The saliva test for COVID-19 is itself suspect - it only works if there is sufficient virus in the saliva to register -a blood test would be far more accurate, but that is more invasive and it takes longer to get the result at additional cost. Reason I am highlighting this is the Japanese experience:
"...
Japan's health minister says dozens of passengers who were allowed off a coronavirus-stricken cruise ship have developed symptoms - including fever - and will be asked to take tests for the virus.
The government has contacted 813 former passengers of the Diamond Princess. Around 970 were allowed off the boat last week after testing negative for the virus, but several have subsequently been found to be carrying the disease.
..."
So people let out of quarantine on the basis that they were virus free, when clearly a substantial proportion were not. Three new cases reported from Thailand today are all people who recently visited Japan. Point is that the authorities may feel they have the situation under control, when they haven't, both because of asymptomatic cases and because the saliva test itself produces false negatives.
Originally Posted by: Maunder Minimum