.

Thomas A. J. Meunier

73,740 downloads (posted 01 May 2020)

This phenomenological study assesses the impacts of full lockdown strategies applied in Italy, France, Spain and United Kingdom, on the slowdown of the 2020 COVID-19 outbreak. Comparing the trajectory of the epidemic before and after the lockdown, we find no evidence of any discontinuity in the growth rate, doubling time, and reproduction number trends. Extrapolating pre-lockdown growth rate trends, we provide estimates of the death toll in the absence of any lockdown policies, and show that these strategies might not h...


17: Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients

John A Lednicky, Michael Lauzardo et al.

71,537 downloads (posted 04 Aug 2020)

Background - There currently is substantial controversy about the role played by SARS-CoV-2 in aerosols in disease transmission, due in part to detections of viral RNA but failures to isolate viable virus from clinically generated aerosols. Methods - Air samples were collected in the room of two COVID-19 patients, one of whom had an active respiratory infection with a nasopharyngeal (NP) swab positive for SARS-CoV-2 by RT-qPCR. By using VIVAS air samplers that operate on a gentle water-vapor condensation principle, mate...


18: Predicting the Trajectory of Any COVID19 Epidemic From the Best Straight Line

Michael Levitt, Andrea Scaiewicz et al.

68,889 downloads (posted 28 Jun 2020)

A pipeline involving data acquisition, curation, carefully chosen graphs and mathematical models, allows analysis of COVID-19 outbreaks at 3,546 locations world-wide (all countries plus smaller administrative divisions with data available). Comparison of locations with over 50 deaths shows all outbreaks have a common feature: H(t) defined as loge(X(t)/X(t 1)) decreases linearly on a log scale, where X(t) is the total number of Cases or Deaths on day, t (we use ln for loge). The downward slopes vary by about a factor of ...


19: Sentinel surveillance of SARS-CoV-2 in wastewater anticipates the occurrence of COVID-19 cases

Gemma Chavarria-MirĂ³, Eduard Anfruns-Estrada et al.

66,377 downloads (posted 13 Jun 2020)

SARS-CoV-2 was detected in Barcelona sewage long before the declaration of the first COVID-19 case, indicating that the infection was present in the population before the first imported case was reported. Sentinel surveillance of SARS-CoV-2 in wastewater would enable adoption of immediate measures in the event of future COVID-19 waves.


20: Social distancing strategies for curbing the COVID-19 epidemic

Stephen Kissler, Christine Tedijanto et al.

62,944 downloads (posted 24 Mar 2020)

The SARS-CoV-2 pandemic is straining healthcare resources worldwide, prompting social distancing measures to reduce transmission intensity. The amount of social distancing needed to curb the SARS-CoV-2 epidemic in the context of seasonally varying transmission remains unclear. Using a mathematical model, we assessed that one-time interventions will be insufficient to maintain COVID-19 prevalence within the critical care capacity of the United States. Seasonal variation in transmission will facilitate epidemic control du...