All antiviral drugs have the same principle of action. They replace or stimulate the production of interferons that prevent the introduction of the virus into cells - thequestion.ru
Their effectiveness against different viruses may differ purely formally. For example, the drug was tested on the flu virus or, conversely, herpes, and the effectiveness with rotavirus has not been studied. Or the drugs induce specific interferons that are active against a certain group of viruses.
I am, of course, touched by statements about medical workers that effective antiviral drugs are only for the flu.
I bring to your attention that there are also antiviral drugs in nature with proven efficacy against herpes (acyclovir , Valacyclovir), hepatitis (entecavir, ribaverin, lamivudine), etc.
As for the time of administration, the most effective anti-influenza Oseltamivir is effective in the first 2 days after the onset of symptoms.
hepatitis B is used in the midst of a chronic disease (although a person will not notice this very peak without periodic examinations).
I will not say about the rest, because I have not encountered it personally.
If we are talking about an acute respiratory viral infection, then there are no drugs with proven efficacy and safety. And taking them at the beginning, middle or end of the disease is a rather pointless exercise. For example, read what the American Academy of Family Physicians recommends - familydoctor.org Antivirals are only available for the flu and should be taken early in the illness. There is nothing that is advertised in Russia as antiviral drugs, there is no "Arbidol" there. If it proved to be effective, it would be sold on every corner in the West, since the financial losses due to cold workers are quite large.