A community cluster of influenza A(H3N2) virus infection with reduced susceptibility to baloxavir due to a PA E199G substitution in Japan, February to March 2023

A community cluster of influenza A(H3N2) caused by viruses with an E199G substitution in PA was detected in Nara, Japan, between February and March 2023. The three patients with these mutant viruses had not received antiviral treatment before specimen collection but patients in the same hospital had. The sequences of the mutant viruses were closely related, suggesting clonal spread in Nara. They showed reduced susceptibility to baloxavir in vitro; however, the clinical significance of the PA E199G substitution remains unclear.

Source: Eurosurveillance - September 28, 2023 Category: Infectious Diseases Authors: Emi Takashita, Seiichiro Fujisaki, Hiroko Morita, Shiho Nagata, Hideka Miura, Yuki Matsuura, Saya Yamamoto, Shoko Chiba, Yumiko Inoue, Iori Minami, Sayaka Yoshikawa, Seiko Yamazaki, Noriko Kishida, Kazuya Nakamura, Masayuki Shirakura, Shinji Watanabe and Source Type: research