H3N2 Flu & You

Jan 12, 2015 | Colleen Nguyen | Outbreak News

Ebola may have made its mark in 2014, but influenza is dominating in early 2015. Having been already declared an epidemic by the Center for Disease Control (CDC), this year’s flu season has led to the death of 26 children and has spread across 46 out of 50 states as of January 9th [1]. While the increase in flu activity and hospitalizations reflect a typical flu season’s cycle, officials have warned that this flu season in particular will be worse than others.
 

The Rise of H3N2

On December 4th, the CDC announced that the dominant strain circulating in this year’s flu season was influenza A type H3N2 [2]. According to Dr. Tom Frieden, Director of the CDC, seasons in which H3N2 strain have dominated have historically been worse than other flu years [2]. To further exacerbate the situation, the vaccine for this season is a match for only 48% of H3N2 strains, meaning that the vaccine will offer limited protection against H3N2 [2]. This discrepancy is accounted for by the flu  virus’ antigenic drift, a process normal for influenza viruses, where slight changes in the genes of influenza viruses occur as a result of viral replication over time [3]. Antigenic drifts happen annually and vaccines are often tailored to respond to the prediction for each season -- but, the change in the H3N2 strain was not noticed until March, missing the deadline to be incorporated into this year’s batch of vaccines [4].
 

Combative Measures: Vaccines, Hygiene, and Antivirals

Despite the mismatch between the prevailing H3N2 and this year’s flu vaccine, it should not deter people from getting vaccinated. Experts agree that vaccines remain the best way to obtain protection from flu, as H3N2 isn’t the only flu strain circulating within the population and the vaccine offers protection against other strains like H1N1, which predominated last year [5]. Additionally, studies have shown that the flu vaccine may curb the course of the disease, as well as lessen any potential complications [6]. Moreover, the CDC states that it’s never too late to get vaccinated, even with the season already underway -- as long as influenza viruses are circulating in the community, a person will be at risk of becoming infected [8].

Further flu prevention measures include washing your hands thoroughly with soap and water and keeping your hands away from your face as much as possible [7]. Should you find yourself struck down with the flu this season, early use of antivirals may offer some reduction in illness severity. Antivirals such as Tamiflu and Relenza may be prescribed for those considered to be in high-risk groups -- often the elderly, young children, and pregnant women [7].
 

When Will It End?

The exact time in which this flu season will end remains unpredictable, but previous seasons have shown that flu activity commonly peaks between December and February [8]. Considering that it’s mid-January -- we’re probably about halfway there. As the season winds down, you can aid in ending the season early by staying home from work or school if you have influenza-like symptoms, practicing good hand hygiene, and implementing any other preventive measures mentioned here.

 

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[1] http://www.usatoday.com/story/news/nation/2015/01/09/flu-deaths-increase/21498903/

[2] http://www.latimes.com/science/sciencenow/la-sci-sn-flu-vaccine-bad-match-h3n2-20141203-story.html

[3] http://www.cdc.gov/flu/about/viruses/change.htm

[4] http://www.washingtonpost.com/news/to-your-health/wp/2014/12/30/this-seasons-flu-activity-has-reached-the-epidemic-threshold-the-cdc-says/

[5] http://www.cdc.gov/flu/pastseasons/1314season.htm

[6] http://www.forbes.com/sites/davidkroll/2014/12/31/get-your-flu-shot-anyway-despite-genetic-drift/

[7] http://www.cnbc.com/id/102306628#

[8] http://www.cdc.gov/flu/about/season/flu-season-2014-2015.htm#flu-activity

 

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