Every virus is a parasite that cannot exist on its own and is fully dependent on its carrier. This is the basic condition of its existence. The host of viruses is a living cell. Based on many years work with BLV in stables, I came to the conclusion that the carrier of the virus is a bacterial cell. This idea was subsequently tested in a model of HIV, where it was also shown that both bacteria and yeast in the intestinal tract can be its hosts. Similarly, we monitored the presence of the new coronavirus in the intestinal tract of the infected. Rectal swabs were taken from patients who overcame infection with the new coronavirus four weeks ago. The results show that in the majority of patients (83%) the virus is still present in their intestinal tract and can cause a de novo infection in the patient and infect others. Based on these results, it was concluded that many, if not all, viruses can be transmitted by bacteria, yeast. After overcoming viral infection, a part of the virus in most infected people passes into the intestinal tract hidden in carriers. This is indicated by the increasing number of new variants of the novel coronavirus, and the high infectivity detected in wastewater around the world proves that the coronavirus is in the tract long after the epidemic is over. By identifying the carrier and its elimination, we will also destroy the virus. The viral load localized in the intestinal tract is under the control of the immune system. Vaccines are ineffective in the intestinal tract.