Influenza season 2012-2013 in Europe: moderate intensity, mixed (sub)types.

This paper summarizes influenza activity in the European Union/European Economic Area (EU/EEA) in 2012-2013. The influenza season 2012-2013 in Europe lasted from early December to late April. Overall the severity of the season could be described as moderate, based on the ILI/ARI consultation rates and the percentage of sentinel specimens positive for influenza compared to previous seasons. Both influenza A and B viruses circulating accounted for 47% and 53% of positive sentinel specimens, respectively, with both A(H1) and A(H3) varying for dominance. Compared to outpatients, the proportion of laboratory-confirmed influenza hospitalized cases infected by A(H1N1)pdm09 was significantly higher in middle-aged patients (33% vs. 17%, χ 2 = 66·6, P < 0·01). Despite a relatively good match between vaccine and circulating strains, vaccine effectiveness was estimated to be moderate.

Influenza-related deaths--available methods for estimating numbers and detecting patterns for seasonal and pandemic influenza in Europe.

Two methodologies are used for describing and estimating influenza-related mortality: Individual-based methods, which use death certification and laboratory diagnosis and predominately determine patterns and risk factors for mortality, and population-based methods, which use statistical and modelling techniques to estimate numbers of premature deaths. The total numbers of deaths generated from the two methods cannot be compared. The former are prone to underestimation, especially when identifying influenza-related deaths in older people. The latter are cruder and have to allow for confounding factors, notably other seasonal infections and climate effects. There is no routine system estimating overall European influenza-related premature mortality, apart from a pilot system EuroMOMO. It is not possible at present to estimate the overall influenza mortality due to the 2009 influenza pandemic in Europe, and the totals based on individual deaths are a minimum estimate. However, the pattern of mortality differed considerably between the 2009 pandemic in Europe and the interpandemic period 1970 to 2008, with pandemic deaths in 2009 occurring in younger and healthier persons. Common methods should be agreed to estimate influenza-related mortality at national level in Europe, and individual surveillance should be instituted for influenza-related deaths in key groups such as pregnant women and children.

Overrepresentation of influenza A(H1N1)pdm09 virus among severe influenza cases in the 2011/12 season in four European countries.

In France, Ireland, Spain and the United Kingdom, the influenza season 2011/12 started in the final weeks of 2011 and has been dominated by influenza A(H3) viruses with minimal circulation of influenza A(H1N1) pdm09 and B viruses. A relatively greater proportion, however, of influenza A(H1N1)pdm09 viruses were reported in hospitalised laboratory-confirmed influenza cases in four countries. Compared to the season 2010/11, the proportion of subtype A(H3) among hospitalised cases has increased, associated with a larger proportion of cases in the youngest and oldest age groups.

[Influenza A/H1N1 pandemic: central European experience and perspective of prevention and control of this disease]. / Influenza A/H1N1 pandémique: expérience et perspective du Centre européen de prévention et de contrôle des maladies.

When the influenza pandemic A/H1N1 emerged in 2009, European countries activated their national pandemic plan that were initiated in 2005 when ECDC was established in Stockholm. This agency from the European Commission played its role to strengthen capacities of Member States. ECDC essentially focused attention on surveillance and its reinforcement, epidemic intelligence and guidance. Nevertheless, main challenges remain to be met: continuous adjustment of assumptions, weaknesses in national plans (e.g. no stockpile of antibiotics), paucity of investment in scientific research, no control of transmission from human to animal, persistence of the impact of the pandemic in the subsequent years and eventually the worrying unpreparedness of developing countries that paid a huge toll during previous pandemics.

Pandemic planning.

During the previous century, three influenza A pandemics occurred with a variable severity. The two latter were explained by a genetic re-assortment and false alarms without pandemic spread were observed later by the same mechanism or by direct animal infection. The likelihood that such an event occurs again is high and each country has to be prepared for facing what could be a catastrophe. The last event in Hong Kong in 1997 where six persons died, has allowed refining the definitions and phasing a pandemic threat from the moment that a novel virus is discovered. WHO implemented 50 years ago a large network of surveillance with five collaborating centres, including the animal influenza centre of Memphis, and 110 national influenza centres. These centres are encouraged to prepare or improve a national contingency plan that could reduce importantly medical and socio-economic consequences of an influenza A pandemic. Countries or regions are recommended to use these guidelines that provide a framework for preparing an appropriate and proportionate response.

[Influenza: prevention and treatment]. / Grippe: prévention et traitement.

Prevention of influenza for persons at risk with inactivated vaccine remains the best way for attenuating the impact of influenza epidemics if persons to be vaccinated are correctly identified. In current recommendations, the lower cut off age is controversial, but new arguments on mortality associated with influenza suggest to lower the age to 45 for vaccination. Moreover immunization of health care workers is essential by decreasing transmission to susceptible patients and by reducing absenteeism of essential people during epidemics. Intranasal attenuated live vaccine seems to be of particular importance essentially in children and could replace the current vaccine in a near future. The role of chemoprophylaxis by inhibitors of neuraminidase needs further studies, but preliminary controlled trials have demonstrated a certain efficacy by controlling outbreaks in health care institutions. Treatment of influenza by these latter antivirals already has defined indications and a larger use currently lies on convincing arguments. By reducing inappropriate use of antibiotics, an extended use of neuraminidase inhibitors is of particular interest even if it is not a valuable argument, stricto sensu, for good medical practices.

Control of influenza. Public health policies.

The control and management of influenza are currently based on the surveillance, prevention and treatment of the disease. Almost all European countries have influenza immunization policies for populations considered as being at-risk, but there are large disagreements about the meaning of "risk", and the levels of vaccine use vary greatly country by country. In the near future, new vaccines and specific anti-viral drugs will need to adapt and to extend current recommendations, but meanwhile increasing vaccination coverage, improving and up-dating national policies and their achievement are the only ways to reduce the recurrent burden of influenza epidemics for both individuals and society.

The next influenza pandemic: lessons from Hong Kong, 1997.

The 1997 Hong Kong outbreak of an avian influenzalike virus, with 18 proven human cases, many severe or fatal, highlighted the challenges of novel influenza viruses. Lessons from this episode can improve international and national planning for influenza pandemics in seven areas: expanded international commitment to first responses to pandemic threats; surveillance for influenza in key densely populated areas with large live-animal markets; new, economical diagnostic tests not based on eggs; contingency procedures for diagnostic work with highly pathogenic viruses where biocontainment laboratories do not exist; ability of health facilities in developing nations to communicate electronically, nationally and internationally; licenses for new vaccine production methods; and improved equity in supply of pharmaceutical products, as well as availability of basic health services, during a global influenza crisis. The Hong Kong epidemic also underscores the need for national committees and country-specific pandemic plans.

European Influenza Surveillance Scheme on the Internet.

In 1995, The European Influenza Surveillance Scheme was created with the participation of eight networks from seven countries. The main objectives were to continue the previous CARE Telematics Network and to adapt the project to the Internet environment as well as to improve substantially the quality of the surveillance according to new epidemiological requirements. Clinical and virological data from the general population and hospitals are collected in an interactive real-time database which can then be used for data entry, queries and consultations. Research programmes have been undertaken in various fields such as standardisation of clinical data and comparability between countries. Validation and security processes guarantee the quality assurance as well as regular assessment by the steering committee. Two additional countries will participate during the next influenza season (1997-98). This will represent an early warning system in a region of approximately 264 million inhabitants.

Influenza vaccination in 22 developed countries: an update to 1995.

This study expands and updates through 1995 our earlier report on influenza vaccine use in 18 developed countries. Five of the six countries with high levels of vaccine use in 1992 (> or = 130 doses/1000 population) showed little change or slight declines over the subsequent 3 years. The exception was the United States, where a new federal program for vaccination reimbursement for the elderly helped to increase vaccine distribution from 144 to 239 doses/1000 population. The six countries with medium levels of vaccine use in 1992 (76-96 doses/1000 population) increased to > or = 100 doses/1000 population by 1995. Among the six low-use countries in 1992 (< or = 65 doses/1000 population), only Finland showed substantial improvement (96 doses/1000 population) in 1995. Four new countries were added to the study. In Germany, vaccine use increased to 80 doses/1000 population in 1995, but in Ireland it remained at a low level (48 doses/1000 population). In Korea, vaccine use increased from 17 to 95 doses/ 1000 population during the period 1987-1995. In Japan, very high levels of vaccine use (approximately 280 doses/1000 population) in the early 1980s were associated with vaccination programs for school children. However, vaccine use fell precipitously when these programs were discontinued, and only 2 and 8 doses/1000 population were used in 1994 and 1995, respectively. In all 22 countries, higher levels of vaccine use were associated with vaccination reimbursement programs under national or social health insurance and were not correlated with different levels of economic development. Excluding Japan, in 1995 there was still a greater than fourfold difference between the highest and lowest levels of vaccine use among the other 21 countries in the study. Given its well established clinical effectiveness and cost-effectiveness, none of these countries has yet achieved the full benefits of its programs for influenza vaccination.