A New Coronavirus, a New Epidemic, Many Open Questions
Latest update: May 07, 2021
The new coronavirus that jumped from some animal to a person in the city of Wuhan at the end of last year has managed, in only a few weeks, to draw huge attention from the media, scientists and the international community. On January 30, the WHO declared the epidemic a public health emergency of international concern (PHEIC).
The epidemic is evolving very fast and with it, the knowledge we have on this new virus. From not knowing anything at beginnings of 2020, the scientific community has managed to isolate it, sequence it, identify it, and develop a diagnostic test.
However, as occurs with every new epidemic, there are many open questions that will be answered as the epidemic evolves and as scientists manage to get a better grasp of the virus’s behaviour.
COVID-19: Scientific Updates
Policy Documents | COVID-19 and Response Strategy
Support our research against COVID-19. Donate here!
1. What is the New Coronavirus SARS-CoV-2 or COVID-19?
The new coronavirus, first called 2019-nCoV and officially renamed as SARS-CoV2 (the virus) and COVID-19 (the disease), belongs to the family of coronavirus, which owe the name to crown-like spikes on their surface. Most described coronavirus are found in birds or mammals, particularly bats.
The new coronavirus is called SARS-CoV2 because its genetic sequence is very similar to that of SARS, another coronavirus that appeared for first (and only) time in 2002 and caused a pandemic with more than 8,000 infected people and 800 deaths. Another coronavirus that causes severe disease in humans is MERS-CoV, identified for the first time in 2012 in the Middle East and associated with camels.
2. How Did SARS-CoV2 Appear?
The SARS-CoV-2 virus is very similar to other coronaviruses found in bats. Although exactly how, when and where the new coronavirus emerged remains unknown, the most likely scenario is that it jumped from a bat to an intermediary mammal host (maybe the pangolin) and from there to humans. The first reported outbreak of cases is associated with a wildlife market in Wuhan. However, a WHO-led mission recently concluded that the market probably served to amplify the outbreak but that there may have been cases before and beyond the market.
3. How Does COVID19 Spread?
The main transmission route of the new coronavirus is by air, through small droplets expelled when someone coughs, sneezes or talks, as well as aerosols (smaller drops capable of travelling further and remain suspended in air) that accumulate in closed and badly ventilated spaces. The virus can also be transmitted by touching your eyes, nose, or mouth after touching contaminated surfaces, although this transmission route seems to be rare.
In contrast with SARS that was only transmitted by people with symptoms, the new coronavirus can be transmitted a day or two before the onset of symptoms (presymptomatic) or even by people who never develop clinical symptoms (asymptomatic). This considerably hinders containment efforts aimed at limiting viral spread and is the reason why everyone should wear a facemask and adhere to social distancing.
COVID-19 can be transmitted from one person to another with considerable ease. To date, the WHO estimates that the R0, or basic reproduction number, the virus is somewhere between 1.4 and 2.5, although other estimates give a range between 2 and 3. This means that every infected person can in turn infect 2 to 3 other people, although “superspreader” people or events play an important role in transmission - it is believed that 20% of cases may account for up to 80% of new infections.
To control an epidemic, the R0 needs to be below 1.
How is COVID-19 diagnosed?
Active infections: look for the virus: SARS-Cov2 infection occurs mainly in the respiratory tract. This is why the diagnostic tests that rely on the amplification of viral gene sequences by PCR must be done on nose or throat swabs. It is important to bear in mind that PCR tests do not distinguish between viable virus and viral fragments. In addition, the result can depend of how the sample is taken.
Other diagnostic tests detect viral proteins (rapid antigen tests) - they are less sensitive (i.e. they do not detect all those infected) but are faster and easier to use, and can identify people who have high viral loads and therefore are highly infectious.
Past infections: Look for antibodies. Another type of test detects virus-specific antibodies. In this case, a blood sample is sufficient. This test detects individuals who have been previously exposed to the virus and could therefore be immune. For the moment, the serological tests used vary widely in terms of sensitivity (capacity to detect positive cases) and specificity (capacity to distinguish from other viruses), so the results must be interpreted with caution. Furthermore, having antibodies to the virus does not guarantee immunity to it. Inversely, cellular immunity (virus-specific T cells) has been observed even in recovered patients with undetectable antibodies.
4. What are the Symptoms of COVID-19?
The main symptoms are fever, cough and difficulty to breathe. However, in a small percentage of patients, the first symptoms may be headache, nausea or diarrhea. In fact, the virus can also infect other cells of the body, including intestinal cells, which would explain the diarrheas and the presence of viral RNA in stool.
Loss of smell and taste seems to be frequent among infected individuals and could be among the first signs of disease.
An excessive inflammation
SARS-CoV-2 starts replicating in the upper respiratory tract (throat) and in some cases reaches the lungs, where it can cause severe damage (pneumonia and acute respiratory distress). The virus can also infect other cells such as those lining the blood vessels and organs such as the heart, the liver, the kidney and the pancreas. Altogether, this leads to an excessive -and potentially lethal- inflammatory response in patients with advanced disease.
This inflammatory response could also lead to skin rash or red toes observed in some patients. The recent rise in paediatric cases with multisystem inflammatory syndrome (similar to Kawasaki disease) could also be due to an excessive immune response against the coronavirus. However, it is important to point out that these cases are rare.
The WHO has estimated an incubation period (between infection and symptom onset) of 2 to 14 days, although most people develop symptoms between 5 and 7 days.
How lethal is it?
The fatality rate of the new coronavirus was one of the big unknowns of this pandemic. This is due to the fact that SARS-CoV-2 infection causes a wide range of symptom severity: from lack of symptoms to mild and severe disease, pneumonia, and death. According to an analysis of all 72,342 cases diagnosed in China as of February 11, the disease is mild for 81% of patients, 14% develop severe symptoms, and around 4-5% are critical. More recent data, pooled from 14 European countries, indicate that around 40% of confirmed cases have been hospitalised and 2% of these require critical care.
The great majority of deaths occur in people over 65 years of age and/or with an underlying chronic condition or disease. Major risk factors for severe illness and death include hypertension, diabetes, cardiovascular disease and obesity. Men are more vulnerable to disease then women. In contrast, children are considerably less susceptible to developing the disease, although they do seem to get infected. Their role in spreading the virus remains to be determined.
Initial data suggested a case fatality rate (CFR) of around 2% (which means 2 deaths out of every 100 confirmed cases), but these first estimates did not include asymptomatic or undiagnosed cases. A more recent study estimates that the adjusted case fatality rate in China was 1.4% for confirmed cases and 0.66% when considering infected but undiagnosed cases. Another study based on data from Italy estimates that the lethality rate in Lombardy was of 0.84 for every 100 infected cases.
First results in Spain: The first results of the national seroprevalence study indicate that, between January and beginnings of May, around 5% of the country’s population was infected by the virus. This means that the infection fatality rate in Spain was around 1% (one death for every 100 infected people).
As the pandemic advances, it is clear that the reported fatality rate varies between countries (roughly, between 1 and 10% of confirmed cases), and that this depends on the number of diagnosed individuals and other factors such as the percentage of vulnerable people (elderly or with chronic conditions) and the capacity of health systems.
In any case, the case fatality rate of COVID-19 is lower than that of SARS (10%) and could be up to ten times higher than that of seasonal flu (below 0.1%).
5. How is COVID-19 Treated?
To gain time, the medical community started testing drugs that already existed in the market and that could have an effect on the new virus. Some examples are the antiviral drug remdesivir (originally tested for Ebola virus) and an HIV treatment (lopinavir / ritonavir), as well as chloroquine, an old antimalarial drug. Drugs that can modulate the immune system, such as antibodies against interleukin 6, have been tested with encouraging results. This is because, in patients with severe disease, tissue damage not only results from the virus itself, but from an excess of inflammatory molecules (the so-called cytokine storm).
The repurposed drugs that for the moment have been shown to have an effect in controlled clinical trials are remdesivir (it shortens the number of days spent in intensive care) and steroids (dexamethasone reduces mortality among critically ill patients).
SARS-CoV-2 specific drugs have also been developed. Namely, cocktails of monoclonal antibodies have shown to be effective in limiting disease progression when administered early.
The basic preventive measures to avoid infection are: wash your hands frequently, cover your mouth when sneezing or coughing and use a face mask. . It is important to avoid crowds in closed and badly ventilated spaces.
Areas with high viral transmission have adopted stricter social distancing measures, such as cancelling mass gatherings, promoting telework, avoiding unnecessary travel, and keeping a distance of at least 1 meter with other people, among others. These measures, together with the use of face masks, are helping to slow viral spread within the community and avoid overwhelming health systems.
There are over 150 vaccine candidates in development, of which more than 90 have entered clinical trials in humans. Several have already announced preliminary or final efficacy results and eight have been approved for use in the general population (4 of them in Europe).
6. Evolution of the Epidemic
Last update: 07/05/2021 at 3.23 PM. Data from Johns Hopkins University & Medicine.
Source: Our World in Data map with data from Johns Hopkins University.
[This text has been published as a comment in EClinical Medicine ( The Lancet group) by the Lancet Commission on COVID-19 Vaccines...Immunization, Coronavirus, Emerging Viruses 03.06.2021
Rafael Vilasanjuan: “Supporting the temporary suspension of patents is an unprecedented decision for an unprecedented crisis”
On Wednesday, 5 May 2021, the United States announced its support for a proposal at the World Trade Organisation to temporarily waive...Immunization, Coronavirus, Emerging Viruses 06.05.2021
[By Juan Carlos Gabaldón , Medical Research Fellow at the University of Navarra (UNAV), and Carlos Chaccour , Assistant Research Professor and...Malaria, Coronavirus, Emerging Viruses 04.05.2021
Elimination, Not Mitigation, of COVID-19 Yields Best Outcomes for Health, Economy and Civil Liberties
While countries such as New Zealand, Japan and Australia have chosen to fight COVID-19 by adopting an elimination strategy —i.e. maximum...Coronavirus, Emerging Viruses 29.04.2021
New COVID Variants Have Changed the Game, and Vaccines Will Not Be Enough. We Need Global ‘Maximum Suppression’
At the end of 2020, there was a strong hope that high levels of vaccination would see humanity finally gain the upper hand over SARS-CoV-2 , the...Coronavirus, Emerging Viruses 19.04.2021
The “ One Health ” concept, introduced in early 2000, refers to a notion that has been understood for more than a century: human...Antibiotic Resistance, Coronavirus, Emerging Viruses 06.04.2021
You read it right here just the other day: " Three out of four newly described diseases in humans have a zoonotic origin ". Over the past few...Environmental Health, Coronavirus, Emerging Viruses 05.04.2021
[ This article was originally published in Spanish in La Vanguardia. ] I have been listening (with mild irritation) to numerous national...Tuberculosis, Emerging Viruses 24.03.2021
One morning, a 2-year-old boy from a small village in Guinea, where large amounts of the rainforest has been destroyed due to logging and...Environmental Health, Ebola, Coronavirus, Emerging Viruses 17.02.2021
The frantic race to develop COVID-19 vaccines has been the greatest global scientific and economic effort in history . Research centres,...Maternal, Infant and Reproductive Health, Immunization, Coronavirus, Emerging Viruses 28.01.2021
This article was originally published in Catalan in Espai Salut , a bulletin published by the Diputació de Barcelona There is a ...Environmental Health, Coronavirus, Emerging Viruses 27.01.2021
[Author: Oriana Ramírez , with contributions from Jill Litt , Ximena Goldberg and Adela Briansó ] Mental health ...Environmental Health, Coronavirus, Emerging Viruses 14.01.2021
In recent decades and centuries, humanity’s health and well-being have improved across the globe. Among much else, we have witnessed a...Environmental Health, Coronavirus, Emerging Viruses 16.12.2020
[This article has been originally published in Catalan in 'Espai Salut' newsletter of Diputació de Barcelona] [Authors:...Environmental Health, Coronavirus, Emerging Viruses 04.12.2020
Payam Dadvand: "The Pandemic Shows How Active Mobility, Better Air Quality and Green Spaces could Reduce the Risk of Disease Transmission and Mitigate its Consequences"
We talked with Payam Dadvand , coordinator of Global Environmental Health course and Associate Research Professor at...Environmental Health, Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 20.11.2020
[This article has been originally published in Spanish in Planeta Futuro-El País] When, 300 international experts in the...Health Equity, Coronavirus, Emerging Viruses 12.11.2020
World Cities Day 2020 The COVID-19 pandemic is a wake-up call . Our world will never be the same again and neither will be our...Environmental Health, Coronavirus, Emerging Viruses 29.10.2020
[Authors: Natalia Rakislova and Adelaida Sarukhan (ISGlobal)] Just nine months after the first cases were reported in...Coronavirus, Emerging Viruses 16.10.2020
Climatological, meteorological and environmental conditions are not the main causes of the first wave of the COVID-19 pandemic. However, questions...Environmental Health, Coronavirus, Emerging Viruses 07.10.2020
[This article has been originally published in Catalan in 'Espai Salut' newsletter of Diputació de Barcelona] “Stay...Environmental Health, Coronavirus, Emerging Viruses 23.09.2020
[Authors: Raül Toran, Marina Tarrús and Celia Santos, members of ISGlobal’s Scientific Culture and Innovation Unit] A Planet of...Epidemiology, Emerging Viruses 02.09.2020
Stay informed on the COVID-19 scientific updates and other global health issues. Click here to sign up for email updates from ISGlobal. ...Coronavirus, Emerging Viruses 18.08.2020
[Authors: Uxue Alfonso Viguria , Global Health student at University of Geneva and Marta Ribes Agost , ISGlobal-UB...Coronavirus, Emerging Viruses 11.08.2020
On any given summer evening, it is not unusual to find 500 people milling about in Plaça Espanyola , the nerve centre of the La Torrassa...Coronavirus, Emerging Viruses 29.07.2020
The COVID-19 pandemic has affected the way we approach the teaching and learning experience in our master’s programmes at an...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 15.07.2020
We are living a health crisis with enormous consequences. Reducing the transmission (risk) of COVID19 is extremely important. Prevention measures...Coronavirus, Emerging Viruses 13.07.2020
How Has the COVID-19 Crisis Affected Mental Health and Physical Activity? Participate in the ACTIVID Project
[Authors: Guillem Vich and Mònica Ubalde, members of Urban Planning, Environment and Health Initiative at ISGlobal ] In response to the...Environmental Health, Coronavirus, Emerging Viruses 07.07.2020
[This text has been written by Juliane Chaccour , immunologist and medical editor; Marta Valente , pediatrician at the Centro de...Coronavirus, Emerging Viruses 02.07.2020
The term necropolitics was coined by Professor Achille Mbembe of South Africa’s University of the Witwatersrand. In his 2003...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 17.06.2020
Global Health Students Tackle COVID-19 Head-On: From Classroom to First-Hand Experience in a Seroprevalence Study
COVID-19 has been a life-changing experience for students in the ISGlobal–University of Barcelona Master of Global Health and Master...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 16.06.2020
Limitations and Strengths of the First Clinical Trial of Hydroxychloroquine to Prevent COVID-19 Disease
[Authors: Clara Pons y Elena Marbán , predoctoral researchers at ISGlobal] In recent weeks, hydroxychloroquine (HCQ) ...Coronavirus, Emerging Viruses 12.06.2020
Can cities make quick fixes to slow the spread of COVID-19? Could these changes also help to improve our overall health and well-being? Low-cost,...Environmental Health, Coronavirus, Emerging Viruses 10.06.2020
[This text has been written by: Adelaida Sarukhan , scientific writer at ISGlobal, and Rafa Vilasanjuan , Policy and Global...Coronavirus, Emerging Viruses 04.06.2020
Without Rigor and Transparency, There Can Be no Science: about Surgisphere and its Scientific Publications in High Impact Journals
[This text has been written by: Alberto García-Basteiro , Assistant Research Professor at ISGlobal and physician at the International Health...Emerging Viruses 03.06.2020
While mental health is a central pillar of a well-rounded approach on global health policy formulation, it appears to be something that is not...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 02.06.2020
Ivermectin and COVID-19: How a Flawed Database Shaped the Pandemic Response of Several Latin-American Countries
[Authors: Carlos Chaccour , Assistant Research Professor at ISGlobal and BOHEMIA Chief Scientific Officer; Joe...Malaria, Coronavirus, Emerging Viruses 29.05.2020
BiSC Project and COVID-19: Assessing the Impact of Air Pollution on Pregnant Women During the Pandemic
[Authors: Paula de Prado Bert, Laura Gómez Herrera and Jordi Sunyer. BiSC Project, ISGlobal] In recent weeks, we have all been...Environmental Health, Coronavirus, Emerging Viruses 13.05.2020
[This post has been written by Camila Picchio , Research Assistant, and Jeffrey V. Lazarus , Associate Professor and head of the...Health Equity, Coronavirus, Emerging Viruses 07.05.2020
We have heard it so many times in recent weeks that by now it seems obvious: we will not finally overcome this crisis caused by COVID-19 until we...Immunization, Policy & Global Development, Coronavirus, Emerging Viruses 30.04.2020
This article has been written by Jose Luis Jimenez , Professor at Colorado University-Boulder; Jordi Sunyer...Environmental Health, Coronavirus, Emerging Viruses 29.04.2020
Disease outbreaks affect men and women differently. Early studies suggest that the SARS-CoV-2 virus may be killing more men than women....Maternal, Infant and Reproductive Health, Health Equity, Coronavirus, Emerging Viruses 27.04.2020
Denise Naniche: “COVID-19 Illustrates the High Level of Interdependence that Connects People All Over the World”
We talk with Denise Naniche , coordinator of " Development and Application of Vaccines in Global Health " course. She was...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 23.04.2020
COVID-19 interventions and research projects are being developed at unprecedented speed. Some of our ISGlobal alumni have the opportunity to show...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 17.04.2020
I would never have imagined finding myself working as a clinical nurse in the most affected Italian city during the COVID-19 epidemic . I was...Training & Education, ISGlobal Alumni, Coronavirus, Emerging Viruses 17.04.2020
Photo: Glen Carrie on Unsplash According to the Spanish Paediatrics Association (AEP), the recommended minimum amount of ...Coronavirus, Emerging Viruses 09.04.2020
During the last weeks, the fight against COVID-19 has become the highest priority of more than 200 countries and territories affected by the...Environmental Health, Coronavirus, Emerging Viruses 06.04.2020
Photo: An empty street due to social distancing measures in Leeds, UK. Dan Burton on Unsplash. This article has been written...Environmental Health, Coronavirus, Emerging Viruses 03.04.2020
Over the last weeks, confirmed cases and deaths from COVID-19 have soared globally, with these figures expected to continue increasing for some...Environmental Health, Coronavirus, Emerging Viruses 25.03.2020
[This article has been written by Carlos Chaccour and Adelaida Sarukhan, in collaboration with Joe Brew and Pau Rubio] Over the last weeks, ...Coronavirus, Emerging Viruses 17.03.2020
The risk is that the efforts undertaken by Europe, USA and other developed nations will be limited to themselves. It would be foolish to face a...Coronavirus, Emerging Viruses 16.03.2020
In the middle of the 19th century, the General Hospital in Vienna had two maternity clinics with very different outcomes in terms of mortality: ...Communications, Emerging Viruses 30.04.2019
The Ebola outbreak in DRC, the wildfires in California, the first high-level meeting on tuberculosis and the #Metoo movement were some of the...Communications, Emerging Viruses 19.12.2018
Interview with Dawoh Peter Lansana (better known as Brother Peter), director of the Saint Joseph’s Catholic Hospital of Monvrovia, Liberia,...Ebola, Emerging Viruses 05.12.2018
[This article has been published in Spanish in Planeta Futuro-El País] The global health community is still working on addressing and...Ebola, Emerging Viruses 14.05.2018
[Written for Big Vang (La Vanguardia) by Adelaida Sarukhan , PhD in immunology and scientific writer at ISGlobal, Jose Muñoz , ISGlobal...Epidemiology, Immunization, Emerging Viruses 17.03.2018
Vector-borne diseases make up 17% of all infectious diseases worldwide , causing 700,000 deaths every year and around 250,000 if we exclude...Malaria, Zika, Emerging Viruses 15.09.2017
In a recent study, we used climate forecasts to predict the risk of a dengue epidemic Decision-makers in resource strained settings face...Environmental Health, Emerging Viruses 10.07.2017
[This article has been written by Adelaida Sarukhan , PhD in Immunology scientific writter at ISGlobal, and Joaquim Gascon , Head of...Epidemiology, Emerging Viruses 05.09.2016
They are the most beautiful mosquito species we have: The Aedes family . Small, dark with bright white spots and stripes. But that is only...Zika, Emerging Viruses 17.08.2016
[This article is written by Adelaida Sarukhan (ISGlobal) and Jose Muñoz (ISGlobal-Hospital Clínic) and it has been published in Spanish...Zika, Emerging Viruses 01.06.2016
The Ebola epidemic in West Africa was declared a public health emergency of international concern by the WHO in August 2014. Since then ,...Ebola, Emerging Viruses 21.03.2016
The recent declaration of the zika virus as a “global emergency” by the WHO as a consequence of the epidemic in Latin America...Epidemiology, Emerging Viruses 09.02.2016