COVID-19, or Coronavirus Disease, is an infectious disease caused by a virus called Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). COVID-19 mostly spreads through airborne droplets when an infected person coughs, sneezes, speaks or breathes within two metres of others., It’s very infectious, and even those who don’t have symptoms can still spread it.,  The virus enters your body when you breathe in, or if you touch your eyes, nose or mouth with infected droplets on your hands.
Once inside your body, the virus enters your cells and makes new copies of itself. When a person is first infected with a virus, the immune system kicks in and triggers a response to fight the infection. 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., However, SARS-CoV-2 can interfere with the normal immune response in some people and cause it to go into overdrive. It can activate more cytokines than necessary causing what is known as a cytokine storm. This leads the normal response to malfunction, which can be life-threatening.
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. Some people, including but not limited to those with underlying medical problems and older people, may develop a serious illness. Common symptoms of COVID-19 include a fever, dry cough and tiredness. More serious symptoms can include shortness of breath, chest pain and loss of speech or movement.
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. However, as cases began to spread, it was discovered that a novel coronavirus was causing the disease, namely SARS-CoV-2. In March 2020, the WHO announced it as a pandemic.
As of mid-August 2021, there have been over two hundred million cases worldwide of COVID-19 and over four million deaths.
WHO. Coronavirus. Available from: https://www.who.int/health-topics/coronavirus#tab=tab_1. Last accessed: July 2021.
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.
WHO. Listings of WHO’s response to COVID-19. Available: https://www.who.int/news/item/29-06-2020-covidtimeline. Last accessed: July 2021.
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.
WHO. COVID-19 vaccines. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/covid-19.... Last accessed: July 2021.
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.
CDC. Understanding How COVID-19 Vaccines Work. Available from: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/ho.... Last accessed: July 2021.
Zhang JM, An J. Cytokines, inflammation, and pain. Int Anesthesiol Clin. 2007;45(2):27-37.
Fajgenbaum D.C., June C.H. Cytokine Storm. N Engl J Med. 2020; 383:2255-2273.
WHO. Coronavirus. Available from: https://www.who.int/health-topics/coronavirus#tab=tab_3. Last accessed: July 2021.