Intensive Care Admissions and Associated Severity of Influenza B Versus A During Influenza B Vaccine-mismatched Seasons

Impact of sex on humoral immunity with live influenza B virus vaccines in mice

Influenza B virus (FLUBV) poses a significant infectious threat, with frequent vaccine mismatch limiting its effectiveness. Our previous work investigated the safety and efficacy of modified live attenuated FLUBV vaccines with rearranged genomes (FluB-RAM and FluB-RANS) or a temperature-sensitive PB1 segment with a C-terminal HA tag (FluB-att). In this study, we compared the immune responses of female and male DBA/2J mice vaccinated with these vaccines, including versions containing a chimeric HA segment with an N-terminal IgA-inducing peptide (IGIP). Importantly, both recombinant viruses with and without IGIP remained genetically stable during egg passage. We found that introducing IGIP strengthened vaccine attenuation, particularly for FluB-RAM/IGIP. Prime-boost vaccination completely protected mice against lethal challenge with a homologous FLUBV strain. Notably, recombinant viruses induced robust neutralizing antibody responses (hemagglutination inhibition titers ≥40) alongside antibodies against NA and NP. Interestingly, female mice displayed a consistent trend of enhanced humoral and cross-reactive IgG and IgA responses against HA, NA, and NP compared to male counterparts, regardless of the vaccine used. However, the presence of IGIP generally led to lower anti-HA responses but higher anti-NA and anti-NP responses, particularly of the IgA isotype. These trends were further reflected in mucosal and serological responses two weeks after challenge, with clear distinctions based on sex, vaccine backbone, and IGIP inclusion. These findings hold significant promise for advancing the development of universal influenza vaccines.

Viral and Bacterial Respiratory Pathogens during the COVID-19 Pandemic in Israel

BACKGROUND

previous worldwide reports indicated a substantial short-term reduction in various respiratory infections during the early phase of the SARS-CoV-2 pandemic.

AIMS

exploring the long-term impact of the COVID-19 pandemic on respiratory pathogens.

METHODS

retrospective analysis of bacterial and viral positivity rate in respiratory samples, between 1 January 2017-30 June 2022 in a tertiary hospital in Jerusalem, Israel.

RESULTS

A decline in overall respiratory tests and positivity rate was observed in the first months of the pandemic. Respiratory isolations of Hemophilus influenza and Streptococcus pneumoniae were insignificantly affected and returned to their monthly average by November 2020, despite a parallel surge in COVID-19 activity, while Mycoplasma pneumoniae was almost eliminated from the respiratory pathogens scene. Each viral pathogen acted differently, with adenovirus affected only for few months. Human-metapneumovirus and respiratory-syncytial-virus had reduced activity for approximately a year, and influenza A virus resurged in November 2021 with the elimination of Influenza-B.

CONCLUSIONS

After an immediate decline in non-SARS-CoV-2 respiratory infections, each pathogen has a different pattern during a 2-year follow-up. These patterns might be influenced by intrinsic factors of each pathogen and different risk reduction behaviors of the population. Since some of these measures will remain in the following years, we cannot predict the timing of return to pre-COVID-19 normalcy.

FluB-RAM and FluB-RANS: Genome Rearrangement as Safe and Efficacious Live Attenuated Influenza B Virus Vaccines

Influenza B virus (IBV) is considered a major respiratory pathogen responsible for seasonal respiratory disease in humans, particularly severe in children and the elderly. Seasonal influenza vaccination is considered the most efficient strategy to prevent and control IBV infections. Live attenuated influenza virus vaccines (LAIVs) are thought to induce both humoral and cellular immune responses by mimicking a natural infection, but their effectiveness has recently come into question. Thus, the opportunity exists to find alternative approaches to improve overall influenza vaccine effectiveness. Two alternative IBV backbones were developed with rearranged genomes, rearranged M (FluB-RAM) and a rearranged NS (FluB-RANS). Both rearranged viruses showed temperature sensitivity in vitro compared with the WT type B/Bris strain, were genetically stable over multiple passages in embryonated chicken eggs and were attenuated in vivo in mice. In a prime-boost regime in naïve mice, both rearranged viruses induced antibodies against HA with hemagglutination inhibition titers considered of protective value. In addition, antibodies against NA and NP were readily detected with potential protective value. Upon lethal IBV challenge, mice previously vaccinated with either FluB-RAM or FluB-RANS were completely protected against clinical disease and mortality. In conclusion, genome re-arrangement renders efficacious LAIV candidates to protect mice against IBV.

Comparative efficacy assessment of antiviral alone and antiviral-antibiotic combination in prevention of influenza-B infection associated complications

OBJECTIVE

The study aimed to compare the efficacy of antiviral drug alone and antiviral-antibiotic combination therapy in prevention of complications associated with influenza B hospitalized patients.

METHOD

Laboratory confirmed influenza B hospitalized patients presented in emergency room after 48 hours of symptoms onset were identified and divided into two groups; Group-1 patients were initiated on Antiviral drug (oseltamivir) alone while Group-2 patients were initiated on Antiviral drug (oseltamivir) in combination with Antibiotic for at least 3 days. Patients were evaluated for different clinical outcomes among both treatment group.

RESULTS

A total of 153 and 131 patients were identified for Group-1 and Group-2, respectively. Clinical outcomes such as secondary bacterial infections (20.9%-vs-9.1%; P = 0.031), need of respiratory support (28.7%-vs-12.9%; P = 0.002), length of hospitalization stay (6.57-vs-4.95 days; P = <0.001), incidences of ICU admission (15.7%-vs-7.6%; P = 0.036), early clinical failure (32.6%-vs-16.1%; P = 0.01), and time to clinical stability (4.83-vs-4.1 days; P = 0.001) were found to be statistically less significant (P-value <0.05) for Group-2 patients.

CONCLUSION

Early initiation of antibiotic therapy in combination with oseltamivir was found to be more efficacious than oseltamivir alone in prevention of influenza B-associated complications especially in high-risk influenza patients.

Reverse genetics for influenza B viruses and recent advances in vaccine development

Influenza B virus is a respiratory pathogen that affects more severely the pediatric and elderly populations. There are two lineages of influenza B virus that seem to have differential predilection for age groups. Both lineages can co-circulate during the influenza season however one is usually more prominent than the other depending on the season. There are no defined indicators to predict which lineage will dominate in any given season. In recent years, the addition of viruses from both lineages to the seasonal influenza vaccine formulation has improved vaccine protection, although quadrivalent vaccines are not available worldwide. Reverse genetics has facilitated advancements in the field of vaccine development against influenza B virus. Different strategies have been explored showing promising results that could potentially lead to the development broadly protective influenza B virus vaccines.

Influenza and respiratory syncytial virus infections in the oldest-old continent

SARS-CoV-2 dramatically revealed the sudden impact of respiratory viruses in our lives. Influenza and respiratory syncytial virus (RSV) infections are associated with high rates of morbidity, mortality, and an important burden on healthcare systems worldwide, especially in elderly patients. The aim of this study was to identify severity predictors in the oldest-old admitted with influenza and/or RSV infections. This is a multicenter, retrospective study of all oldest-old patients (≥ 85 years old) admitted for laboratory-confirmed influenza and/or RSV infection in three tertiary hospitals in Portugal, Italy, and Cyprus over two consecutive winter seasons. The outcomes included the following: pneumonia on infection presentation, use of non-invasive ventilation (NIV), and in-hospital death (IHD). The association with possible predictors, including clinical features and type of virus infection, was assessed using uni- and multivariable analyses. A total of 251 oldest-old patients were included in the study. Pneumonia was evident in 32.3% (n = 81). NIV was implemented in 8.8% (n = 22), and IHD occurred in 13.9% (n = 35). Multivariable analyses revealed that chronic obstructive pulmonary disease (COPD) or asthma was associated with pneumonia (OR 1.86; 95% CI 1.02-3.43; p = 0.045). COPD or asthma (OR 4.4; 95% CI 1.67-11.6; p = 0.003), RSV (OR 3.12; 95% CI 1.09-8.92; p = 0.023), and influenza B infections (OR 3.77; 95% CI 1.06-13.5; p = 0.041) were associated with NIV use, respectively, while chronic kidney disease was associated with IHD (OR 2.50; 95% CI 1.14-5.51; p = 0.023). Among the oldest-old, chronic organ failure, such as COPD or asthma, and CKD predicted pneumonia and IHD, respectively, beyond the importance of viral virulence itself. These findings could impact on public health policies, such as fostering influenza immunization campaigns, home-based care programs, and end-of-life care. Filling knowledge gaps is crucial to set priorities and advise on transition model of care that best fits the oldest-old.

Predictors of mortality of influenza virus infections in a Swiss Hospital during four influenza seasons: Role of quick sequential organ failure assessment

BACKGROUND

Influenza infections have been associated with high morbidity. The aims were to determine predictors of mortality among patients with influenza infections and to ascertain the role of quick Sequential Organ Failure Assessment (qSOFA) in predicting poor outcomes.

METHODS

All adult patients with influenza infection at the Hospital of Jura, Switzerland during four influenza seasons (2014/15 to 2017/18) were included. Cepheid Xpert Xpress Flu/RSV was used during the first three influenza seasons and Cobas Influenza A/B and RSV during the 2017/18 season.

RESULTS

Among 1684 influenza virus tests performed, 441 patients with influenza infections were included (238 for influenza A virus and 203 for B). The majority of infections were community onset (369; 83.7%). Thirty-day mortality was 6.0% (25 patients). Multivariate analysis revealed that infection due to A virus (P 0.035; OR 7.1; 95% CI 1.1-43.8), malnutrition (P < 0.001; OR 25.0; 95% CI 4.5-138.8), hospital-acquired infection (P 0.003; OR 12.2; 95% CI 2.3-65.1), respiratory insufficiency (PaO₂/FiO₂ < 300) (P < 0.001; OR 125.8; 95% CI 9.6-1648.7) and pulmonary infiltrate on X-ray (P 0.020; OR 6.0; 95% CI 1.3-27.0) were identified as predictors of mortality. qSOFA showed a very good accuracy (0.89) equivalent to other more specific and burdensome scores such as CURB-65 and Pneumonia Severity Index (PSI).

CONCLUSION

qSOFA performed similarly to specific severity scores (PSI, CURB-65) in predicting mortality. Infection by influenza A virus, respiratory insufficiency and malnutrition were associated with worse prognosis.

Comparison of clinical outcomes of influenza A and B at the 2017-2018 influenza season: a cohort study

Influenza has significant morbidity and mortality. Some experts consider infection with influenza B as milder than that with influenza A. The objective of this study is to evaluate the outcomes of hospitalized patients with laboratory-confirmed influenza A or B in 2017–2018 influenza season. All hospitalized patients between October 2017 and April 2018 with laboratory-confirmed influenza A and B were included. The primary composite outcomes were pneumonia/myocarditis/encephalitis, mechanical ventilation, ICU admission, and 30-day mortality. Secondary outcomes were 30-/90-day mortality, length of hospital stay, and readmission rates. The study included 201 influenza A and 325 influenza B. For the primary composite outcome, no significant difference was demonstrated between influenza A and B. Rates of mortality were similar at 30 and 90 days. Influenza A had higher pneumonia rates and mechanical ventilation. On multivariate analysis, higher Charlson’s score, hypoalbuminemia, and vasopressor use were associated with 30-day mortality, while infection with either influenza A or B was not. Influenza A was associated with higher pneumonia and mechanical ventilation rates. However, influenza B resulted with similar 30-day mortality rate as influenza A.

Development and evaluation of a conventional RT-PCR for differentiating emerging influenza B/Victoria lineage viruses with hemagglutinin amino acid deletion from B/Yamagata lineage viruses

BACKGROUND

Recent influenza B/Victoria lineage viruses contain amino acid deletions at positions 162 to 164 of the haemagglutinin (HA) protein. These amino acid deletions have affected the detection of B/Victoria lineage viruses by the lineage-specific conventional reverse-transcription polymerase chain reaction (RT-PCR) that was recommended by World Health Organization (WHO).

OBJECTIVES

We aimed to develop and evaluate a novel lineage-specific RT-PCR for rapid differentiation of the contemporary B/Victoria lineage from B/Yamagata lineage viruses.

STUDY DESIGN

Primers of our in-house RT-PCR were designed to avoid amino acid positions 162 to 164 and to target conserved regions of the HA gene that are specific for B/Victoria and B/Yamagata lineage viruses. Our in-house RT-PCR and WHO RT-PCR were evaluated using influenza B positive clinical specimens or virus culture isolates. Influenza B virus lineage was confirmed by Sanger sequencing.

RESULTS

A total of 105 clinical specimens or virus culture isolates were retrieved, including 83 with B/Victoria lineage and 22 with B/Yamagata lineage viruses. Our in-house RT-PCR correctly identified B/Victoria lineage viruses in all 83 samples, including 82 samples with double or triple amino acid deletion in the HA protein. Conversely, the WHO lineage-specific conventional RT-PCR failed to detect any of the 82 samples with HA amino acid deletions. For the 22 samples with B/Yamagata lineage viruses, both RT-PCR assays have correctly identified B/Yamagata lineage in all samples.

CONCLUSIONS

Our novel lineage-specific RT-PCR has successfully detected all contemporary B/Victoria lineage viruses with amino acid deletions in HA. This protocol is especially useful for laboratories without the equipment for real-time PCR.

Quadrivalent versus trivalent influenza vaccine: clinical outcomes in two influenza seasons, historical cohort study

OBJECTIVES

The quadrivalent influenza vaccine (QIV) contains two influenza B antigens (one of each B lineage), while the trivalent vaccine (TIV) contains solely one. As a result, a mismatch between the circulating B lineage and the lineage in the TIV occurs frequently. We aimed to compare the frequency of clinically significant outcomes in a large cohort of vaccinees receiving either TIV or QIV.

METHODS

Historical cohort study of all inactivated influenza vaccinees (aged 3 years and older) in a Health Maintenance Organization insuring 1.2 million individuals, over two influenza seasons in which both vaccines were provided non-selectively. Primary outcome was hospital admissions during the influenza season. Multivariate analysis was performed using logistic regression to adjust for relevant covariates.

RESULTS

Our cohort included 150 518 and 168 296 vaccinees in the first (S1) and second season (S2), respectively. The two influenza seasons were characterized by high Influenza B activity. Of those vaccinated with QIV, 2074 of 49 726 (4.2%) and 6563 of 121 741 (5.4%) were hospitalized compared with 7378 of 100 792 (7.3%) and 3372 of 46 555 (7.2%) of those vaccinated with TIV (S1 and S2, respectively). After multivariate analysis adjusting for several covariates (gender, age, socioeconomic status, chronic morbidity, timing of vaccination), compared with TIV recipients, QIV vaccinees had lower odds for hospitalization (OR = 0.92, 95% CI 0.87-0.98 and OR = 0.89, 95% CI 0.85-0.93) or emergency department visit (OR = 0.91, 95% CI 0.87-0.95 and OR = 0.84, 95% CI 0.81-0.87) in S1 and S2, respectively (p < 0.001). Lower odds of mortality and influenza-like illness were also observed in S2 (OR = 0.61, 95% CI 0.50-0.75 and OR = 0.92, 95% CI 0.90-0.95, respectively).

CONCLUSIONS

In seasons with relatively high influenza B activity, QIV appeared more protective than TIV in Israel.