Phylogenetic evidence from the recent resurgence of high-pathogenicity avian influenza (HPAI) virus subtype H5N1, clade 2.3.4.4b, observed in European wild birds and poultry since October 2021, suggests at least two different and distinct reservoirs. We propose contrasting hypotheses for this emergence: (i) resident viruses have been maintained, presumably in wild birds, in northern Europe throughout the summer of 2021 to cause some of the outbreaks that are part of the most recent autumn/winter 2021 epizootic, or (ii) further virus variants were reintroduced by migratory birds, and these two sources of reintroduction have driven the HPAI resurgence.

Influenza virus infection remains one of the largest disease burdens on humans. Influenza-associated bacterial co-infections contribute to severe disease and mortality during pandemic and seasonal influenza episodes. The mechanisms of severe morbidity following influenza-bacteria co-infections mainly include failure of an antibacterial immune response and pathogen synergy. Moreover, failure to resume function and tolerance might be one of the main reasons for excessive mortality. In this review, recent advances in the study of mechanisms of severe disease, caused by bacterial co-infections following influenza virus pathogenesis, are summarized. Therefore, understanding the synergy between viruses and bacteria will facilitate the design of novel therapeutic approaches to prevent mortality associated with bacterial co-infections.

Theranostic systems by integrating the tumor imaging and tumor therapeutic capabilities into one platform have attracted numerous attentions from worldwide researchers. Despite the great developments, their clinical application is still in the nascent stage, owing to the unsatisfied imaging quality and limited therapeutic efficacy. Fortunately, the emerging of aggregation‐induced emission (AIE) molecules with unique fluorescence property offers an opportunity to solve the imaging problem. Besides, further utilizing the tumor microenvironments and external triggers to design the stimuli‐responsive imaging‐guided therapy could enhance the therapeutic efficacy and reduce the side effects. In this review, the advancements in stimuli‐responsive theranostic systems with AIE characteristics are summarized. Theranostic systems are first classified according to their treatment modes, and then subdivided based on various stimuli, including pH, redox, enzyme, and light. In each section, the design strategies and application examples are introduced. At last, the current state of the art, limitations, as well as prospects are also discussed.

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