The mechanism of CD4 T cell depletion, although apoptosis may also be a factor.

The World Health Organization recommends treating all children less than 5 years of age; children above 5 are treated like adults.

Measures to prevent opportunistic infections are effective in many people with HIV/AIDS.

The most effective vaccine trial to date, RV 144, was published in 2009 and found a partial reduction in the risk of transmission of roughly 30%, stimulating some hope in the research community of developing a truly effective vaccine.

Treatment recommendations for children are somewhat different from those for adults.

The risk of acquiring HIV from a needle stick from an HIV-infected person is estimated as 0.3% (about 1 in 333) per act and the risk following mucous membrane exposure to infected blood as 0.09% (about 1 in 1000) per act.

Preventive treatment involves the mother taking antiretrovirals during pregnancy and delivery, an elective caesarean section, avoiding breastfeeding, and administering antiretroviral drugs to the newborn.

Because of its relatively poor capacity for transmission, HIV-2 is largely confined to West Africa.

After the virus enters the body there is a period of rapid viral replication, leading to an abundance of virus in the peripheral blood.

and is the cause of the majority of HIV infections globally.