Mass measles immunization campaign: Experience in the Hong Kong Special Administrative Region of China

Abstract

After the 1988 measles outbreak, annual notification rates for measles in Hong Kong SAR between 1989 and 1999 were 0.4-4.9 per 100 000, with peaks in 1992, 1994 and 1997. The first half-year incidence rates per 100 000 were 2.3 in 1997, 0.5 in 1995 and 1.2 in 1996. Monthly notification rates increased from a baseline of < 10 cases to 59 in May 1997. Serological surveillance showed only 85.5% of children aged 1-19 years had measles antibodies. An epidemic, mainly because of failure of the first dose to produce immunity, seemed imminent in mid-1997. A mass immunization campaign targeted children aged 1-19 from July to November 1997. The overall coverage was 77%. The rate of adverse events was low. After the campaign, measles notification fell to 0.9 per 100 000 in 1998. A two-dose strategy and supplementary campaigns will maintain measles susceptibility at levels low enough to make measles elimination our goal.