Characterization of a 2016-2017 Human Seasonal H3 Influenza A Virus Spillover Now Endemic to U.S. Swine

H3.2010.2 is a new phylogenetic clade of H3N2 circulating in swine that became established after the spillover of a human seasonal H3N2 from the 2016–2017 influenza season. The novel H3.2010.2 transmitted and adapted to the swine host and demonstrated reassortment with internal genes from strains endemic to pigs, but it maintained human-like HA and NA.

Relative Effectiveness of Cell-Cultured versus Egg-Based Seasonal Influenza Vaccines in Preventing Influenza-Related Outcomes in Subjects 18 Years Old or Older: A Systematic Review and Meta-Analysis

Avian mutations in vaccine strains obtained from embryonated eggs could impair vaccine effectiveness. We performed a systematic review and meta-analysis of the adjusted relative vaccine effectiveness (arVE) of seed cell-cultured influenza vaccines (ccIV) compared to egg-based influenza vaccines (eIV) in preventing laboratory-confirmed influenza related outcomes (IRO) or IRO by clinical codes, in subjects 18 and over. We completed the literature search in January 2021; applied exclusion criteria, evaluated risk of bias of the evidence, and performed heterogeneity, publication bias, qualitative, quantitative and sensitivity analyses. All estimates were computed using a random approach. International Prospective Register of Systematic Reviews, CRD42021228290. We identified 12 publications that reported 26 adjusted arVE results. Five publications reported 13 laboratory confirmed arVE and seven reported 13 code-ascertained arVE. Nine publications with 22 results were at low risk of bias. Heterogeneity was explained by season. We found a significant 11% (8 to 14%) adjusted arVE favoring ccIV in preventing any IRO in the 2017–2018 influenza season. The arVE was 3% (−2% to 7%) in the 2018–2019 influenza season. We found moderate evidence of a significant advantage of the ccIV in preventing IRO, compared to eIV, in a well-matched A(H3N2) predominant season.

Droplet precautions on-site (DroPS) during the influenza season 2018/2019: a possible alternative to single room isolation for respiratory viral infections

Background The guideline-driven and widely implemented single room isolation strategy for respiratory viral infections (RVI) such as influenza or respiratory syncytial virus (RSV) can lead to a shortage of available hospital beds. We discuss our experience with the introduction of droplet precautions on-site (DroPS) as a possible alternative. Methods During the 2018/19 influenza season we introduced DroPS on several wards of a single tertiary care center, while other wards maintained the traditional single room isolation strategy. On a daily basis, we evaluated patients for the development of respiratory symptoms and screened those with a clinical diagnosis of hospital-acquired respiratory viral infection (HARVI) for influenza/RSV by molecular rapid test. If negative, it was followed by a multiplex respiratory virus PCR. We report the concept of DroPS, the feasibility of the strategy and the rate of microbiologically confirmed HARVI with influenza or RSV infection on the DroPS wards compared to wards using the traditional single room isolation strategy. Results We evaluated all hospitalised patients at risk for a HARVI, 741 (72%) on the DroPS wards and 293 (28%) on the regular wards. The hospital-acquired infection rate with influenza or RSV was 2/741 (0.3%; 1× influenza A, 1× RSV) on the DroPS wards and 2/293 (0.7%; 2× influenza A) on the regular wards. Conclusions Droplet precautions on-site (DroPS) may be a simple and potentially resource-saving alternative to the standard single room isolation strategy for respiratory viral infections. Further studies in a larger clinical context are needed to document its safety.

Cost-effectiveness of quadrivalent versus trivalent inactivated influenza vaccines for the Portuguese elderly population

Background Quadrivalent Inactivated Vaccine (QIV) is expected to replace Trivalent Inactivated Vaccine (TIV) over time. In Portugal, TIV is free of charge for risk groups, which include older adults. In its turn, QIV – which provides broader protection as it includes an additional lineage B strain – was introduced in Portugal in October 2018, but only from the influenza season 2019/20 was provided free of charge for the risk groups. This study evaluates the cost-effectiveness of switching from TIV to QIV from the National Health Service perspective in the Portuguese elderly mainland population (≥65 years old). Methods A decision tree model was developed to compare TIV and QIV, based on Portuguese hospitalization data for the 2015/16 influenza season. The primary health economic outcome under consideration was the Incremental Cost-Effectiveness Ratio (ICER). In addition, a one-Way Sensitivity Analysis was performed to evaluate the impact of model parameters on the ICER; Probabilistic Sensitivity Analysis was also carried out to analyze the robustness of the base case results. Results The high cost of QIV (approximately three times the cost of TIV) would lead to a total increment of 5,283,047 €, and the resulting ICER would be 26,403,007€/QALY, mainly above the usual willingness-to-pay threshold. Conclusions From the National Health Service perspective, our findings reveal that QIV is not cost-effective for the Portuguese elderly population due to the high cost. If the QIV costs were the same as the TIV, then QIV would be cost-effective.

Life-Threatening Necrotizing Pneumonia with Panton–Valentine Leukocidin-Producing, Methicillin-Sensitive Staphylococcus aureus in a Healthy Male Co-Infected with Influenza B

A previously healthy male was rushed into a hospital critically ill with confusion, sepsis, and acute respiratory distress syndrome only 43 h after having a normal chest X-ray and with blood samples showing only minimally elevated C-reactive protein. Two days earlier, the patient had returned to his home country, the Faroe Islands, from a 10-day work trip aboard a Scandinavian ship in Colombia. The diagnosis turned out to be an influenza B infection and necrotizing pneumonia with Panton–Valentine leukocidin (PVL)-producing methicillin-sensitive Staphylococcus aureus (MSSA). It was influenza season in Colombia but not in the Faroe Islands. The frequency of MSSA with PVL-encoding genes among pediatric infection patients is very low in the Kingdom of Denmark and Faroe Islands and very high in Colombia, and the frequency generally varies highly by region. The patient in this case now suffers severe sequelae from the infection. With this case, we would like to remind clinicians of this rare but severe condition. PVL-producing S. aureus pneumonia should be considered in critically ill, previously healthy patients, especially during influenza season and if the patient has been traveling in countries with high frequencies of PVL-producing S. aureus.

Estimating the impact of low influenza activity in 2020 on population immunity and future influenza seasons in the United States

Backgrounds Influenza activity in the 2020-21 season was remarkably low, likely due to implementation of public health preventive measures such as social distancing, mask-wearing, and school closure. With waning immunity, the impact of low influenza activity in the 2020-21 on the following season is unknown. Method We built a multi-strain compartmental model that captures immunity over multiple influenza seasons in the US. Compared to the counterfactual case, where influenza activity remained at the normal level in 2020-21, we estimated the change in the number of hospitalizations when the transmission rate was decreased by 20% in 2020-21. We varied the level of vaccine uptake and effectiveness in 2021-22. We measured the change in population immunity over time by varying the number of seasons with lowered influenza activity. Results With the lowered influenza activity in 2020-21, the model estimated 102,000 [95% CI: 57,000-152,000] additional hospitalizations in 2021-22, without changes in vaccine uptake and effectiveness. The estimated changes in hospitalizations varied depending on the level of vaccine uptake and effectiveness in the following year. Achieving 50% increase in vaccine coverage was necessary to avert the expected increase in hospitalization in the next influenza season. If the low influenza activity were to continue over several seasons, population immunity would remain low during those seasons, with 48% the population susceptible to influenza infection. Conclusion Our study projecteda large compensatory influenza season in 2021-22 due to a light season in 2020-21. However, higher influenza vaccine uptake would reduce this projected increase in influenza.

Comparative Evaluation of Allplex Respiratory Panels 1, 2, 3, and BioFire FilmArray Respiratory Panel for the Detection of Respiratory Infections

Multiplex nucleic acid amplification assays that simultaneously detect multiple respiratory pathogens in a single nasopharyngeal swab (NPS) specimen are widely used for rapid clinical diagnostics. We evaluated Allplex Respiratory Panel (RP) 1, 2, 3, and the BioFire FilmArray RP assay for detecting respiratory pathogens from NPS specimens. In all, 181 NPS specimens obtained from patients suspected of having respiratory infections during the non-influenza season (August–December 2019) were included. The Allplex RP 1, 2, and 3 detected 154 samples positive for respiratory viruses, whereas the BioFire FilmArray detected viruses in 98 samples. Co-infection with two or more viruses was detected in 41 and 17 NPS specimens by Allplex RP and the BioFire FilmArray RP, respectively. For adenoviruses, Allplex RP 1 detected 31 specimens, compared to 34 by the BioFire FilmArray. In all, 64 NPS specimens were positive for human enterovirus (HEV) and human rhinovirus (HRV) on the Allplex RP, in contrast to 39 HEV/HRV on the BioFire FilmArray. The parainfluenza virus (PIV-1–4) detection rate differed between the two systems. Most discrepant results were observed for NPS specimens with high cycle threshold values obtained by Allplex RP. This study showed concordant performance of the Allplex RP 1, 2, 3, and the BioFire FilmArray RP for the simultaneous detection of multiple respiratory viruses.

The Potential Benefits of the Influenza Vaccination on COVID-19 Mortality Rate—A Retrospective Analysis of Patients in Poland

In this study, we used publicly available data from the Centrum e-Zdrowia (CeZ) Polish Databank proposing a possible correlation between influenza vaccination and mortality due to COVID-19. We limited our search to the patients with positive COVID‑19 laboratory tests from 1 January 2020 to 31 March 2021 and who filled a prescription for any influenza vaccine during the 2019–2020 influenza season. In total, we included 116,277 patients and used a generalized linear model to analyze the data. We found out that patients aged 60+ who received an influenza vaccination have a lower probability of death caused by COVID-19 in comparison to unvaccinated, and the magnitude of this difference grows with age. For people below 60 years old, we did not observe an influence of the vaccination. Our results suggest a potential protective effect of the influenza vaccine on COVID-19 mortality of the elderly. Administration of the influenza vaccine before the influenza season would reduce the burden of increased influenza incidence, the risk of influenza and COVID‑19 coinfection and render the essential medical resources accessible to cope with another wave of COVID-19. To our knowledge, this is the first study showing a correlation between influenza vaccination and the COVID-19 mortality rate in Poland.

Relative Effectiveness of Cell-Cultured versus Egg-Based Seasonal Influenza Vaccines in Preventing Influenza-Related Outcomes in Subjects 18 Years Old or Older: A Systematic Review and Meta-Analysis

Avian mutations in vaccine strains obtained from embryonated eggs could impair vaccine effec-tiveness. We performed a systematic review and meta-analysis of the adjusted relative vaccine effectiveness (arVE) of seed cell-cultured influenza vaccines (ccIV) compared to egg-based influ-enza vaccines (eIV) in preventing laboratory-confirmed influenza related outcomes (IRO) or IRO by clinical codes, in subjects 18 and over. We completed the literature search in January 2021; ap-plied exclusion criteria, evaluated risk of bias of the evidence, and performed heterogeneity, pub-lication bias, qualitative, quantitative and sensitivity analyses. All estimates were computed us-ing a random approach. International Prospective Register of Systematic Reviews, CRD42021228290. We identified 12 publications that reported 26 adjusted arVE results. Five publications reported 13 laboratory confirmed arVE and seven reported 13 code-ascertained arVE. Nine publications with 22 results were at low risk of bias. Heterogeneity was explained by season and risk of bias. We found a significant 11% (8 to 14%) adjusted arVE favoring ccIV in preventing any IRO in the 2017-2018 influenza season. The arVE was 3% (-01 to 7%) in the 2018-2019 influenza season. We found moderate evidence of a significant advantage of the ccIV in preventing IRO, compared to eIV, in a well-matched A(H3N2) predominant season.