An asymptomatic or mild course of the disease most often indicates a low dose of infection. Experts-immunologists expressed this opinion in an interview with the correspondent of the newspaper "Gazeta.ru".
In the absence of symptoms of the disease, immunity does not develop a response, said infectious disease doctor Anna Balandina. In addition, it is not uncommon for the level of antibodies in the human body to be so low that the test system cannot determine their presence.
The development of cellular immunity is much more important than that which is formed after the production of antibodies. Its formation involves macrophages - cells that can actively capture and digest bacteria. They are the first to fight the virus at the level of innate immunity, long before antibodies are formed, says immunologist Elena Churina.
“The cells protect the body from the pathogen. They do not understand whether he is good or bad, but immediately begin to attack. Then they take a fragment of the infection and transfer it to the lymph nodes to make antibodies,”she explained.
Initially, antibodies are produced in the human body. However, their number is so low that by the time of analysis they manage to decrease to zero, said immunologist Tatiana Shalina. In this case, "memory cells" can work in the body. They help a certain segment of the population to maintain immunity.