As a privacy advocate, I generally advocate for opt-in as opposed to opt-out policies. But here’s a report from the medical field that shows the potential benefits of opt-out. Micheal Carter of aidsmap reports:
Implementing a policy of routine opt-out HIV testing led to the diagnosis of 3000 HIV infections in children admitted to hospital in Lusaka over an 18-month period, investigators report in a study published in the online edition of the Journal of Acquired Immune Deficiency Syndromes.
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In an attempt to increase the number of diagnosed HIV-positive children in Lusaka, Zambia, investigators at the University Teaching Hospital implemented a policy of offering routine HIV counselling and testing to all children admitted as inpatients.