Skip to main content

Search

What is COVID-19?

What is COVID-19?

What is COVID-19?

What is COVID-19?

COVID-19, or Coronavirus Disease, is an infectious disease caused by a virus called Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2).[2] COVID-19 mostly spreads through airborne droplets when an infected person coughs, sneezes, speaks or breathes within two metres of others.[1],[4] It’s very infectious, and even those who don’t have symptoms can still spread it.[4], [5] The virus enters your body when you breathe in, or if you touch your eyes, nose or mouth with infected droplets on your hands.[2]

Once inside your body, the virus enters your cells and makes new copies of itself.[6] When a person is first infected with a virus, the immune system kicks in and triggers a response to fight the infection.[7] It activates several cells including B and T white blood cells, which then triggers other proteins known as cytokines that help fight off the infection.[6],[8] However, SARS-CoV-2 can interfere with the normal immune response in some people and cause it to go into overdrive.[9] It can activate more cytokines than necessary causing what is known as a cytokine storm.[9] This leads the normal response to malfunction, which can be life-threatening.[9]

What are the symptoms of COVID-19?

Most people who get COVID-19 will have mild to moderate cold-like symptoms and will be able to recover by themselves.[1] Some people, including but not limited to those with underlying medical problems and older people, may develop a serious illness.[1] Common symptoms of COVID-19 include a fever, dry cough and tiredness.[11] More serious symptoms can include shortness of breath, chest pain and loss of speech or movement.[10]

When did the COVID-19 pandemic begin?

In December 2019, China informed the World Health Organization (WHO) of a cluster of cases of ‘pneumonia’ in Wuhan.[3] However, as cases began to spread, it was discovered that a novel coronavirus was causing the disease, namely SARS-CoV-2.[3] In March 2020, the WHO announced it as a pandemic.[3]

As of mid-August 2021, there have been over two hundred million cases worldwide of COVID-19 and over four million deaths.[11]

Back to COVID-19

RELATED STORIES

 
 
 
 
 
 
 
 
 
 
References

[1]WHO. Coronavirus. Available from: https://www.who.int/health-topics/coronavirus#tab=tab_1. Last accessed: July 2021.

[2]ECDC. Questions and answers on COVID-19: Basic facts. Available from: https://www.ecdc.europa.eu/en/covid-19/questions-answers/questions-answe.... Last accessed: July 2021.

[3]WHO. Listings of WHO’s response to COVID-19. Available: https://www.who.int/news/item/29-06-2020-covidtimeline. Last accessed: July 2021.

[4]Public Health England. COVID-19: epidemiology, virology and clinical features. Available from: https://www.gov.uk/government/publications/wuhan-novel-coronavirus-backg.... Last accessed: July 2021.

[4]WHO. COVID-19 vaccines. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/covid-19.... Last accessed: July 2021.

[5]Gov.uk. Stay at home: guidance for households with possible or confirmed coronavirus (COVID-19) infection. Available: https://www.gov.uk/government/publications/covid-19-stay-at-home-guidanc.... Last accessed: Aug 2021.

[6]Drexler M; Institute of Medicine (US). What You Need to Know About Infectious Disease. Available from: https://www.ncbi.nlm.nih.gov/books/NBK209710/. Last accessed: July 2021.

[9]CDC. Understanding How COVID-19 Vaccines Work. Available from: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/ho.... Last accessed: July 2021.

[8]Zhang JM, An J. Cytokines, inflammation, and pain. Int Anesthesiol Clin. 2007;45(2):27-37.

[9]Fajgenbaum D.C., June C.H. Cytokine Storm. N Engl J Med. 2020; 383:2255-2273.

[10]WHO. Coronavirus. Available from: https://www.who.int/health-topics/coronavirus#tab=tab_3. Last accessed: July 2021.

[11]WHO. COVID-19 Explorer. Available: https://worldhealthorg.shinyapps.io/covid/. Last accessed: Aug 12 2021.