Analysis of Efflcency to Screening of IgG Antibodies Anti-HVA Previous the Active or Passive Inmunization

Abstract

Bockgmund: The epidemiological patmn of hepatitis A has changed in the last few years and B decrease of the anti-hepatitis A antibodies IgG (Anti-HVA) have been observed at early ages, which will accompany in the future an increase of symptomatic hepatitis. The prevention of hepatitis A requires a strict application of the norms of personal and environmental hygiene and the administration of vaccines or inmunoglobulins. In order to determine the convenience of inmunization actively or passively with or without the previous detection of Anti-HVA, requires the knowledge of with strategy is more efficient. Methods: An analysis is carriout to determine the thershold of prevalence, where the reason of effciency is estabtished by compating the unit cost of inmunization either activeiy or passively of the population, with a cost of inmunizing only the negative Anti-HVA by previous screening, with the formula: the unit cost of the active or passive inmunization (unit cost of screening + cost of active or passive (inespecific inmunoglobuiine) inmunization in the negative Anti-HVA). The resuls correlate with the prevalence of Anti-HVA in age group founded in sero-epidemiological studies publied by Sallems (1992 and Pérez-Trallero (1994). Results: The threshold of prevalence, the reason of efficciency equals 1, it‘s situated in 18% and 65% respectivelly for the active and passive inmunization, which corresponds to the age group of lo-19 years and 20-29 years based on ser-o-epidemiological studies used. Conclusions: With prevalence of Anti-HVA equal to oí above 18% of the population the most efficient strategy is to determine the Anti-HVA before the active inmunization; This threshold of prevalence move to up to 65% with passive inmunization. Beneath these prevalence it‘s more efficient to inmunize actively or passively without prior screening.