Scientific resources

If you want to get into the science behind the COVID-19 pandemic, this is the place where we summarize interesting scientific papers for you to browse through.

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5 May 2020 – Original paper

The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application

The period between infection and first symptoms (incubation period) for SARS-CoV-2 has important implications for surveillance and control activities. This study was conducted on 181 confirmed cases with SARS-CoV-2 infection all located in China outside the Hubei province. It aimed to estimate the incubation period for SARS-CoV-2. The authors found that the average estimated incubation period is 5.1 days, and 97.5% of infected people develop symptoms within 11.5 days. The SARS-CoV-2 incubation period is similar to those of other human coronaviruses. The study estimates that 99% of those exposed to the virus will develop symptoms within 14 days, thus supporting the recommendations for 2-week quarantine.

New-England-Journal-of-Medicine

16 Apr 2020 – Original paper

Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV

To learn about how long virus causing COVID-19 lives on surfaces, researchers conducted a study comparing the survival of two very similar viruses the SARS-CoV-2 (causing COVID-19) and the SARS-CoV (causing SARS) in different environments or surfaces (aerosols, plastic, stainless steel, copper, and cardboard). They showed that SARS-CoV-2 survived 3 hours in aerosols, 4 hrs on copper, 24 hrs on cardboard and more than 72 hrs on plastic and stainless steel, which was very similar for the SARS-CoV. These findings strengthen the importance of frequent hand washing, surface disinfection and the prompt action by infected individuals, such as isolation and wearing masks. The authors conclude that the higher spread rate of SARS-CoV-2 compared with SARS-CoV probably arises from the higher presence of this virus in the upper respiratory tract. In addition, it may be due to the ability of the new virus to be transmitted by asymptomatic people and the “super-spreading” individuals and events (e.g. hospital stays, public events).

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6 Apr 2020 – Original paper

Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy

This is one of the largest studies reporting data on critically ill patients with laboratory-confirmed SARS-CoV2 infection. It includes 1591 patients admitted to intensive care units (ICU) in Lombardy, Italy, from 20th February to 18th March 2020. The median age was 63 years while the majority (82%) were male. From all patients that required intensive care the majority had at least one chronic disease (68%), mostly hypertension (49%), cardio-vascular disease (21%), hypercholesterolemia i.e. high cholesterol (18%) and type 2 diabetes (17%). Virtually all patients required respiratory support (99%). The total ICU mortality was 26%. Older patients (≥64 years) had higher mortality compared with younger patients (≤63 years) (36% vs 15%).

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30 Mar 2020 – Original paper

Estimating the number of infections and the impact of nonpharmaceutical interventions on COVID-19 in 11 European countries

To slow the spread of COVID-19, many European countries have implemented non-pharmaceutical interventions (e.g., case isolation, closure of schools and universities, banning of mass gatherings, etc.). The authors attempt to infer the impact of these interventions across 11 European countries. They estimate 7 – 43 million infected individuals by 28th March, representing 1.88% – 11.43% of the population and the avoidance of 59,000 deaths up to 31st March. According to all presented data, it is critical that the current interventions remain in place and that trends are closely monitored in the coming days and weeks.

New-England-Journal-of-Medicine

30 Mar 2020 – Original paper

Developing Covid-19 Vaccines at Pandemic Speed

Historically, while the H1N1 vaccine was developed rapidly, the SARS and Zika epidemics ended before vaccine development was complete. The pandemic scale of SARS-CoV-2 spread emphasizes the need for the improvement of the vaccine development process and major questions are covered in this study. Currently there is no consensus for the appropriate immunogen as a target and no good animal models to test a vaccine. In the ongoing pandemic it is difficult to predict where to set up clinical trials. There is a huge concern about the adverse effects as well as the efficacy, duration of immunity and/or dosage. Furthermore, when the mortality is high, randomisation is very difficult and the manufacturing would have to be scaled up to commercial levels before substantial safety and immunogenicity (i.e. the ability to provoke an immune response) data are available. 

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27 Mar 2020 – Original paper

Cardiovascular Implications of Fatal Outcomes of Patients With Coronavirus Disease 2019 (COVID-19)

This article highlights the importance of cardio-vascular disease (CVD) and its complications in COVID-19 severity and mortality. Troponin T (TnT) is a protein in muscles, and heart specific TnT when found in blood is a sign of acute myocardial damage, used as a laboratory confirmation of a heart attack. In this study, among 187 patients with COVID-19, 27.8% had higher TnT in blood, and had markedly higher mortality compared with the patients with normal TnT levels (59.6% vs 8.9%). They differed with respect to organs function, blood parameters, inflammation and the need for glucocorticoid therapy and mechanical ventilation. Patients with underlying CVD were more likely to develop higher TnT levels compared with the patients without CVD (54.5% vs 13.2%). Although there are limitations to this study, the main being the limited number and follow-up, it suggests that biomarkers, such as TnT, could be useful for risk stratification and possible early and more aggressive intervention on COVID-19 patients with underlying CVD.

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25 Mar 2020 – Original paper

The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study

За да се забави ширењето на новиот SARS-CoV-2 вирус, во декември 2019 година во Вухан (Кина) биле спроведени строги мерки на социјално дистанцирање. Користејќи математичко моделирање за да симулираат епидемија, авторите го испитувале можниот ефект на контролните мерки врз ширењето на вирусот во Вухан. Нивните резултати посочуваат дека мерките што спречуваат социјално мешање, како што се затворање на училишта и работни места, ќе го забават ширењето на вирусот и ќе го намалат епидемискиот врв. Авторите сугерираат дека е потребно одложување на попуштањето на мерките до април 2020 година, со цел да се зголеми нивниот ефект и да се намали притисокот врз здравствениот систем.

20 Mar 2020 – Original paper

COVID-19 and smoking: A systematic review of the evidence

Previous studies have shown that smokers, compared with non-smokers, are twice more likely to contract influenza, have more severe symptoms and had higher mortality from MERS (another coronavirus disease). This study reports findings from patients hospitalized for COVID-19 infection in China. The conclusion is that current and former smokers develop worse respiratory symptoms and they have a more severe course of the COVID-19 illness, more often requiring intensive care. It is unclear if they are at higher risk of dying from COVID-19. The study does not show whether smokers are more prone to contracting the disease and whether they are more often asymptomatic.

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17 Mar 2020 – Original paper

The proximal origin of SARS-CoV-2

Determining the origin of the virus SARS-CoV-2 is important for a number of reasons, especially for preventing future infections. This paper reviews the current knowledge about this subject, demonstrating that genomic features of SARS-CoV-2 indicate its animal origin. Current evidence suggests that the most likely transmitters are bats. There are two plausible scenarios of its emergence: (1) the virus mutated in the animal host to be able to transfer to and infect humans, or (2) the progenitor virus that already transferred to humans asymptomatically, mutated to cause symptoms of the COVID-19. The authors also underline that there are no indications of laboratory origin of the virus.

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9 Mar 2020 – Original paper

In Vitro Antiviral Activity and Projection of Optimized Dosing Design of Hydroxychloroquine for the Treatment of COVID-19

To date, there is no clinical evidence to support the use of drug therapies in the treatment of COVID-19. In laboratory conditions, the use of hydroxychloroquine sulfate (400 mg given twice daily for 1 day, followed by 200 mg twice daily for the next 4 days) showed better anti-SARS-CoV-2 activity and more tolerable safety profile compared with chloroquine, a widely used anti-malarial drug with immunomodulatory effects (i.e. ability to change the immune response) and sporadically used drug in treatment of COVID-19. This might candidate the hydroxychloroquine for the therapy of COVID-19. However, a well-established randomized control trial in humans is needed to prove hypotheses on its efficacy and safety before it can be widely used.

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9 Mar 2020 – Original paper

How will country-based mitigation measures influence the course of the COVID-19 epidemic?

Dërisa jemi akoma duke mësuar për COVID-19, karakteristikat e njohura epidemiologjike tregojnë për nevojën e masave urgjente për zvogëlsimin dhe kontrollit e përhapjes. Në krahasim me influencën A, COVID-19 ka një shkallë më të lartë fataliteti, inkubacion dhe periudhë infektive më të gjatë gjithashtu ka dhe një numër më të lartë të rasteve asimptomatike ose raste me simptomatikë më të lehta.
Për më tepër, ne jemi 12-18 muaj larg nga prodhimi i vaksinave. Masat aktuale përfshijnë karantina, distancim social në shkallë të gjerë, izolimin e vendeve dhe popullsive të infektuara. Këto masa duhet të zvogëlojnë kurbën e epidemisë për të lejuar kohë për prodhimin e vaksinave. Krijuesit e një linje veprimi po përballen me sfidat për të zvogëluar sëmundshmërinë dhe për të parandaluar efektet e pafavorshme të masave në ekonomi, veçanërisht pasi që kulmi i mëtejshëm ka të ngjarë nëse masat janë të relaksuara pas disa muajsh për të ndihmuar ekonominë.

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24 Feb 2020 – Original paper

Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study

A single-centered, retrospective, observational study described the clinical course and outcomes of 52 critically ill adult patients with SARS-CoV-2 pneumonia, who were admitted to the intensive care unit of a hospital in Wuhan between late December 2019 and 26th January 2020. 67% of the patients had acute respiratory distress syndrome (ARDS) and 71% required mechanical ventilation. 32 patients (62%) died at 28 days, who compared to the survivors, were older, more likely to develop ARDS and were more likely to receive mechanical ventilation.

24 Feb 2020 – Original paper

Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China

An important article presenting the first estimates on the distribution of COVID-19 severity. Among 72,314 cases in China, 62% were confirmed by throat swab tests, of which 81% were mild, 14% severe, and 5% were critical. The overall percentage of deaths within the cases was 2.3%, rising to 8% among 70 to 79 year olds and even 14.8% among the 80 year olds and older. People with existing conditions also had a higher percentage of deaths —10.5% for people with cardiovascular diseases, 7.3% for diabetes, 6.3% for chronic respiratory diseases, 6.0% for hypertension, and 5.6% for cancer. Of the confirmed cases, 3.8% were health workers.

New-England-Journal-of-Medicine

20 Feb 2020 – Original paper

A Novel Coronavirus from Patients with Pneumonia in China, 2019

This is the first article to report isolation of the virus and the initial description of its specific effects and morphology. The authors isolated a pathogen from three hospitalized patients with severe pneumonia in Wuhan, China. Authors designed several specific and sensitive assays targeting some regions of the genome to detect viral RNA in clinical specimens. The virus falls into the genus betacoronavirus, which includes coronaviruses discovered in humans and bats (SARS-CoV). It causes an illness named “novel coronavirus-infected pneumonia” (NCIP-later renamed to COVID-19). The details on the virus structure are promptly shared with the World Health Organization.