As we've mentioned before (see A Diverse Flu Season) the world rarely marches in lockstep when it comes to seasonal flu epidemics. Years when we've seen H3N2 dominate in North America, we often see H1N1 driving Russia's, or Eastern Europe's flu season.
This year is much the same, with an early and unusually robust appearance of Influenza B thrown into the mix.Somewhat surprisingly, even across Europe, there is a fair amount of diversity in flu types leading the charge. While the UK (much like North America) is being hard hit by H3N2, across the Channel in France, H1N1 is causing most of the misery.
And Influenza B - which usually arrives in the spring, after Influenza A runs its course - is being widely reported as well.From China, Sharon Sanders and the newshounds at FluTrackers are seeing a number of media reports describing a predominately Influenza B driven flu epidemic. These recent reports are translated and posted in their China Seasonal Flu Tracking thread.
China - Sichuan Province - Chengdu: outpatient emergency clinics saturated with flu patients
China - Beijing pediatric outpatient flu visits up 81.44% over the same week in the previous year - December 29, 2017
China - At least 61 flu outbreaks reported in schools since December 2017 in Anhui Province
China - Beijing influenza virus activity is still high, CDC letter to parents to strengthen protection
China - Shandong Province - Weifang: many families with flu, anti-influenza virus drugs out of stock
Today China's National Health and Family Planning Commission (NHFPC) held a news conference on this winter's unusually severe flu epidemic.
They suggest (among other factors) that the unexpected early arrival and dominance of Influenza B (Yamagata) - a lineage that has been uncommon in China the past few years - has caught the community without much immunity.First some translated excerpts, the I'll have a postscript:.
Influenza is an acute respiratory tract caused by the influenza virus infection, easy to pop in the crowd in the spring and winter. Flu begins abruptly, mostly self-limiting, but some due to complications such as pneumonia may appear to develop severe flu.
Since winter 2017, the level of influenza activity increased rapidly, and is still on the rise. And more hospital emergency department and hospitalized patients, critically ill patients increased pressure treatment.
Expert analysis that this winter influenza high is caused by the combination of factors, mainly include: Winter is the influenza high season, this winter climate anomaly, this year the dominant strains (b-type Yamagata) has not become the dominant strains for many years, resulting in a lack of immune barriers to the population, susceptible to increased population. The peak of influenza activity is expected to continue for some time, and the level of influenza activity will gradually decline as schools and young institutions come into winter.
The State Council attaches great importance to prevention and treatment of flu this winter. National Health and Family Planning Commission of the State Council in accordance with the requirements, do a good job to deal with the flu, issued "Notice on the 2018 flu prevention and control work," focus on the following work, and ensure people's health and safety:
(Continue . . . )
The good news - at least for those who were vaccinated this year with the quadrivalent flu vaccine (contains H3N2, H1N1, and 2 B strains) - is that three of the four vaccine strains are expected to provide relatively decent protection.
Those who received the trivalent vaccine are probably not going to see a lot of protection against H3N2 or Influenza B (Yamagata).It remains to be seen whether China will see a `second wave' of Influenza A later in the spring. But China's heavy flu activity may be dampening down human infections with H7N9 and H5N6, since there is some evidence to suggest getting one type of flu can provide some temporary immunity from other strains.
It's called the Temporary Immunity Hypothesis, and while not entirely proven, it would explain why the last 6 pandemics have all emerged in the Northern Hemisphere in late spring or early summer (see PLoS Comp. Bio.: Spring & Early Summer Most Likely Time For A Pandemic) after the end of the regular flu season.Whatever the cause, and for as long as it lasts, we'll take it.