Varicella screening and vaccination for healthcare workers at KK Women's and Children's Hospital

Varicella is a highly contagious disease with significant morbidity and mortality, especially in adults. It can lead to nosocomial transmission with dire consequences, especially in a healthcare facility where children and pregnant women form the majority of patients. At KK Women's and Children's Hospital, we embarked on a programme in 2 phases, between 1997 and 1999, to screen healthcare workers (HCWs) for varicella immunity and to offer varicella vaccination to those who tested negative for antibody.

HCWs were initially screened via a questionnaire; those with no previous history of chickenpox underwent a blood test for varicella zoster antibody. Varicella vaccine was offered to those who tested negative for antibody and they were monitored for adverse reactions.

Of the HCWs surveyed, 14.7% and 26.9% in phases 1 and 2, respectively, had no previous history of chickenpox. Of these, 55.3% in phase 1 and 26.1% in phase 2 tested negative for antibodies. Thus, the overall seronegativity of all HCWs surveyed was between 6.5% and 7.6%. Among those who tested negative for antibodies, 42.9% in phase 1 and 74% in phase 2 were vaccinated. Hence, the overall vaccination rate in HCWs was 3.2% and 4.8% in phases 1 and 2, respectively. Adverse reactions were observed in 2 (22.2%) HCWs in phase 1 and in 9 (9.3%) in phase 2, consisting mostly of maculopapular rashes or vesicles around the injection site.

Our study shows that 26% to 55% of HCWs with no history of chickenpox and who tested negative for antibody against varicella required vaccination. Hence, in healthcare facilities, varicella screening and vaccination should be offered to all HCWs.