severe pneumonia (PCP or pneumocystosis) occur in people living with HIV (PLHIV) with CD4+ T cells counts < 200/mm3, and the incidence in Western Europe and the United States is < 1 case per 100 person-year [62] In Portugal, in the year 2022, in 138 cases of AIDS, PCP was the first opportunistic infection, diagnosed in 26.8% of the cases [63]. This evidence concerns the gene CD4 and pneumocystosis.