Tuesday, November 01, 2016

WHO Global Influenza Update #275


This time of year, when influenza activity is in steep decline in the Southern Hemisphere but not yet surging north of the equator, we look around the globe for clues as to what our upcoming flu season might have in store for us.

Last year, North America saw one of the mildest flu seasons in recent years - barely cracking the P&I Epidemic threshold (see CDC chart below) while Eastern Europe and Russia were hit very hard (see ECDC Risk Assessment : Reports Of Severe A(H1N1)pdm09 In Europe).

This year, however, early indications are that H3N2 is likely to be the dominant flu strain, and years when H3N2 dominates tend to be more severe, particularly for the elderly.

Yesterday the World Health Organization published their bi-weekly global influenza report - current through Oct 16th - that shows influenza as either declining or at low levels around the world.

What Influenza A there is to be found, however, is almost all (well, 93.4%) H3N2.

Influenza update - 275

31 October 2016, - Update number 275, based on data up to 16 October, 2016


Influenza activity in temperate southern hemisphere countries continued to decrease or remained low. Influenza activity in the temperate zone of the northern hemisphere remained at inter-seasonal levels.
  • In temperate South America, influenza and respiratory syncytial virus (RSV) activity decreased throughout the sub-region.
  • In the temperate countries of Southern Africa, influenza detections continued to decrease.
  • In Oceania, influenza virus activity continued to decrease in the last few weeks. Influenza A(H3N2) remained the dominant circulating influenza virus. In Australia, activity decreased from the peak in September.
  • In the Caribbean countries, influenza and other respiratory virus activity remained low except in Cuba where influenza B virus detections continued and in French Guiana where ILI activity and influenza detections of influenza A(H3N2) viruses increased slightly. In Central America, influenza virus activity in most countries remained low, except in Costa Rica where there was a slight increase in influenza detections. RSV continued to circulate in several countries as the predominant respiratory virus.
  • In tropical South America, respiratory virus activities remained low.
  • In tropical countries of South Asia, influenza activity was low.
  • In South East Asia, a decreasing trend in influenza detection was observed, although detections continued to increase in Lao People's Democratic Republic (PDR) and Thailand
  • In tropical Africa, Burkina Faso and La RĂ©union Island (France) reported slightly increased influenza A(H3N2) virus activity.
  • In Northern temperate Asia, influenza activity remained low with predominantly influenza A(H3N2) detections in northern China.
  • In North America and Europe, influenza activity was low with few influenza virus detections and ILI levels below seasonal thresholds. In the United States, RSV activity increased.
  • National Influenza Centres (NICs) and other national influenza laboratories from 82 countries, areas or territories reported data to FluNet for the time period from 03 October 2016 to 16 October 2016 (data as of 2016-10-28 04:04:36 UTC).The WHO GISRS laboratories tested more than 70925 specimens during that time period. 2979 were positive for influenza viruses, of which 2540 (85.3%) were typed as influenza A and 439 (14.7%) as influenza B. Of the sub-typed influenza A viruses, 135 (6.6%) were influenza A(H1N1)pdm09 and 1911 (93.4%) were influenza A(H3N2). Of the characterized B viruses, 21 (25.9%) belonged to the B-Yamagata lineage and 60 (74.1%) to the B-Victoria lineage.

Although the effectiveness of the seasonal flu vaccine can vary from year to year, last year the CDC estimated it was nearly 50% effective in preventing the flu (see Seasonal Influenza Vaccine Effectiveness, 2005-2016).

While no guarantee, a 50% reduction in the odds of getting the flu is still nothing to sneeze at.  And there is evidence to suggest that even if your shot doesn't prevent the flu, it make make your illness less severe.
As an added bonus, in recent years we've seen studies suggesting the flu jab may also provide significant protection against coronary events (see UNSW: Flu Vaccine Provides Significant Protection Against Heart Attacks).

I get my shot every year, and urge others to consider doing so as well (see #NatlPrep: Giving Preparedness A Shot In The Arm).

While the vaccine can’t promise 100% protection, it – along with practicing good flu hygiene (washing hands, covering coughs, & staying home if sick) – remains your best strategy for avoiding the flu and staying healthy this winter.  

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