Some further research on asymptomatic cases.
In Nanjing 24 asymptomatic individuals who tested positive to Covid-19 and who had no underlying health concerns were followed. 17 went on to develop symptoms and the average age of those who remained asymptomatic was 14, suggesting the possibility of a viral reservoir among asymptomatic children. They remained RT-PCR positive for 9.5-21 days.
On the Diamond Princess 17.9% of the people who tested positive were asymptomatically infected, although these individuals were not clearly followed long enough to see whether they should be more appropriately described as presymptomatic.
A patient who travelled home from wuhan and tested positive 19 days after contact with someone who was asymptomatic, all the other travellers on the bus who subsequently tested positive went on to develop symptoms.
55 people in Shenzen who were asymptomatic and identified as family members of patients with covid-19 that tested positive for the virus. 29% had abnormal CT scans despite no symptoms, all developed symptoms within 7 days of testing positive with the youngest more likely to have mild symptoms.
36 children (average age 8.3) in Zhejiang whose parents or close contacts had been admitted to hospital for covid-19 were tested and followed up
All where found to be infected.
19 developed moderate pnemonia
10 where asymptomatic,
7 developed actute upper respiratory symptoms.
Although all paediatric patients in our cohort had mild or moderate type of COVID-19, the large proportion of asymptomatic children indicates the difficulty in identifying paediatric patients who do not have clear epidemiological information, leading to a dangerous situation in community-acquired infections.
News article in UK.
A women died of covid-19 and all 17 members of the family who attended the funeral on 13th March have symptoms within 7 days. One further member of the family has died and another is not expected to survive. They are aged 21 to 88.
Overall the key reason I'm posting this is to show why social distancing is so important and that the evidence is you are capable of infecting others days before you are aware you have the virus and even if you never develop symptoms. I'm also highlighting the paucity of evidence to support huge numbers being asymptomatic. In the UK I am very glad that the lockdown came just before mothering sunday and not afterwards as I generally believe it would've been carnage if families had all gone to visit their elderly relatives at this time.