Effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand, in 2013.

This study reports the first vaccine effectiveness (VE) estimates for the prevention of general practice visits and hospitalisations for laboratory-confirmed influenza from an urban population in Auckland, New Zealand, in the same influenza season (2013). A case test-negative design was used to estimate propensity-adjusted VE in both hospital and community settings. Patients with a severe acute respiratory infection (SARI) or influenza-like illness (ILI) were defined as requiring hospitalisation (SARI) or attending a general practice (ILI) with a history of fever or measured temperature ≥38 °C, cough and onset within the past 10 days. Those who tested positive for influenza virus were cases while those who tested negative were controls. Results were analysed to 7 days post symptom onset and adjusted for the propensity to be vaccinated and the timing during the influenza season. Influenza vaccination provided 52% (95% CI: 32 to 66) protection against laboratory-confirmed influenza hospitalisation and 56% (95% CI: 34 to 70) against presenting to general practice with influenza. VE estimates were similar for all types and subtypes. This study found moderate effectiveness of influenza vaccine against medically attended and hospitalised influenza in New Zealand, a temperate, southern hemisphere country during the 2013 winter season.

Epidemiological and genetic characteristics of norovirus outbreaks in long-term care facilities, 2003-2006.

To identify the epidemiological and genetic characteristics of norovirus (NoV) outbreaks and estimate the impact of NoV infections in an older population, we analysed epidemiological and laboratory data collected using standardized methods from long-term care facilities (LTCFs) during 2003-2006. Faecal specimens were tested for NoV by real-time reverse transcriptase-polymerase chain reaction. NoV strains were genotyped by sequencing. Of the 234 acute gastroenteritis (AGE) outbreaks reported, 163 (70%) were caused by NoV. The annual attack rate of outbreak-associated NoV infection in LTCF residents was 4%, with a case-hospitalization rate of 3·1% and a case-fatality rate of 0·5%. GII.4 strains accounted for 84% of NoV outbreaks. Median duration of illness was longer for GII.4 infections than non-GII.4 infections (33 vs. 24 h, P<0·001). Emerging GII.4 strains (Hunter/2004, Minerva/2006b, Terneuzen/2006a) gradually replaced the previously dominant strain (Farmington Hills/2002) during 2004-2006. NoV GII.4 strains are now associated with the majority of AGE outbreaks in LTCFs and prolonged illness in Oregon.

Rotavirus epidemiology: the Asian Rotavirus Surveillance Network.

Availability of new rotavirus vaccines has highlighted the need to collect local disease and economic burden data to aid decision makers at global, regional and country level. The World Health Organization and the GAVI Alliance recommended that generic protocols be used and that regional surveillance networks be established to collect these data, thereby helping to fast-track the introduction of these new vaccines into developing countries. Nine countries and regions participated in the first phase of the Asian Rotavirus Surveillance Network (ARSN), which collected data over a 2-year period during 2001-2003. Overall 45% of diarrhoea admissions in the region were positive for rotavirus, which was higher than had been anticipated. Significant rotavirus strain diversity was noted during the surveillance period. Data collection for a second phase of the ARSN commenced in 2004 and included a greater proportion of poorer countries that would in future be eligible for funding support for rotavirus immunization from GAVI. Limited economic evaluations in Asia have demonstrated the potential for new rotavirus vaccines to be cost-effective but more local analyses are required. Despite the ARSN's comprehensive data from a mix of developed and developing countries, Asia has lagged the Americas in terms of the introduction of rotavirus vaccines into National Immunization Programmes (NIPs). Lack on rotavirus vaccine efficacy data in Asia, particularly in poorer populations, will have contributed to this delay. Thus ensuring that all global regions are simultaneously involved in the evaluation of new vaccines from the beginning and also encouraging more regional collaborations of Ministry of Health representatives could help to accelerate the introduction of new vaccines into NIPs.

Options for improvement of the Dutch measles vaccination schedule.

We investigated which vaccination schedule gives best protection to the vaccinating population, in case of a measles epidemic in pockets of unvaccinated individuals. We explored the effect of an additional measles vaccination (at 6 or 9 months), advancing the first measles-mumps-rubella (MMR) vaccination from 14 to 11 months, and advancing the second MMR from 9 to 4 years. Measures of protection among vaccinees (percentage of susceptibles, number of reported cases, percentage of lifetime spent susceptible) were estimated with a mathematical model of the impact of antibody level on seroconversion and immunity. Advancing the age of second MMR vaccination prevents considerably more cases among vaccinees than an extra early measles vaccination or advancing the age of first MMR vaccination.