1. Middle-aged and elderly people have no habit of wearing condoms. Usually old people think that they are too old to get pregnant, so it is not necessary to wear condoms.
2. The life expectancy of middle-aged and elderly people is generally prolonged, and the demand for sex is increasing, or the elderly will have multiple sexual partners because of widowhood, thus increasing the risk of AIDS transmission.
3. Middle-aged and elderly people lack common sense to prevent AIDS and cannot be screened regularly.