Eurosurveillance - Volume 14, Issue 35, 03 September 2009

This report describes the assessment of the secondary attack rate (SAR) and the effectiveness of post-exposure antiviral prophylaxis among household contacts in the first domestic outbreak of a novel influenza A(H1N1)v between mid-May and early June 2009 in Kobe city, Japan. Of the 293 subjects, 14 (4.8%) household contacts met the case definition and most secondary cases were probably infected around the time of symptom onset date of the respective index case. The SAR among household contacts who did not receive prophylaxis was 7.6%, similar to the rate of seasonal influenza, and the attack rate in siblings was significantly higher than that in parents. We conclude that it is important to establish routine infection control measures for households in order to prevent the spread of the virus among household contacts and, possibly, to the community. We could not conclude whether antiviral prophylaxis was effective or not. However, among close contacts with underlying disease who received prophylaxis, nobody developed a severe form of the disease.

The outbreak of pandemic influenza (H1N1) began in Bolivia on 25 May 2009. Between May and August, the National Center of Tropical Disease (CENETROP) analysed by RT-PCR 7,060 samples of which 12.7% were positive. A preliminary analysis of the 895 confirmed cases identified between May and August 2009 describes epidemiological and clinical characteristics. After the first imported cases from the United States and Peru, the locally acquired infections predominated (90%). The number of cases was highest in the age group of 10 to 29 year-olds, and 89.6% of cases were observed in people under the age of 40 years. Fever, cough, nasal discharge and headache remained the main symptoms.

On 28 August 2009, French authorities reported five cases of chikungunya fever on Réunion Island: three confirmed, one probable, and one suspected case under investigation. All three confirmed patients presented with an acute febrile syndrome, arthralgia, myalgia and cutaneaous rash. All live in the same area on the western side of the island.

Supported by an economic evaluation, rotavirus vaccine is introduced into the national immunisation schedule in Finland. The vaccination programme has been estimated to be reasonably cost-effective. Given at the age of two, three and five months, the vaccine is expected to prevent annually in Finland among children under the age of five years approximately 2,000 rotavirus diarrhoea episodes needing hospitalisation, and over 10,000 outpatient visits. The impact of the programme will be evaluated in 2011 by repeating the economic analysis and carefully monitoring adverse events.

Following the licensure of the Oka/Merck varicella vaccine in Italy in January 2003, the Sicilian health authorities launched a universal vaccination programme in all nine Local Health Units. A two-cohort vaccination strategy was adopted to minimise the shift of the mean age of varicella occurrence to older age groups, with the goal of vaccinating with one dose at least 80% of children in their second year of life and 50% of susceptible adolescents in their 12th year of life. Two studies were implemented in parallel to closely monitor vaccination coverage as well as varicella incidence. Overall, the programme achieved its target, with 87.5% vaccine coverage for the birth cohort 2005 and 90.2% for adolescents born in 1995 and 1996. Varicella surveillance data obtained from a total of 28,188 children (0-14 years-old) monitored by family paediatricians showed a decline in incidence rates from 95.7 (95% confidence interval (CI): 72.2-126.8) for 1,000 person-years (PY) in 2004 to 9.0 (95% CI: 6.4-12.6) for 1,000 PY in 2007. In Europe, the only similar experience is the routine childhood varicella vaccination programme in Germany that started in 2004 with a single dose at the age of 11-14 months. The two-cohort universal vaccination programme implemented in Sicily, as well as the network for the surveillance study, can offer a model to other European countries that are considering introducing universal childhood varicella vaccination.