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.