The dangers of relying upon screening

It is sometimes suggested that the screening of patients in hospitals, the screening of healthcare workers, or the adoption of barrier precautions only against those identified either as HIV-positive or as identifiable members of risk groups, will prevent further cases of HIV infection. This is a fallacy for several reasons:

  • It is impossible to identify everyone who is HIV-infected by HIV testing because of the 'window period' between infection and the appearance of antibodies.
  • It is impossible to identify everyone who is HIV-infected on the basis either of questions about past behaviour or presumed membership of a 'risk group'.
  • It is impossible to judge the need for universal precautions on the basis of historical, retrospective knowledge about HIV prevalence in a particular area.