BACKGROUND: Beginning from late 2011 and early 2012, increasing circulation of antigenically drifted influenza A/Victoria/361/2011-like H3N2 viruses within genotype 3 of the A/Victoria/208/2009 clade have been reported in multiple European countries and elsewhere. Whether these emerging viruses are associated with increased disease severity is unclear. OBJECTIVES: To report the clinical and virological findings of a moderately severe hospital outbreak of A/Victoria/361/2011-like viruses that occurred in November 2011 in Hong Kong. STUDY DESIGN: Clinical and virological hospital outbreak investigation. RESULTS: The outbreak occurred in an adult psychiatric ward in November 2011, a time well before the usual local seasonal influenza winter peak. Altogether, 7 patients and 1 healthcare-worker were affected (mean age, 47 [range, 34-61] years). The attack rates among patients and healthcare-workers were 33% (7/21) and 7% (1/15), respectively. Pneumonia developed in 38% (3/8) of cases; none had underlying immunocompromised conditions. High nasopharyngeal viral loads were detected. All cases responded to antiviral treatment. Multiple amino acid mutations with reference to earlier A(H3N2) vaccine strains were mapped to key antigenic sites on hemagglutinin; however, no critical mutations on receptor binding sites were detected. Viral sequence variations jeopardized the performance of molecular diagnostic assays. CONCLUSIONS: Severe disease and pneumonia occurred in a substantial proportion of non-immunocompromised adults in a hospital outbreak attributed to the emerging antigenically drifted A/Victoria/361/2011-like H3N2 viruses. Close monitoring of the transmission of this drift variant is required. Further studies are also necessary to determine virus virulence.
BACKGROUND: Beginning from late 2011 and early 2012, increasing circulation of antigenically drifted influenza A/Victoria/361/2011-like H3N2 viruses within genotype 3 of the A/Victoria/208/2009 clade have been reported in multiple European countries and elsewhere. Whether these emerging viruses are associated with increased disease severity is unclear. OBJECTIVES: To report the clinical and virological findings of a moderately severe hospital outbreak of A/Victoria/361/2011-like viruses that occurred in November 2011 in Hong Kong. STUDY DESIGN: Clinical and virological hospital outbreak investigation. RESULTS: The outbreak occurred in an adult psychiatric ward in November 2011, a time well before the usual local seasonal influenza winter peak. Altogether, 7 patients and 1 healthcare-worker were affected (mean age, 47 [range, 34-61] years). The attack rates among patients and healthcare-workers were 33% (7/21) and 7% (1/15), respectively. Pneumonia developed in 38% (3/8) of cases; none had underlying immunocompromised conditions. High nasopharyngeal viral loads were detected. All cases responded to antiviral treatment. Multiple amino acid mutations with reference to earlier A(H3N2) vaccine strains were mapped to key antigenic sites on hemagglutinin; however, no critical mutations on receptor binding sites were detected. Viral sequence variations jeopardized the performance of molecular diagnostic assays. CONCLUSIONS:Severe disease and pneumonia occurred in a substantial proportion of non-immunocompromised adults in a hospital outbreak attributed to the emerging antigenically drifted A/Victoria/361/2011-like H3N2 viruses. Close monitoring of the transmission of this drift variant is required. Further studies are also necessary to determine virus virulence.
Authors: Timothy M Uyeki; Henry H Bernstein; John S Bradley; Janet A Englund; Thomas M File; Alicia M Fry; Stefan Gravenstein; Frederick G Hayden; Scott A Harper; Jon Mark Hirshon; Michael G Ison; B Lynn Johnston; Shandra L Knight; Allison McGeer; Laura E Riley; Cameron R Wolfe; Paul E Alexander; Andrew T Pavia Journal: Clin Infect Dis Date: 2019-03-05 Impact factor: 9.079
Authors: Myint Tin Tin Htar; Anke L Stuurman; Germano Ferreira; Cristiano Alicino; Kaatje Bollaerts; Chiara Paganino; Ralf René Reinert; Heinz-Josef Schmitt; Cecilia Trucchi; Thomas Vestraeten; Filippo Ansaldi Journal: PLoS One Date: 2017-05-23 Impact factor: 3.240
Authors: Philippe Gautret; Gregory C Gray; Remi N Charrel; Nnanyelugo G Odezulu; Jaffar A Al-Tawfiq; Alimuddin Zumla; Ziad A Memish Journal: Lancet Infect Dis Date: 2014-09-01 Impact factor: 25.071