As the pandemic spreads, more and more people go through the coronavirus. So, more people ask themselves questions: Am I no longer ill? Am I no longer contagious for others?
It was investigated that the ill person is the most contagious in the beginning of the illness, when symptoms are only starting to appear. Then the contagiousness is steadily decreasing during the next 21(!) days.
We don’t know much about COVID-19 yet and, unfortunately, the coronavirus doesn’t give simple “yes” or “no” answers. For example, if you have no symptoms and tests reveal IgG antibodies, you are unlikely to be contagious. Unfortunately, only “unlikely”, because there were cases when people continued spreading coronaviruses up to 42 days(!) after all decease symptoms disappeared.
So, it seems like the best way to get to know that you are no longer contagious if the PCR test. And since there is a substantial share of false-negative results, it may be a good idea to take the test twice.
Because of this not complete reliability it makes sence to use all those well-known rules: to keep distance from other people, wear masks in public places and regularly wash your hands.