Seasonal Influenza Vaccine Impact on Pandemic H1N1 Vaccine Efficacy

Inhibition of RAN attenuates influenza a virus replication and nucleoprotein nuclear export

Nuclear export of the viral ribonucleoprotein (vRNP) is a critical step in the influenza A virus (IAV) life cycle and may be an effective target for the development of anti-IAV drugs. The host factor ras-related nuclear protein (RAN) is known to participate in the life cycle of several viruses, but its role in influenza virus replication remains unknown. In the present study, we aimed to determine the function of RAN in influenza virus replication using different cell lines and subtype strains. We found that RAN is essential for the nuclear export of vRNP, as it enhances the binding affinity of XPO1 toward the viral nuclear export protein NS2. Depletion of RAN constrained the vRNP complex in the nucleus and attenuated the replication of various subtypes of influenza virus. Using in silico compound screening, we identified that bepotastine could dissociate the RAN-XPO1-vRNP trimeric complex and exhibit potent antiviral activity against influenza virus both in vitro and in vivo. This study demonstrates the important role of RAN in IAV replication and suggests its potential use as an antiviral target.

Post-vaccination serum cytokines levels correlate with breakthrough influenza infections

Post-vaccination cytokine levels from 256 young adults who subsequently suffered breakthrough influenza infections were compared with matched controls. Modulation within the immune system is important for eliciting a protective response, and the optimal response differs according to vaccine formulation and delivery. For both inactivated influenza vaccine (IIV) and live attenuated influenza vaccines (LAIV) lower levels of IL-8 were observed in post-vaccination sera. Post-vaccination antibody levels were higher and IFN-γ levels were lower in IIV sera compared to LAIV sera. Subjects who suffered breakthrough infections after IIV vaccination had higher levels of sCD25 compared to the control group. There were differences in LAIV post-vaccination interleukin levels for subjects who subsequently suffered breakthrough infections, but these differences were masked in subjects who received concomitant vaccines. Wide variances, sex-based differences and confounders such as concomitant vaccines thwart the establishment of specific cytokine responses as a correlate of protection, but our results provide real world evidence that the status of the immune system following vaccination is important for successful vaccination and subsequent protection against disease.

Characteristics of Healthcare Workers Vaccinated against Influenza in the Era of COVID-19

Understanding the potential impact of COVID-19 on receiving influenza vaccination among healthcare workers (HCWs) is of utmost importance. The purposes of the present cross-sectional study were to describe the characteristics and to explore the predictors of receiving influenza vaccination among a large cohort of Italian HCWs in hospital settings. Information was collected through an anonymous questionnaire from December 2020 through January 2021. General and practice characteristics, perceived risk of seasonal influenza, attitudes towards efficacy and safety of influenza vaccination, and reasons behind the decision to be vaccinated against influenza were explored. Fewer than half (46.2%) of HCWs agreed that influenza is a serious illness and perceived the risk of getting infected with influenza, and concerns about the safety of the vaccination were significant positive predictors. Fewer than half of the respondents were not concerned at all about the efficacy (48.6%) and safety (49.8%) of influenza vaccination, and 51.9% reported that they have not received a seasonal influenza vaccine during the previous season. The most mentioned reason for receiving the influenza vaccine in the current season was that influenza and COVID-19 share some similar symptoms. Study results will aid policymakers in developing vaccination education programs, promotion of trust to address negative misconceptions, and to achieve future high coverage among this high-risk group.