Monocytes and NK Cells Activity in Covid-19 Patients

SARS-CoV-2 belong to beta-coronavirus family and its transmission route and symptoms follow those of all community-acquired coronaviruses. The main difference of the novel Coronavirus is the higher mortality rate, that is around 3%. Death rate is over 1% only for patients over 50 years old, whereas until 40 years old is under 0,4%. No fatalities are declared among children under 10 years old to date. Death rate is almost double for male rather than female. This distribution of mortality rate according to age of infected patients could be only partially ascribed to other comorbidities in addition to great age. In fact, patients with no pre-existing conditions have however a case fatality rate of 0,9%. The almost null rate of severe illness in children and generally in patients younger than 40 years old is quite un-explicable. Infant, children and young people could be infected but infection is rapidly self-limited or without symptoms. Older patients undergo severe lung injury as consequence of an immune response that is late in coming. Possible explanation of these phenomena could be something, which assure ability to prompt response to SARS-CoV-2 in younger people independently from the novelty of the virus itself. It would seem to be that younger people are already sensitized to the antigens of the virus without a previous contact. This immunity is not really specific, but "partially specific" for many antigens of the virus, however able to limit the infection in the organism. Something stimulated the immune system and it scattered immunity against more and more antigens present. Children are the age group mostly exposed to all community-circulating viruses. This immunity is not persistent but progressively fade out. It protects from the age of two, when the hypothetical stimulation occurs, to the fifth decade because of its slow decrease. The only external stimulation, which healthy people receive are vaccines. All vaccinations and especially tetanic, dipht