Sunday, January 21, 2018

Russia As An Outlier in This Year's Flu Epidemic

Epi Week 2 - 2018


While the United States, Western Europe, and Asia are all dealing with a moderately severe-to-severe flu season, one usually hard-hit region of the world has so far gotten a pass this winter; Russia.

Russia - which often reports severe winter flu seasons even when the rest of the world has only mild or moderate flu - has yet to reach their epidemic threshold this winter - coming closest (under by 1.4%) in early December (week 51).

As we saw two weeks ago in Eurosurveillance: Changes In Timing Of Influenza Epidemics - WHO European Region 1996-2016, over the past 2 decades Russia's flu seasons have tended to peak earlier with each passing year.  
There is still time, however, for another late season flu surge in Russia.
While flu activity is up slightly this week over last, the latest surveillance report from the Russian Research Institute of Influenza, shows a remarkably mild flu season for January.  

Week 08.01.2018-14.01.2018

Influenza and ARI morbidity data

Epidemiological data show increase of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the new national baseline (calculated in country) for 2017-2018 season (72.6) by 29.2%.

ILI and ARI epidemic thresholds were exceeded in 12 of 61 cities collaborating with two WHO NICs in Russia.
Cumulative number of diagnosed influenza cases
Cumulative results of influenza laboratory diagnosis by different tests were submitted by 51 RBLs and two WHO NICs. According to these data as a result of 1668 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza type A virus and 0.9% for influenza type B virus. 



Influenza and ARI morbidity data.  Increased influenza and other ARI activity was registered during the week 02.2018 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the national baseline by 29.2%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza  was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza A virus and 0.9% for influenza type B virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 22.9% of investigated patients by IFA and 19.2% by PCR. 

Antigenic characterization. 7 influenza viruses were characterized antigenically including 5 influenza A(H3N2) strains and 2 influenza type B strains. All influenza A(H3N2) strains were related to influenza A/Hong Kong/4801/2014 virus. All influenza type B strains were belonged to Yamagata line and were like B/Phuket/3073/2013 reference virus.

Genetic characterizationOne influenza A(H3N2) virus was characterized in Saint-Petersburg NIC. Virus belonged to genetic subgroup 3C.2a1 and was like A/Bolzano/07/2016 reference virus. 4 influenza A(H3N2) strains from clinical samples were characterized in Saint-Petersburg NIC. Viruses belonged to genetic subgroup 3C.2a and were like A/Hong Kong/4801/2014 reference virus.

In sentinel surveillance system clinical samples from 87 SARI and ILI/ARI patients were investigated by rRT-PCR. 5 influenza cases were detected among SARI patients, including 1 influenza A(H1N1)pdm09 case, 3 influenza A(H3N2) cases and 1 influenza B case. Among ILI/ARI patients 5 influenza cases were detected, including 1 influenza A(H1N1)pdm09 case, 1 influenza A(H3N2) case and 3 influenza B cases.

This week's weekly (translated) summary from  Rospotrebnadzor reflects the low incidence of flu, along with high (46.6%) vaccination rate - a product of a massive campaign that began two years ago - for the current flu season.

On the situation on the incidence of influenza and acute respiratory viral infection and the course of immunization of the population in the Russian Federation


According to the WHO EURO in the European region recorded growth of influenza caused by influenza virus subtypes A (H3N2) and type B. +
At week 02 (08.01.2018-14.01.2018) in the Russian Federation there is a low incidence of influenza and SARS.
By the total population exceeding the weekly epidemic threshold incidence of SARS and influenza reported in 3 of the Russian Federation. Excess epidporoga the central city without exceeding epidporoga on the subject of the Russian Federation, recorded in 2 cities of Russian Federation.
Among children in age group of 0-2 years week thresholds of disease epidemic of SARS and influenza are exceeded in 5 Russian regions, among children in the age group 3-6 years - in 8 regions of Russia, among children in the age group 7-14 - in 6 regions of Russia, among people older than 15 years - in 3 of the Russian Federation.
Laboratory examined the reporting week, more than 3.3 thousand people in the 57 -. E cases of influenza A viruses are found in 32 - x - influenza B viruses
In the structure of positive findings parainfluenza viruses accounted for 16%, adenoviruses - 17%, RS viruses - 30%, other viruses are not influenza etiology - 35%. The proportion of influenza viruses in the structure of the positive findings was 10%.
Rospotrebnadzor continues to monitor the progress of immunization against influenza.
On 12/01/2018 at the expense of the federal budget vaccinated more than 17 million. Children (99.9% of the planned number) and more than 40.6 million. Adults (99.9%), in Vol. H. The more than 174 thousand. Pregnant women
From other sources vaccinated 8.1 million people, including through employer -. 6.6 million people..

Summary vaccinated more than 67.3 million. People (46.6% of the population).
The situation is under the control of Rospotrebnadzor.

All of which proves, once again, how fickle and unpredictable seasonal flu can be.

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