Original Article: A primary school outbreak of pandemic 2009 influenza A (H1N1) in China

Abstract

Please cite this paper as: Huai et al. (2010) A primary school outbreak of pandemic 2009 influenza A (H1N1) in China. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00150.x. Background We investigated the first known outbreak of pandemic 2009 influenza A (H1N1) at a primary school in China. Objectives To describe epidemiologic findings, identify risk factors associated with 2009 H1N1 illness, and inform national policy including school outbreak control and surveillance strategies. Methods We conducted retrospective case finding by reviewing the school’s absentee log and retrieving medical records. Enhanced surveillance was implemented by requiring physicians to report any influenza‐like illness (ILI) cases to public health authorities. A case–control study was conducted to detect potential risk factors for 2009 H1N1 illness. A questionnaire was administered to 50 confirmed cases and 197 age‐, gender‐, and location‐matched controls randomly selected from student and population registries. Results The attack rate was 4% (50/1314), and children from all grades were affected. When compared with controls, confirmed cases were more likely to have been exposed to persons with respiratory illness either in the home or classroom within 7 days of symptom onset (OR, 4·5, 95% CI: 1·9–10·7). No cases reported travel or contact with persons who had traveled outside of the country. Conclusions Findings in this outbreak investigation, including risk of illness associated with contacting persons with respiratory illness, are consistent with those reported by others for seasonal influenza and 2009 H1N1 outbreaks in school. The outbreak confirmed that community‐level transmission of 2009 H1N1 virus was occurring in China and helped lead to changes in the national pandemic policy from containment to mitigation.

H1N1 outbreak in a medical college of Pakistan: Implications of control in a resource poor setting

“…The overall attack rate for influenza-like illness that describes our case definition of presumed H1N1 in this study (14%) is comparable to an outbreak reported at a large university at Delaware (10%), 6 although this is much higher than that seen in outbreaks at a school in China (4%) 5 and a school in england (2%). 4 One possible reason for the difference could be the fact that students at Delaware and Aga Khan University live on campus and hence the close contact increases the transmissibility of the virus.…”

“…An interesting observation was that the outbreak occurred in November as opposed to April to June as noted in other reports. [4][5][6][9][10][11] An outbreak was noted in Saudi Arabia in the month of October as well.…”

“…3 H1N1 has been reported at a number of universities and school across the globe. [4][5][6][7][8] these outbreaks present with different features and patterns and have been dealt with in a variety of ways. regardless the lack of guidelines for H1N1 outbreaks in universities and schools prove to be a challenge in tackling such conditions.…”

School closures and influenza: systematic review of epidemiological studies

“…10 One limitation of the datasets is that ascertainment may have changed during the outbreaks, due to changes in surveillance and care-seeking behaviour. Increases in ascertainment during an outbreak could obscure any reductions in incidence during school closures (eg in one study, enhanced surveillance began the day the school closed 55 ). Conversely, the proportion of patients who undergo virological testing may be reduced late in an outbreak, and in some settings (eg New Zealand 14 ) patients with ILI were discouraged from consulting GPs during the 2009 pandemic.…”

Epidemiological and Virological Characteristics of Pandemic Influenza A (H1N1) School Outbreaks in China in 2009

“…Some studies have been conducted in schools and the results indicated that the attack rates of the H1N1 pandemic range from 4% to 42.4% [14], [15].…”