What became known as Covid-19, or the coronavirus, started in late 2019 as a cluster of pneumonia cases with an unknown cause. The cause of the pneumonia was found to be a new virus – severe acute respiratory syndrome coronavirus 2, or Sars-CoV-2. The illness caused by the virus is Covid-19. Now declared as a pandemic by the World Health Organisation (WHO), the majority of people who contract Covid-19 suffer only mild, cold-like symptoms.WHO says about 80% of people with Covid-19 recover without needing any specialist treatment. Only about one person in six becomes seriously ill “and develops difficulty breathing”.
So how can Covid-19 develop into a more serious illness featuring pneumonia, and what does that do to our lungs and the rest of our body? Wilson says people who catch Covid-19 can be placed into four broad categories.
The least serious are those people who are “sub-clinical” and who have the virus but have no symptoms. Next are those who get an infection in the upper respiratory tract, which, Wilson says, “means a person has a fever and a cough and maybe milder symptoms like headache or conjunctivitis”. He says: “Those people with minor symptoms are still able to transmit the virus but may not be aware of it.” The largest group of those who would be positive for Covid-19, and the people most likely to present to hospitals and surgeries, are those who develop the same flu-like symptoms that would usually keep them off work.