Eurosurv. Influenza A(H3N2) virus exhibiting reduced susceptibility to baloxavir due to a polymerase acidic subunit I38T substitution detected from a

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[h=2]Influenza A(H3N2) virus exhibiting reduced susceptibility to baloxavir due to a polymerase acidic subunit I38T substitution detected from a hospitalised child without prior baloxavir treatment, Japan, January 2019

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• Emi Takashita[SUP]1[/SUP], Chiharu Kawakami[SUP]2[/SUP], Rie Ogawa[SUP]1[/SUP], Hiroko Morita[SUP]1[/SUP], Seiichiro Fujisaki[SUP]1[/SUP], Masayuki Shirakura[SUP]1[/SUP], Hideka Miura[SUP]1[/SUP], Kazuya Nakamura[SUP]1[/SUP], Noriko Kishida[SUP]1[/SUP], Tomoko Kuwahara[SUP]1[/SUP], Akira Ota[SUP]3[/SUP], Hayato Togashi[SUP]3[/SUP], Ayako Saito[SUP]4[/SUP], Keiko Mitamura[SUP]5[/SUP], Takashi Abe[SUP]6[/SUP], Masataka Ichikawa[SUP]7[/SUP], Masahiko Yamazaki[SUP]8[/SUP], Shinji Watanabe[SUP]1[/SUP], Takato Odagiri[SUP]1[/SUP]

The cap-dependent endonuclease inhibitor baloxavir marboxil became available in Japan in March 2018 for the treatment of influenza virus infection in patients aged 12 years and older and children younger than 12 years weighing at least 10 kg. Between October 2018 and January 2019, baloxavir was supplied to medical institutions that together serve ca 5.5 million people. In December 2018, we detected influenza A(H3N2) viruses exhibiting reduced susceptibility to baloxavir from baloxavir-treated children aged 6 and 7 years [1]. These viruses possessed an I38T substitution in the polymerase acidic subunit (PA), which confers reduced susceptibility to baloxavir [2]. We subsequently increased nationwide monitoring of the baloxavir susceptibility of circulating influenza viruses, irrespective of antiviral treatment [3].

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full article

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2019.24.12.1900170