Health Impact Of Influenza Research Articles

Vaccine epidemiology: Its role in promoting sound immunization programs in Japan.

In Japan, the Vaccine Epidemiology Research Group created by the Ministry of Health, Labour and Welfare has played an important role in demonstrating the solid scientific basis for vaccine efficacy and safety since 2002. Members of the group, including epidemiologists, clinicians and microbiologists, have been conducting collaborative studies on vaccines for influenza, pertussis, rotavirus gastroenteritis, polio and pneumonia. So far, the group has achieved several works and contributed to the national vaccination program, including research on the immunogenicity of low doses of influenza vaccine among young children, the immunogenicity and effectiveness of the 2009 influenza pandemic vaccine among various risk groups, the interchangeability of live/inactivated polio vaccines, the health impact of influenza on pregnant women, and the monitoring of influenza vaccine effectiveness using case-control studies with a test-negative design. As part of the 18th Annual Meeting of the Japanese Society of Vaccinology, these accomplishments were featured in the Vaccine Epidemiology Symposium. This report summarizes the recent epidemiological studies on vaccine in Japan as a prologue to the next six papers collected from the symposium.

Réunion, a sentinel territory for influenza surveillance in Europe

In Réunion, a French overseas territory located in the southern hemisphere, increase in influenza activity is generally observed several months earlier than in Europe. Influenza activity is monitored in Réunion through a multi-source surveillance system including sentinel practitioners network, hospital emergency department, laboratory and mortality. Since 2009, three successive influenza epidemics occurred on the island. The largest was observed in 2009 while epidemics in 2010 and 2011 were much weaker. In terms of circulating strains, B viruses were predominant at the beginning of the 2009 epidemic but they were completely evicted once A(H1N1)pdm09 circulation started. In 2010, A(H1N1)pdm09 virus was predominant again, but a constant co-circulation of B viruses was observed. In 2011, A(H3N2) virus circulated. The same viruses were identified a few months later in mainland France in the respective seasons. Since 2009, virus circulation, epidemiological trends and health impact of influenza have been similar to those observed in Europe. Influenza surveillance in Réunion may therefore give reliable early information which should be considered apart from the surveillance in mainland France. Then, it might be even a more suitable predictor for Europe than other temperate southern hemisphere countries.

Prevention and control of influenza A outbreaks in long-term care facilities.

No single virus has the health impact of influenza. Influenza has remained epidemiologically important because it escapes host immune pressure through antigenic variation, is highly contagious, and can cause pneumonia and death in the most susceptible hosts. Viral transmission is most efficient where contact between susceptible hosts is greatest. For humans, this includes institutional settings such as daycare centers, schools, hospitals, and long-term care facilities.Of the three types of influenza, influenza C is relatively nonvirulent. Influenza B is most virulent in children; its antigenic stability presumably allows the adult population to benefit from acquired immunity. Influenza A is virulent in people of all ages, especially in those at the extremes of age or with immunocompromising disease; the attack rate in persons over 70 years of age is four times that of adults under 40 years of age. A major factor accounting for recurrent influenza A epidemics is change in the virus (antigenic drift and shift) that renders the vaccine less efficacious. Influenza epidemics cost billions of dollars and result in thousands of deaths annually. This discussion will focus on the prevention and treatment of influenza A in the long-term care facility.