People sick with covid infect others for a while. Nobody knows exactly how long the virus is shedding. It is known for sure that even before the first symptoms, people become infectious, then they get sick and the amount of the virus gradually decreases.
If we are talking about a strong person with decent immunity, who was not too sick and did not get to the hospital, then somewhere after 7 to 10 days from the onset of the disease, he no longer infects anyone.
And then a sick person begins to do smears. This is PCR that easily detects the virus itself. That is, the smear does not look for antibodies, but literally catches the animals.
If a person is already old, and the disease torments him greatly, then the virus will be secreted for a long time. It will stand out both with snot and with intestinal contents, but how exactly it will infect people around it has not yet been calculated.
The Italians checked their patients, and it turned out that on average, the virus is released for 30 days, and if you look well, then, probably, it can stand out for several months.
This is bad? No it is OK. If a person secretes a virus, this does not mean that he will infect someone.
To get infected with covid, you need a so-called infectious dose. Let's say conditionally that it is necessary to inject ten thousand evil viruses into the nose of an experimental person in order for him to get sick. If you inject four of the virus, the person will not get sick.
This is not the kind of virus that alone can sabotage. Our covid needs a whole army to attack.
There is also such a trick that if a person picks up a few viruses, then it will not be too hard to get sick. Therefore, scientists decided to count the viruses. It turned out that at the height of the disease, about seven hundred million viruses were picked out on the stick that was shoved into the nose to obtain a smear. It is clear that these people get sick and infect others.
Then the scientists calculated the safe amount of the infection, and it turned out that about one million viruses per milliliter of the patient's snot can no longer infect an outsider.
So listen to your doctor and take as many strokes as he says. Everything in this business is changing rapidly, but there is a strict bureaucracy.
