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Abstract Background Influenza A viruses have undergone rapid evolution with virulent; however, complete and comprehensive data on gene evolution and amino acid variation of HA and NA in immunosuppressed patients was few. In this study, we analysed molecular epidemiology and evolution of influenza A viruses in immunosuppressed population, and immunocompetent population were used as controls. Methods Full sequences of HA and NA of A(H1N1)pdm09 and A(H3N2) were acquired through reverse transcription-polymerase chain reaction (RT-PCR). HA and NA genes were sequenced using the Sanger method and phylogenetically analysed using ClustalW 2.10 and MEGA software version 11.0. Results During the 2018–2020 influenza seasons, 54 immunosuppressed and 46 immunocompetent inpatients screened positive for influenza A viruses by using the quantitative real-time PCR (qRT-PCR) were enrolled. 27 immunosuppressed and 23 immunocompetent nasal swab or bronchoalveolar lavage fluid samples were randomly selected and sequenced using the Sanger method. A(H1N1)pdm09 were detected in 15 samples and the remaining 35 samples were A(H3N2) positive. By analyzing the HA and NA gene sequences of these virus strains, we found that all A(H1N1)pdm09 viruses shared high similarities to each other and the HA and NA genes of these viruses exclusively belonged to subclade 6B.1A.1. Some NA genes of A(H3N2) viruses were not in the same clade as those of A/Singapore/INFIMH-16-0019/2016 and A/Kansas/14/2017, which may have led to A(H3N2) being the dominant strain in the 2019–2020 influenza season. Both A(H1N1)pdm09 and A(H3N2) viruses showed similar evolutionary lineages patterns of HA and NA between immunosuppressed and immunocompetent patients. Compared with the vaccine strains, there were no statistically significant of HA and NA genes and amino acid sequences of influenza A viruses in immunosuppressed and immunocompetent patients. However, the oseltamivir resistance substitution of NA-H275Y and R292K have been observed in immunosuppressed patients. Conclusions A(H1N1)pdm09 and A(H3N2) viruses showed similar evolutionary lineages patterns of HA and NA between immunosuppressed and immunocompetent patients. Both immunocompetent and immunosuppressed patients have some key substitutions, which should be of note monitored, especially those with potential to affect the viral antigen.

Abstract Background Compared with immunocompetent patients, immunosuppressed patients have higher morbidity and mortality, a longer duration of viral shedding, more frequent complications, and more antiviral resistance during influenza infections. However, few data on this population in China have been reported. We analysed the clinical characteristics, effects of antiviral therapy, and risk factors for admission to the intensive care unit (ICU) and death in this population after influenza infections and explored the influenza vaccination situation for this population. Methods We analysed 111 immunosuppressed inpatients who were infected with influenza virus during the 2015–2020 influenza seasons. Medical data were collected through the electronic medical record system and analysed. Univariate analysis and multivariate logistics analysis were used to identify risk factors. Results The most common cause of immunosuppression was malignancies being treated with chemotherapy (64.0%, 71/111), followed by haematopoietic stem cell transplantation (HSCT) (23.4%, 26/111). The most common presenting symptoms were fever and cough. Dyspnoea, gastrointestinal symptoms and altered mental status were more common in HSCT patients than in patients with immunosuppression due to other causes. Approximately 14.4% (16/111) of patients were admitted to the ICU, and 9.9% (11/111) of patients died. Combined and double doses of neuraminidase inhibitors did not significantly reduce the risk of admission to the ICU or death. Risk factors for admission to the ICU were dyspnoea, coinfection with other pathogens and no antiviral treatment within 48 h. The presence of dyspnoea and altered mental status were independently associated with death. Only 2.7% (3/111) of patients less than 12 months old had received a seasonal influenza vaccine. Conclusion Fever and other classic symptoms of influenza may be absent in immunosuppressed recipients, especially in HSCT patients. Conducting influenza virus detection at the first presentation seems to be a good choice for early diagnosis. Clinicians should pay extra attention to immunosuppressed patients with dyspnoea, altered mental status, coinfection with other pathogens and no antiviral treatment within 48 h because these patients have a high risk of severe illness. Inactivated influenza vaccines are recommended for immunosuppressed patients.

Abstract Background Influenza A(H1N1)pdm09 viruses have undergone rapid evolution, and in recent years the complementary and antagonistic effects of HA and NA have gathered more attentions; however, the effects of co-occurring mutations in HA and NA on the patients’ clinical characteristics are still poorly understood. In this study, we analyzed molecular epidemiology and evolution of A(H1N1) pdm09, explored co-occurring mutations of HA and NA, and investigated effect of co-occurring mutations on patients’ clinical features. Methods A(H1N1)pdm09 was confirmed by reverse transcription-polymerase chain reaction. HA and NA genes were sequenced and phylogenetically analyzed. Clinical characteristics of the co-occurring mutations were analyzed statistically. Results By analyzing the HA and NA gene sequences of 33 A(H1N1)pdm09 viruses during the 2015–2017 influenza season, we found that all the viruses shared high similarities to each other and the HA genes of these viruses exclusively belonged to subclade 6B.1A. Several unreported substitutions in HA and NA proteins were observed, furthermore, co-occurring mutations of HA-V169T, A278S, E508G, D518E and NA-V67I were detected in 30.3% (10/33) A(H1N1)pdm09 virus strains when comparing with vaccine strains A/California/07/2009 and A/Michigan/45/2015 (H1N1). Sore throat was significantly associated with co-occurring mutations in HA and NA of A(H1N1)pdm09 (χ2, P

Abstract Background Respiratory variations in the inferior vena cava diameter (ΔIVCD) have been studied extensively with respect to their value in predicting fluid responsiveness, but the results are conflicting. The aim of this meta-analysis was to explore the value of ΔIVCD for predicting fluid responsiveness in patients with circulatory shock receiving mechanical ventilation. Methods PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched up to June 2017. The diagnostic OR (DOR), sensitivity, and specificity were calculated. The summary ROC curve was estimated, and the area under the ROC curve (AUROC) was calculated. Results Overall, 603 patients were included in this review, 324 (53.7%) of whom were fluid-responsive. The cutoff values of ΔIVCD varied across studies, ranging from 8% to 21%. Heterogeneity between studies was assessed with an overall Q = 0.069, I 2 = 0%, and P = 0.483. The pooled sensitivity and specificity for the overall population were 0.69 (95% CI, 0.51–0.83) and 0.80 (95% CI, 0.66–0.89), respectively. The DOR was 9.28 (95% CI, 2.33–36.98). AUROCs were reported in five studies. Overall, the pooled AUROC was 0.82 (95% CI, 0.79–0.85). Conclusions The findings of this study suggest that the ΔIVCD performed moderately well in predicting fluid responsiveness in patients with circulatory shock receiving mechanical ventilation.