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]