Interventions and Respiratory Specimen Screening of Close Contacts to Control an Outbreak of Pandemic Influenza A (H1N1) Virus in a Tour Group, China, 2009

Abstract

From 2-8 Jun 2009, a 2009 H1N1 outbreak occurred in a tour group of 30 people from five Chinese provinces and two foreign countries. We described the interventions taken in response to this tour group outbreak and reported the results of those efforts. Potential close contacts were identified and classified into five categories. Demographic and contact information were obtained to trace them back. Once contacted, close contacts were given seven-day medical observation, and sequential throat swabs were collected from all close contacts and tested using RT-PCR to determine infection and clarify diagnosis. 172 close contacts were identified. Among them, 163 (95%) were successfully traced back for medical observation at home [20 (12%)], in designated hotels [103 (63%)] and in hospital [40 (25%)] by 17 Jun 2009. Ten of 11 (91%) contacts under medical observation developed symptoms and were confirmed as secondary cases by RT-PCR testing; the other one tested negative. Tour groups that bring strangers together from many distant locations for a few days can result in accelerated transmission of influenza and likely other respiratory diseases. Public health policies for the control and prevention of respiratory diseases need to address potential transmission by such groups.