COVID-19 — SARS-CoV-2

VADS CORNER — Coronavirus Disease 2019 · Severe Acute Respiratory Syndrome Coronavirus 2
Online since January 2020 · Comprehensively revised 9 September 2026

This page covers COVID-19 (coronavirus disease 2019) and its causative agent SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). The page was first posted in January 2020 at the outset of the outbreak that began in Wuhan, China. For information on the earlier Severe Acute Respiratory Syndrome (SARS) outbreak of 2002–2003, see the dedicated page.

Resource sites

• WHO
  • WHO: Coronavirus (COVID-19)
  • Coronavirus disease (COVID-19) advice for the public
  • Situation reports (archive)
  • COVID-19 vaccines — WHO
• Centers for Disease Control and Prevention (CDC)
  • COVID-19 — CDC
  • Symptoms of COVID-19
  • About COVID-19 — symptoms, complications, transmission, prevention and treatment
  • For healthcare professionals
  • Emerging Infectious Diseases — Coronavirus spotlight
  • CDC MMWR, Morbidity and Mortality Weekly Report
    • Presymptomatic transmission of SARS-CoV-2 — Singapore, January–March 2020
• ECDC (European Centre for Disease Prevention and Control)
  • COVID-19 — ECDC FIXED
• COVID-19 — Public Health Agency of Canada
• UK Health Security Agency (UKHSA) FIXED
• COVID-19 — Australian Government Department of Health FIXED
• COVID-19 — Wikipedia FIXED

About SARS-CoV-2 — naming and taxonomy

Official names were announced by WHO and the International Committee on Taxonomy of Viruses (ICTV) in February 2020. The disease is coronavirus disease 2019 (COVID-19); the virus is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

• WHO: Naming the coronavirus disease (COVID-19) and the virus that causes it
• International Committee on Taxonomy of Viruses (ICTV) FIXED
• SARS-CoV-2 — Wikipedia
• SARS-CoV-2 sequences — NCBI Virus FIXED
• Nextstrain: SARS-CoV-2 genomic epidemiology FIXED
• Nextstrain: global 6-month open data view NEW
• GISAID — global initiative on sharing all influenza data (includes SARS-CoV-2)

Virology background

• Nature: updates on the respiratory illness caused by a novel coronavirus (January 2020)
• COVID-19: genetic network analysis provides snapshot of pandemic origins — University of Cambridge (12 April 2020)
  • PNAS article
• The coronavirus did not escape from a lab. Here’s how we know. — LiveScience
• Coronavirus origins: genome analysis suggests two viruses may have combined — World Economic Forum

Symptoms and clinical presentation

Source: CDC COVID-19 Signs and Symptoms

Symptoms may appear 2–14 days after exposure and range from mild to severe illness. The following list is not exhaustive; symptoms may change with new variants and can vary with vaccination status.

• Fever or chills
• Cough
• Shortness of breath or difficulty breathing
• Sore throat
• Congestion or runny nose
• New loss of taste or smell
• Fatigue
• Muscle or body aches
• Headache
• Nausea or vomiting
• Diarrhoea

• AAO-HNS: Anosmia, hyposmia, and dysgeusia as symptoms of coronavirus disease (22 March 2020)
• How does coronavirus kill? Clinicians trace a ferocious rampage through the body, from brain to toes — Science (17 April 2020)

COVID-19 vaccines

• COVID-19 vaccines — CDC FIXED
  • Staying up to date with COVID-19 vaccines FIXED
• COVID-19 vaccines — WHO
• COVID-19 vaccine — Wikipedia
• Reuters: Vaccine bootcamp — types of COVID-19 vaccines and how immunity develops
• Why you can’t compare COVID-19 vaccines — YouTube

Key vaccine studies

• Effectiveness of COVID-19 vaccines against the B.1.617.2 (Delta) variant — NEJM
• Heterologous ChAdOx1 nCoV-19 and mRNA-1273 vaccination — NEJM
• Pan-sarbecovirus neutralising antibodies in BNT162b2-immunised SARS-CoV-1 survivors — NEJM
• Efficacy of inactivated SARS-CoV-2 vaccines against the Delta variant — Guangzhou real-world study

Outbreak data and trackers

Most real-time dashboards launched in 2020 are no longer actively maintained. Current aggregate data are best accessed through Our World in Data and the WHO situation reports archive.

• Our World in Data: COVID-19 FIXED
• Worldometers: Coronavirus — cumulative global statistics
  • Transmission rate (R₀)
  • Coronavirus death rate
• COVID-19 pandemic preparedness — International SOS
• COVID Tracking Project (USA) ARCHIVE Data collection ended March 2021; archive remains accessible.

Useful articles and publications

Dated entries below are from the acute phase of the pandemic (2020–2021) and are retained as a historical record. Links checked 9 September 2026; those confirmed dead are marked accordingly.

Clinical guidance and treatment

• The Internet Book of Critical Care — COVID-19 Comprehensive resource for health professionals.
• Brigham and Women’s Hospital COVID-19 Critical Care Clinical Guidelines (25 March 2020)
• Pharmacologic treatments for coronavirus disease 2019 (COVID-19): a review — JAMA (19 April 2020)
• Rational use of face masks in the COVID-19 pandemic — The Lancet Respiratory Medicine (29 March 2020)
• COVID-19: up-to-date guidelines, resources, and caregiver communications — Cleveland Clinic (Thanks to Dr David KL Quek)
• Information for clinicians on therapeutic options for COVID-19 patients — CDC (Thanks to Prof Lam Sai Kit)
• Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand — Imperial College London (Thanks to Dr Nimala Sashi)
• Radiology department preparedness for COVID-19: Radiology Scientific Expert Panel (Thanks to Dr Ragupathy) — Article PDF
• SITC statement on access to IL-6-targeting therapies for COVID-19 — Journal for ImmunoTherapy of Cancer (20 April 2020)
• Why ventilators may not be working as well for COVID-19 patients as doctors hoped — Time (16 April 2020)

Local PDFs (hosted on this site)

• Exit strategies for COVID-19: can life return to normal? — Dr Amar-Singh HSS and Dr Lim Swee Im, Malay Mail (30 March 2020)

Epidemiology and public health

• Correlation between universal BCG vaccination policy and reduced COVID-19 morbidity and mortality: an epidemiological study (2 April 2020)
• Coronavirus case counts are meaningless* (*Unless you know something about testing) — FiveThirtyEight (5 April 2020)
• Non-pharmaceutical interventions implemented by US cities during the 1918–1919 influenza pandemic — JAMA
• Pre-emptive low-cost social distancing and enhanced hygiene implemented before local COVID-19 transmission — Craig Dalton et al., SSRN
• Singapore launches contact tracing mobile app to track coronavirus infections — Malay Mail

Other articles worth reading

• How will Delta evolve? Here’s what the theory tells us — The Conversation (23 August 2021)
• Why the coronavirus changed over time, and what it means going forward — STAT News (20 August 2021)
• How we live with the coronavirus forever — The Atlantic (18 August 2021)
• Delta has changed the pandemic endgame — The Atlantic (12 August 2021)
• How the coronavirus infects cells — and why Delta is so dangerous — Nature (28 July 2021)
• Why the coronavirus has been so successful — The Atlantic
• Coronavirus: The Hammer and the Dance — Tomas Pueyo (Thanks to Dr Tan See Kin)
• Coronavirus: Why you must act now — Tomas Pueyo
• Coronavirus infographic datapack — Information is Beautiful
• The tip of the iceberg: virologist David Ho speaks about COVID-19 — Caltech
• Accurate science communication is key in the fight against COVID-19 — World Economic Forum
• A student’s guide to handling post-pandemic back-to-college anxiety — Psychology Degree Guide (Thanks to Amber Bobnar, August 2021)

What can I do from home? (pandemic-era resources)

• Open Culture — free online courses, books, videos, languages (12 April 2020)
• National Emergency Library — Internet Archive (27 March 2020)
• Internet Archive — Wayback Machine

Medical journals and PubMed searches

• 2019-nCoV Resource Centre — The Lancet
• 2019 Novel Coronavirus — NEJM
• JAMA COVID-19 Resource Center
• Annals of Internal Medicine — Coronavirus FIXED
• Emerging Infectious Diseases — peer-reviewed journal
• ScienceDirect: Coronavirus articles
• Elsevier: free health and medical research on novel coronavirus
• Cochrane Library — COVID-19 evidence reviews FIXED

PubMed searches

Source: NLM PubMed. Click “Related articles” on any abstract for further results.

• COVID-19
• SARS-CoV-2
• 2019-nCoV
• Coronavirus
• Severe acute respiratory syndrome

Coronaviridae — background and taxonomy

• Coronavirus — WebMD FIXED
• Coronavirus infections — MedlinePlus
• Coronaviridae — ICTV report FIXED
• Viral evolution, morphology, and classification — Lumen Learning

Respiratory protection

• NIOSH — Respirators
• How to wear a face mask (Thanks to Thomas)
• Coronavirus: why some countries wear face masks and others don’t — BBC (26 March 2020)
• OSHA: COVID-19 FIXED

Worldwide outbreak resources

• Disease outbreak news — WHO
• ProMED-mail — Program for Monitoring Emerging Diseases, Federation of American Scientists

Communicable disease surveillance and other resources

• Centers for Disease Control and Prevention (CDC)
• World Health Organisation (WHO)
• Emerging Infectious Diseases — peer-reviewed journal
• CDC MMWR, Morbidity and Mortality Weekly Report
• Emerging Infectious Diseases Resource Links — CDC
• Epidemiology and Prevention of Vaccine-Preventable Diseases (Pink Book) — CDC FIXED
• The next influenza pandemic: lessons from Hong Kong — Emerging Infectious Diseases, 1999 (Snaacken et al.; relevant background on pandemic preparedness)

Related pages on this site

• SARS — Severe Acute Respiratory Syndrome (2002–2003)
• Paramyxoviridae — Nipah, Hendra and related viruses
• H5N1 Avian Influenza — Bird Flu
• Influenza — further information and links
• Cybermed Archive — Berita MMA
  • Cybermed: Severe Acute Respiratory Syndrome (SARS) — Berita MMA