[An influenza pandemic in Russia as a part of a global spread of the influenza A(H1N1)pdm09 in 2009-2011].

The comparison of the first and second waves of the pandemic influenza A(H1N1)pdm09 in the world and Russia was performed on the basis of weekly reports of Regional offices for Europe and on the data of the Federal Center for Influenza on a weekly incidence of influenza and acute respiratory viral infections, hospitalization, and mortality from the influenza in the age groups of population in 49 cities of the Russian Federation. The first wave of the pandemic, which continued in the countries of the world all summer, was of mixed etiology and, in spite of the availability of imported cases, has not caused a steep increase in Russia. The second wave of the pandemic in the countries of the Southern hemisphere was less intense. In the countries of the Northern hemisphere (in autumn 2009), on the contrary, it was more intensive, which was associated with different seasonality of influenza in these hemispheres. In Russia, the second wave (2011) was of a lesser intensity as compared to the first with respect to the duration in the country and in urban areas, the incidence in the entire population, including schoolchildren and adults, the rate of hospitalization and case fatality rate reduction of laboratory-confirmed influenza infection. The duration of the last pandemic of 2009 was the same as in 1957 and 1968, and longer than in 1977. The morbidity was one-half less than in the pandemic of 1957 and 1968, and was approaching the pandemic 1977. At the same time, the incidence in children 3-6 and 7-14 years was higher than in previous pandemics.

[Epidemiology of influenza A/California/07/09 (H1N1) in foreign countries in 2009 - 2010 season].

AIM: Study of spread ofa new influenza variant A(H1N1) in the world in 2009. MATERIALS AND METHODS: Analysis of WHO weekly situation reports on influenza epidemic in the countries of the Northern and Southern hemisphere. RESULTS: The first laboratory confirmed cases ofA/California/07/09 (H1N1) were registered in the countries of the Northern hemisphere in 10 days, and in other continents--in 1 month after the increase of morbidity. In the countries of Northern hemisphere 2 increases of A/California/07/09 (H1N1) morbidity were present--spring and autumn, and in the autumn period an increase of population morbidity, rate of hospitalization and number of lethal outcomes was noted. Only in Canada autumn increase of morbidity was not accompanied by an increase in severe influenza cases. In the Southern hemisphere a single but longer increase of morbidity was registered during the summer period. In the South-eastern Asia 2 increases were mostly present with a higher level during the first one. CONCLUSION: A significant increase in morbidity in the autumn periodand its decrease at the same time in the Southern hemisphere are determined by varying seasonality of influenza in the countries of Northern and Southern hemisphere. Spring increase of morbidity was of mixed etiology; and in the autumn period influenza A/ California/07/09 (H1N1) virus dominated in the etiology of diseases.