Essential Facts and Figures – COVID-19

This page aims to summarise our understanding of the current science on key questions about COVID-19 (as of 3 April, 2020), as best we can given the state of the evidence and the fast moving situation. We provide more explanation as well as sources in the footnotes.
Symptoms and severity
- The most common reported symptoms are cough (appearing in about 80% of confirmed cases – meaning those who have been tested and found to be infected with the virus) and fever (80%-90%). Many also experience shortness of breath, usually later in the disease progression. Diarrhea and other GI symptoms have also been seen in some patients. Nasal congestion and runny nose seem uncommon (<5%). Anecdotally, loss of the sense of taste or smell have also been reported.
- Once someone is infected, it seems to typically take ~7 days for symptoms to develop. One study with a large sample size found that for 11.5% of confirmed cases it took more than 14 days.
- According to initial data from China, around 81% of confirmed cases are ‘mild’ (though can still involve pneumonia), 14% are severe (requiring hospitalisation), and 5% are critical. A large proportion of people infected with the virus have mild symptoms, and around 20% may have no symptoms, though there is not reliable data here.
- Most current estimates of the fraction of infected people (rather than people with confirmed cases) who die from the disease (the ‘IFR’) seem to be between 0.1% and 2%.


















