Covid-19 can cause a diverse range of symptoms, affecting multiple body systems.Different people are affected in different ways: these varied manifestations have made it tricky to isolate cases and understand the underlying pathology. Importantly, some people may have no symptoms at all (asymptomatic) but can still spread the virus. There have been wide variations in the estimate for the proportion of covid-19 carriers who are infected- understanding this is really important to reduce transmission.
Initially, we were told the main symptoms to look out for (and take action by self-isolating) were a fever and cough, but it has become clear that there are very many other manifestations of covid-19. This is reflected in the updated symptom list that various health authorities use.
In the UK, the current general clinical case definition (what symptoms constitute a likely diagnosis of covid-19) includes: New continuous cough OR fever OR loss of/ change in smell or taste.
However, it has become clear that covid-19 doesn’t just attack the lungs. There are many other symptoms that infected people may experience: musculoskeletal, neurological (loss of smell, taste, tingling, seizures), gastrointestinal (loss of appetite, abdominal pain, nausea, vomiting, diarrhoea), haematological (e.g. clots in lungs and causing strokes) and even skin symptoms.
The WHO lists the following symptoms:
Most common symptoms:
- dry cough.
Less common symptoms:
- aches and pains.
- sore throat.
- loss of taste or smell.
- a rash on skin, or discolouration of fingers or toes.
- difficulty breathing or shortness of breath.
- chest pain or pressure.
- loss of speech or movement.
As you can see, there is a wide variety of symptoms of covid-19. It can be a great imitator: all of these symptoms could represent other illnesses and must be differentiated from these.
Doctors and scientists are trying to understand how the virus causes this vast range of different symptoms, targeting multiple body systems. This should help to elucidate the pathology of the disease and highlight potential targets for therapy.
Time course of symptoms
The average time from exposure to symptom onset (known as the incubation period) is about five to six days. However, studies have shown that symptoms could appear as soon as three days after exposure to as long as 13 days later. This supports the guidance for quarantine for 14 days post exposure. It is well known that people can be infectious before symptoms start (pre-symptomatic spread).
The pattern and time course of symptoms varies amongst individuals. Some people can have mild symptoms for about a week and then get worse. If this happens, it is very important to seek help as symptoms can rapidly worsen. Sometimes the oxygen levels of a patient are very low but they may not be aware of this or feel too breathless (so-called “silent hypoxia”). This is why it is useful to have an oxygen saturation probe (also known as pulse oximeter) at home, which measures your oxygen levels when put on your finger. This is helpful when talking to a health professional on the phone as these levels can help as part of the triage process.
As more people have been infected and recover, it is also becoming apparent that the effects of illness can linger with long-term repercussions. Covid-19 may trigger a post-viral fatigue syndrome in some patients.
Covid-19 in children
Evidence from across the globe (namely China, Spain, Italy and America), has shown that children are significantly less affected by COVID19 than adults. There are both fewer cases in children, and less children who are severely unwell. In children, the symptoms are more likely to be mild and a significant proportion may be asymptomatic. The most common symptoms are fever and cough. Around 10% have gastrointestinal symptoms (vomiting, diarrhoea).However, in the last two months, a small number of children have been identified who develop a significant systemic inflammatory response. This has been named Paediatric Multisystem Inflammatory Syndrome – Temporally Associated with SARS-CoV-2. It is an extremely uncommon disease entity and the vast majority of children, including those who were critically ill, have made a good recovery. You can read more about it here.