title: A cluster of patients infected with I221V influenza b virus variants with reduced oseltamivir susceptibility--North Carolina and South Carolina, 2010-2011.
abstract: BACKGROUND
  During 2010-2011, influenza B viruses with a novel neuraminidase substitution, denoted I221V (B/I221V), associated with reduced in vitro oseltamivir susceptibility were detected in North Carolina.
  
  
  METHODS
  We determined the prevalence of I221V among B viruses submitted to the Centers for Disease Control and Prevention for antiviral resistance surveillance, including all B viruses submitted to North Carolina and South Carolina state laboratories, during October 2010-September 2011.We conducted chart reviews and telephone interviews to characterize North Carolina and South Carolina patients with B/I221V vs wild-type B virus infection (B/WT).
  
  
  RESULTS
  We detected I221V in 45 (22%) of 209 B viruses from North Carolina and 8 (10%) of 82 B viruses from South Carolina. We detected I221V in 3 (0.3%) of 881 B viruses tested from 45 other states. B/I221V infection was not associated with differences in underlying conditions or illness severity, compared with B/WT infection. No patients with B/I221V infection received oseltamivir prior to specimen collection. Among patients who completed oseltamivir, those with B/I221V infection reported a longer duration until illness resolution (5 vs 3 days; P = .02).
  
  
  CONCLUSIONS
  B/I221V cocirculated with B/WT in North Carolina and South Carolina during 2010-2011. I221V did not alter illness severity but may have reduced oseltamivir effectiveness. Thus, global surveillance for I221V is important.
authors.affiliation: Epidemic Intelligence Service and Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. sGarg1@cdc.gov
authors.forename: Shikha
authors.initials: S
authors.lastname: Garg
authors.forename: Zack
authors.initials: Z
authors.lastname: Moore
authors.forename: Nicole
authors.initials: N
authors.lastname: Lee
authors.forename: John
authors.initials: J
authors.lastname: McKenna
authors.forename: Amber
authors.initials: A
authors.lastname: Bishop
authors.forename: Aaron
authors.initials: A
authors.lastname: Fleischauer
authors.forename: Chasisity B
authors.initials: CB
authors.lastname: Springs
authors.forename: Ha T
authors.initials: HT
authors.lastname: Nguyen
authors.forename: Tiffany G
authors.initials: TG
authors.lastname: Sheu
authors.forename: Katrina
authors.initials: K
authors.lastname: Sleeman
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
authors.forename: Larisa
authors.initials: L
authors.lastname: Gubareva
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007223:Infant; D009981:Influenza B virus / Q000235:genetics / Q000378:metabolism*; D007251:Influenza, Human / Q000188:drug therapy* / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009439:Neuraminidase / Q000235:genetics / Q000378:metabolism*; D009657:North Carolina / Q000453:epidemiology; D053139:Oseltamivir / Q000627:therapeutic use*; D013022:South Carolina / Q000453:epidemiology; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult
chemical_list: D053139:Oseltamivir; D009439:Neuraminidase