Co-circulation and persistence of multiple A/H3N2 influenza variants in China

Abstract

The spread of influenza A/H3N2 variants possessing the hemagglutinin 121 K mutation and the unexpectedly high incidence of influenza in the 2017–2018 northern hemisphere influenza season have raised serious concerns about the next pandemic. We summarized the national surveillance data of seasonal influenza in China and identified marked differences in influenza epidemics between northern and southern China, particularly the predominating subtype and the presence of an additional summer peak in southern China. Notably, a minor spring peak of influenza caused by a different virus subtype was also observed. We also revealed that the 3C.2a lineage was dominant from the summer of 2015 to the end of the 2015–2016 peak season in China, after which the 3C.2a2 lineage predominated despite the importation and co-circulation of the 121 K variants of 3C.2a1 and 3C.2a3 lineages at the global level. Finally, an analysis based on genetic distances revealed a delay in A/H3N2 vaccine strain update. Overall, our results highlight the complicated circulation pattern of seasonal influenza in China and the necessity for a timely vaccine strain update worldwide.

Life course exposures continually shape antibody profiles and risk of seroconversion to influenza

“…Our study has several limitations. First, we didn't include strain from Clade 2c.3a, which was co-circulating with A/HongKong/2014-like strain in the 2014-2015 season [30]. Our results seem to be robust as we found similar effects of immunity to previous exposures on the seroconversion to four recent strains (Table 1).…”

SARS-CoV-2 detection in patients with influenza-like illness

“…The ILI statistics and throat swab samples for this study were collected during the routine ILI surveillance of two national influenza sentinel hospitals in Wuhan. A patient was identified as an ILI case in the outpatient department of both hospitals if they had a sudden onset of a fever >38 °C as well as a cough or sore throat, according to the latest National Influenza Surveillance Plan 16 . The number of ILI cases and total outpatient numbers were collected weekly.…”

Dynamic PB2-E627K substitution of influenza H7N9 virus indicates the in vivo genetic tuning and rapid host adaptation

“…Most of the human cases had a history of direct exposure to or close contact with live poultry markets (LPMs) before disease onset, which implies a zoonotic origin of the virus ( 7 – 11 ), while only limited human-to-human transmission has been reported ( 12 ). However, the national surveillance on influenza in China reported the persistence of AIVs in the LPMs ( 13 ) and the sporadic human cases ( 14 ), indicating a continuous threat of the virus for public health ( 15 – 17 ) and even global biosecurity ( 18 , 19 ).…”