December 2017 Volume 2
Flu is NOT the Gift to Give: Vaccinate & Get Vaccinated!
Influenza activity is increasing!  Orange County has had an increase in influenza reports in the past week and we are hearing about increases in activity nationally. Vaccination is recommended for all persons 6 months of age and older as it can prevent serious illness, medical visits and hospitalizations. Influenza vaccine is readily available at numerous locations throughout the county; see www.ochealthinfo.com/phs/about/family/flu .
Current Situation:  An increase in influenza activity has been seen in Orange County since week 50 (week ending 12/16), and influenza activity is now widespread in California.    
Over 75% of influenza identified by the Orange County Public Health Laboratory (PHL) has been influenza A H3. Similarly, influenza A has been predominant nationally, comprising 78% of reports overall from participating U.S. clinical laboratories since October 1. Of the B isolates for which lineage has been identified, over 90% have been of the Yamagata lineage (in quadrivalent vaccines only) and less than 10% are B/Victoria (in trivalent and quadrivalent vaccines). No viruses resistant to the neuraminidase inhibitors (i.e., oseltamivir, zanamivir, peramivir) have been identified yet this season. 
Severe influenza illnesses, including, hospitalizations and deaths, have been more common during previous seasons with H3N2 predominance.  
Match to vaccine and vaccine effectiveness.  Antigenic and genetic characterization suggest that the circulating viruses are similar to the reference strains in this season’s vaccine. However, studies suggest that the circulating H3N2 are less similar to the egg-adapted viruses actually used in production of the majority of U.S. influenza vaccines, which could potentially contribute to vaccine effectiveness. The preliminary estimate of vaccine effectiveness against H3N2 was low (10%) in Australia’s just-concluded influenza season, but the significance of these results for the U.S. season is uncertain. Vaccine effectiveness data is not yet available in this country. While effectiveness varies from year to year, the CDC estimates that influenza vaccination averted 40,000 deaths in the U.S. between 2005-2014.  For more information: http://www.nejm.org/doi/full/10.1056/NEJMp1714916 .  
Worldwide seasonal influenza death estimates.  The CDC and global health partners recently reported that between 291,000 and 646,000 people worldwide die from seasonal influenza-related respiratory illnesses each year, which is likely an underestimate since it does not include other conditions exacerbated by influenza which may be instead listed as the cause of death on the death certificate  For more information: https://www.cdc.gov/media/releases/2017/p1213-flu-death-estimate.html .
For clinical guidance , see our last edition of Eye on Influenza or www.cdc.gov/flu/professionals . 

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