Evolutionary pattern of reemerging influenza B/Victoria lineage viruses in São Paulo, Brazil, 1996-2012: Implications for vaccine composition strategy

Differentiation of influenza B lineages circulating in different regions of Brazil, 2014 – 2016, using molecular assay

Background

Two antigenically and genetically distinct lineages of influenza B viruses (B/Victoria and B/Yamagata) have been co-circulating worldwide since 2002. Virological surveillance is essential to differentiate between both lineages with a view to the annual updating of the B component for the trivalent or quadrivalent influenza vaccine composition.

Methods

The samples analyzed in the present study were collected by influenza sentinel units located in the Southeast, Midwest, North, and Northeast regions of Brazil, part of the National Influenza Virus Surveillance Network, coordinated by the Ministry of Health of Brazil. A total of 870 influenza B positive samples by reverse transcription real – time polymerase chain reaction (RT-qPCR), collected during 2014, 2015, and 2016 influenza seasons, were submitted to the influenza B lineage genotyping panel for characterization as B/Yamagata or Victoria lineages using RT-qPCR.

Results

Of the 197 samples analyzed in 2014, a total of 160 (81 %) corresponded to the B/Yamagata lineage, 19 (10 %) to the B/Victoria lineage, and 18 (9 %) to indeterminate lineages. Of the 190 samples analyzed in 2015, a total of 124 (65 %) corresponded to the B/Yamagata lineage; 55 (29 %) to the B/Victoria lineage, whereas 11 (6 %) were of indeterminate lineages. Of the 483 samples analyzed in 2016, a total of 297 (62 %) corresponded to the B /Victoria lineage; 174 (36 %) to the B/Yamagata lineage and 12 (2 %) to indeterminate lineages. This cross-sectional study revealed influenza B virus (IBV) infection in all age groups, and among them, the highest prevalence was observed in individuals between 11 and 49 years of age Our findings demonstrate the match between influenza B virus lineages recommended by the World Health Organization (WHO) for the trivalent vaccine composition to be used in the Southern Hemisphere (SH) and the predominant circulating viruses during the 2014, 2015, and 2016 seasons.

Vaccine Mismatches, Viral Circulation, and Clinical Severity Patterns of Influenza B Victoria and Yamagata Infections in Brazil over the Decade 2010-2020: A Statistical and Phylogeny-Trait Analyses

Worldwide, infections by influenza viruses are considered a major public health challenge. In this study, influenza B vaccine mismatches and clinical aspects of Victoria and Yamagata infections in Brazil were assessed. Clinical samples were collected from patients suspected of influenza infection. In addition, sociodemographic, clinical, and epidemiological information were collected by the epidemiological surveillance teams. Influenza B lineages were determined by real-time RT-PCR and/or Sanger sequencing. In addition, putative phylogeny−trait associations were assessed by using the BaTS program after phylogenetic reconstruction by a Bayesian Markov Chain Monte Carlo method (BEAST software package). Over 2010−2020, B/Victoria and B/Yamagata-like lineages co-circulated in almost all seasonal epidemics, with B/Victoria predominance in most years. Vaccine mismatches between circulating viruses and the trivalent vaccine strains occurred in five of the eleven seasons (45.5%). No significant differences were identified in clinical presentation or disease severity caused by both strains, but subjects infected by B/Victoria-like viruses were significantly younger than their B/Yamagata-like counterparts (16.7 vs. 31.4 years, p < 0.001). This study contributes to a better understanding of the circulation patterns and clinical outcomes of B/Victoria- and B/Yamagata-like lineages in Brazil and advocate for the inclusion of a quadrivalent vaccine in the scope of the Brazilian National Immunization Program.

Influenza B viral load analysis in patients with acute respiratory infection from a tertiary hospital in Brazil

Currently, 2 genotypes of Influenza B viruses (IFB) are cocirculating in humans: Victoria (VIC) and Yamagata (YAM). Infection and viral load (VL) were analyzed in 105 genotyped IFB (59 VIC and 46 YAM) out of 3452 respiratory samples from immunodepressed (ID), immunocompetent (IC) including outpatients (OP) and hospitalized patients (HP) attended during 2001-2013 at São Paulo Hospital. VL (Log₁₀ RNA copies/mL) calculation was possible in 78 samples (47 VIC, 31 YAM). The age group of 12 to 18 years presented the highest detection (14.13%). Rates of infection among groups were of 3.67% (IC), 1.68% (ID), 3.50% (OP), 0.6% (HP), and VLs varied from 2.8 to 10.13 with no difference regarding age, immune status, and disease severity. From 10 OP vaccinated against influenza, 8 (7 children, 1 ID) received a matching strain shot (VIC), and 2 a monovalent influenza A H1N1pdm09. Those patients presented a VL of 6.31 ± 1.62 (mean ± SD). IFB infection rates follow an age pattern, but VL seems not to be related to frequency or clinical outcome. IFB patients with previous immunization could point to some protection for VIC infections since there was no HP. Other immunological aspects, such as lineage infection immune priming, previous infections, and vaccinations, should be further investigated.

The epidemiological signature of influenza B virus and its B/Victoria and B/Yamagata lineages in the 21st century

We describe the epidemiological characteristics, pattern of circulation, and geographical distribution of influenza B viruses and its lineages using data from the Global Influenza B Study. We included over 1.8 million influenza cases occurred in thirty-one countries during 2000–2018. We calculated the proportion of cases caused by influenza B and its lineages; determined the timing of influenza A and B epidemics; compared the age distribution of B/Victoria and B/Yamagata cases; and evaluated the frequency of lineage-level mismatch for the trivalent vaccine. The median proportion of influenza cases caused by influenza B virus was 23.4%, with a tendency (borderline statistical significance, p = 0.060) to be higher in tropical vs. temperate countries. Influenza B was the dominant virus type in about one every seven seasons. In temperate countries, influenza B epidemics occurred on average three weeks later than influenza A epidemics; no consistent pattern emerged in the tropics. The two B lineages caused a comparable proportion of influenza B cases globally, however the B/Yamagata was more frequent in temperate countries, and the B/Victoria in the tropics (p = 0.048). B/Yamagata patients were significantly older than B/Victoria patients in almost all countries. A lineage-level vaccine mismatch was observed in over 40% of seasons in temperate countries and in 30% of seasons in the tropics. The type B virus caused a substantial proportion of influenza infections globally in the 21^st century, and its two virus lineages differed in terms of age and geographical distribution of patients. These findings will help inform health policy decisions aiming to reduce disease burden associated with seasonal influenza.

Influenza B associated paediatric acute respiratory infection hospitalization in central vietnam

Background

Influenza B is one of the major etiologies for acute respiratory infections (ARI) among children worldwide; however, its clinical‐epidemiological information is limited. We aimed to investigate the hospitalization incidence and clinical‐epidemiological characteristics of influenza B‐associated paediatric ARIs in central Vietnam.

Methods

We collected clinical‐epidemiological information and nasopharyngeal swabs from ARI children hospitalized at Khanh Hoa General Hospital, Nha Trang, Vietnam from February 2007 through June 2013. Nasopharyngeal samples were screened for 13 respiratory viruses using Multiplex‐PCRs. Influenza B‐confirmed cases were genotyped by Haemagglutinin gene sequencing. We analyzed the clinical‐epidemiological characteristics of influenza B Lineages (Victoria/Yamagata) and WHO Groups.

Results

In the pre‐A/H1N1pdm09 period, influenza B‐associated ARI hospitalization incidence among children under five was low, ranging between 14.7 and 80.7 per 100 000 population. The incidence increased to between 51.4 and 330 in the post‐A/H1N1pdm09. Influenza B ARI cases were slightly older with milder symptoms. Both Victoria and Yamagata lineages were detected before the A/H1N1pdm09 outbreak; however, Victoria lineage became predominant in 2010‐2013 (84% Victoria vs 16% Yamagata). Victoria and Yamagata lineages did not differ in demographic and clinical characteristics. In Victoria lineage, Group1 ARI cases were clinically more severe compared to Group5, presenting a greater proportion of wheeze, tachypnea, and lower respiratory tract infection.

Conclusions

The current results highlight the increased incidence of influenza B‐related ARI hospitalization among children in central Vietnam in the post‐A/H1N1pdm09 era. Furthermore, the difference in clinical severity between Victoria lineage Group1 and 5 implies the importance of influenza B genetic variation on clinical presentation.

MONOCLONAL ANTIBODIES TO HEMAGGLUTININ OF INFLUENZA B VIRUSES VICTORIA EVOLUTIONARY LINEAGE

Co-circulation of two evolutionary distinct lineages of influenza virus in one epidemic season has led to development specific reagents for rapid identification and typing of new isolates. Panel of MAbs to hemagglutinin of influenza virus B/Brisbane/46/15 belonging to Victoria evolutionary lineage was developed. All MAbs reacted in ELISA with B/Victoria-like strains only. There were no interactions with heterologous influenza viruses of B/Yamagata lineage, seasonal and potentially pandemic influenza A viruses. All MAbs reacted in hemagglutination inhibition and virus neutralization. MAbs interacted in hemagglutination inhibition only with B/Victoria-like viruses, but did not interacted B/Yamagata-like strains. Neutralization and hemagglutination inhibition studies of viruses isolated before 1983 with MAbs revealed that MAbs 6E11, 9G5, 9B5 and 6A4 had the ability to interact with the virus B/ Russia/69 which may evidence that B strains of early isolation period (before lineage separation) have common epitope with recent Victoria lineage viruses. MAbs 7C8, 7G9, 7H8 and 8D11 were directed to a conserved epitope (or epitopes) specific for influenza hemagglutinin viruses of B/Victoria group. The presence of differences in the effectiveness of the interaction of MAbs 6A9, 7G9 and 8A8 in hemagglutination inhibition test allows the identification and differentiation of strains isolated in chicken embryos and MDCK cell culture. Thus, the developed MAbs can be successfully used for identification and antigenic analysis of B/Victoria-like strains.

The burden of influenza A and B in Mexico from the year 2010 to 2013: An observational, retrospective, database study, on records from the Directorate General of Epidemiology database

Despite vaccination programs, influenza still represents a significant disease burden in Mexico. We conducted an observational, retrospective analysis to better understand the epidemiological situation of the influenza virus in Mexico. Analysis of the seasonal patterns of influenza A and B were based on the Directorate General of Epidemiology dataset of influenza-like illness(ILI), and severe acute respiratory infection(SARI) that were recorded between January 2010 and December 2013. Our objectives were 1) to describe influenza A and B activity, by age group, and subtype and, 2) to analyze the number of laboratory-confirmed cases presenting with ILI by influenza type, the regional distribution of influenza, and its clinical features. Three periods of influenza activity were captured: August 2010-January 2011, December 2011-March 2012, and October 2012-March 2013. Cases were reported throughout Mexico, with 50.3% (n = 10,320) of cases found in 18-49 year olds. Over the entire capture period, a total of 76,085 ILI/SARI episodes had swab samples analyzed for influenza, 27% were positive. During the same period, influenza A cases were higher in the 18-49 years old, and influenza B cases in both 5-17 and 18-49 age groups. Peak activity occurred in January 2012 (n = 4,159) and December 2012 (n = 348) for influenza A and B respectively. This analysis confirms that influenza is an important respiratory pathogen for children and adults in Mexico despite vaccination recommendations. School-age children and adolescents were more prone to influenza B infection; while younger adults were susceptible to both influenza A and B viruses. Over the seasons, influenza A and B co-circulated.

Cost-utility of quadrivalent versus trivalent influenza vaccine in Brazil - comparison of outcomes from different static model types

Background

Influenza burden in Brazil is considerable with 4.2–6.4 million cases in 2008 and influenza-like-illness responsible for 16.9% of hospitalizations. Cost-effectiveness of influenza vaccination may be assessed by different types of models, with limitations due to data availability, assumptions, and modelling approach.

Objective

To understand the impact of model complexity, the cost-utility of quadrivalent versus trivalent influenza vaccines in Brazil was estimated using three distinct models: a 1-year decision tree population model with three age groups (FLOU); a more detailed 1-year population model with five age groups (FLORA); and a more complex lifetime multi-cohort Markov model with nine age groups (FLORENCE).

Methods

Analysis 1 (impact of model structure) compared each model using the same data inputs (i.e., best available data for FLOU). Analysis 2 (impact of increasing granularity) compared each model populated with the best available data for that model.

Results

Using the best data for each model, the discounted cost-utility ratio of quadrivalent versus trivalent influenza vaccine was R$20,428 with FLOU, R$22,768 with FLORA (versus R$20,428 in Analysis 1), and, R$19,257 with FLORENCE (versus R$22,490 in Analysis 1) using a lifetime horizon. Conceptual differences between FLORA and FLORENCE meant the same assumption regarding increased all-cause mortality in at-risk individuals had an opposite effect on the incremental cost-effectiveness ratio in Analysis 2 versus 1, and a proportionally higher number of vaccinated elderly in FLORENCE reduced this ratio in Analysis 2.

Discussion

FLOU provided adequate cost-effectiveness estimates with data in broad age groups. FLORA increased insights (e.g., in healthy versus at-risk, paediatric, respiratory/non-respiratory complications). FLORENCE provided greater insights and precision (e.g., in elderly, costs and complications, lifetime cost-effectiveness).

Conclusion

All three models predicted a cost per quality-adjusted life year gained for quadrivalent versus trivalent influenza vaccine in the range of R$19,257 (FLORENCE) to R$22,768 (FLORA) with the best available data in Brazil (Appendix A).

Molecular epidemiology of influenza B virus and implications in immunization strategy, Southern Brazil

Epidemiological indicators have shown the substantial impact of influenza B (Flu B) on the development of severe acute respiratory infection (SARI) and on mortality rates. In Brazil, the trivalent vaccine, composed of only one Flu B lineage is available. We investigated Flu B infections in clinical samples collected by the epidemiological surveillance service of Paraná State, Brazil, from 2013 to 2016. The Flu B lineages Yamagata- (B/Yam) and Victoria-like (B/Vic) were identified using the qRT-PCR assay, and notification forms were reviewed. Among 379 Flu B positive samples evaluated, 370 (98%) were characterized as B/Yam or B/Vic lineages. Both co-circulated with a frequency of 47% and 53%, respectively. B/Yam infected equally both genders, while B/Vic was more frequent in females (71%). The median age of patients infected by B/Vic (23y; 11-35) was lower than that of patients infected by B/Yam (32y; 12-50). Mismatch between the vaccine and the circulating strain was observed in the 2013 season, with a high number of SARI cases. B/Vic lineage was associated with a larger number of SARI cases (62%), while B/Yam with influenza-like illness (ILI) (61%). Differences were observed in the strains circulating in separate regions of Paraná State. B/Vic was prevalent in the northwestern (67%) and B/Yam in the southeastern region (60%). The unpredictability of Flu B lineage circulation causes a substantial increase in severe disease during epidemics in a vaccine mismatch season. In addition, the differences in the epidemiological profile of the target population of Flu B infections in relation to other respiratory viruses, as well as among the B/Vic and B/Yam lineages may also be associated to an increase in disease burden. These findings have direct consequences on vaccination strategies. Therefore, further molecular epidemiology studies of Flu B in Brazil are required to corroborate these primary results.

The Molecular Epidemiology and Evolutionary Dynamics of Influenza B Virus in Two Italian Regions during 2010-2015: The Experience of Sicily and Liguria

Molecular epidemiology of influenza B virus remained poorly studied in Italy, despite representing a major contributor to seasonal epidemics. This study aimed to reconstruct the phylogenetic relationships and genetic diversity of the hemagglutinin gene sequences of 197 influenza B strains circulating in both Southern (Sicily) and Northern (Liguria) Italy between 2010 and 2015. Upper respiratory tract specimens of patients displaying symptoms of influenza-like illness were screened by real-time RT-PCR assay for the presence of influenza B virus. PCR-positive influenza B samples were further analyzed by sequencing. Neighbor-joining phylogenetic trees were constructed and the amino-acid alignments were analyzed. Phylogenetic analysis showed clusters in B/Victoria clade 1A/1B (n = 29, 14.7%), and B/Yamagata clades 2 (n = 112, 56.8%) and 3 (n = 56, 28.4%). Both influenza B lineages were found to co-circulate during the study period, although a lineage swap from B/Victoria to B/Yamagata occurred in Italy between January 2011 and January 2013. The most represented amino-acid substitutions were N116K in the 120-loop (83.9% of B/Yamagata clade 3 strains) and I146V in the 150-loop (89.6% of B/Victoria clade 1 strains). D197N in 190-helix was found in almost all viruses collected. Our findings provide further evidence to support the adoption of quadrivalent influenza vaccines in our country.

Patterns of influenza B circulation in Brazil and its relevance to seasonal vaccine composition

Data on the burden of disease and circulation patterns of influenza B lineages for Brazil are limited. This review aims to describe the pattern of influenza B occurrence in Brazil to have a better understanding of its epidemiology and its relevance when considering seasonal influenza vaccine composition.

A review of the data including analysis of international and local surveillance data as well as information from online search of databases using Medical Subject Headings terms in conjunction with screening of abstracts from scientific events was performed.

Based on international epidemiologic surveillance data, moderate levels of influenza B disease (19%; 2006–2014) were observed. Of these nine years, it was possible to compare data from three years (2007, 2008 and 2013) which have information on the circulating influenza B lineage. Co-circulation of influenza B lineages was observed in all these three influenza seasons, of which, during one season, a high degree of mismatch between the vaccine lineage and the predominant circulating lineage (91.4% [2013]) was observed. Local surveillance data reveal a distinct and dynamic distribution of respiratory viruses over the years. Data from published literature and abstracts show that influenza B is a significant cause of disease with an unpredictable circulation pattern and showing trends indicating reemergence of the B/Victoria lineage. The abstracts report notable levels of co-circulation of both influenza B lineages (2000–2013). Mismatch between the Southern hemisphere vaccine and the most prevalent circulating viruses in Brazil were observed in five influenza seasons.

The evidence on co-circulation of two influenza B lineages and mismatched seasons in Brazil indicates the benefit of quadrivalent influenza vaccines in conferring broader seasonal influenza protection. Additionally, improving influenza surveillance platforms in Brazil is important for monitoring disease trends and the impact of introducing seasonal influenza vaccination.

Detection of influenza B lineages from 2001 to 2013 in a tertiary hospital in the city of São Paulo, Brazil

Two antigenically distinct lineages of influenza B viruses, the Victoria-like and Yamagata-like strains, currently circulate among humans. Surveillance from United States of America and Europe over the last 10 years showed that the chance of a correct matching between vaccine and the circulating lineage had been 50%. We investigated influenza B infection in different patient groups (asymptomatic, general community, with comorbidities and hospitalised) attended at a tertiary hospital in the city of São Paulo, Brazil between 2001-2013. All samples were screened for influenza B virus by one-step real-time reverse transcription-polymerase chain reaction. From 2,992 respiratory samples collected, 114 (3.8%) tested positive for influenza B. Teenagers (13-18 years) presented the highest rate of 18.5% (odds ratio 22.87, 95% confidence interval 2.90-180.66, p < 0.001). One hundred nine samples could be characterised: 50 were Yamagata-like and 59 were Victoria-like strains. Mismatching between the vaccine and predominant circulating strain was observed in 2002 and 2013 seasons. Based on data collected during a period of 12 years, we found that influenza B was more frequent in teenagers. Co-circulation of both lineages and mismatch with the vaccine strain can occur. Our data highlighted the importance of quadrivalent vaccines and future analysis of the age groups included in vaccination programs.

Influenza B virus-specific CD8+ T-lymphocytes strongly cross-react with viruses of the opposing influenza B lineage

Influenza B viruses fall in two antigenically distinct lineages (B/Victoria/2/1987 and B/Yamagata/16/1988 lineage) that co-circulate with influenza A viruses of the H3N2 and H1N1 subtypes during seasonal epidemics. Infections with influenza B viruses contribute considerably to morbidity and mortality in the human population. Influenza B virus neutralizing antibodies, elicited by natural infections or vaccination, poorly cross-react with viruses of the opposing influenza B lineage. Therefore, there is an increased interest in identifying other correlates of protection which could aid the development of broadly protective vaccines. blast analysis revealed high sequence identity of all viral proteins. With two online epitope prediction algorithms, putative conserved epitopes relevant for study subjects used in the present study were predicted. The cross-reactivity of influenza B virus-specific polyclonal CD8+ cytotoxic T-lymphocyte (CTL) populations obtained from HLA-typed healthy study subjects, with intra-lineage drift variants and viruses of the opposing lineage, was determined by assessing their in vitro IFN-γ response and lytic activity. Here, we show for the first time, to the best of our knowledge, that CTLs directed to viruses of the B/Victoria/2/1987 lineage cross-react with viruses of the B/Yamagata/16/1988 lineage and vice versa.

Inactivated Viral Vaccines

Inactivated vaccines have been used for over a century to induce protection against viral pathogens. This established approach of vaccine production is relatively straightforward to achieve and there is an augmented safety profile as compared to their live counterparts. Today, there are six viral pathogens for which licensed inactivated vaccines are available with many more in development. Here, we describe the principles of viral inactivation and the application of these principles to vaccine development. Specifically emphasized are the manufacturing procedure and the accompanying assays, of which assays used for monitoring the inactivation process and preservation of neutralizing epitopes, are pivotal. Novel inactivated vaccines in development and the hurdles they face for licensure are also discussed as well as the (dis)advantages of inactivation over the other vaccine production methodologies.

Molecular characterization of influenza B virus outbreak on a cruise ship in Brazil 2012

In February 2012, an outbreak of respiratory illness occurred on the cruise ship MSC Armonia in Brazil. A 31-year-old female crew member was hospitalized with respiratory failure and subsequently died. To study the etiology of the respiratory illness, tissue taken at necropsy from the deceased woman and respiratory specimens from thirteen passengers and crew members with respiratory symptoms were analyzed. Influenza real-time RT-PCR assays were performed, and the full-length hemagglutinin (HA) gene of influenza-positive samples was sequenced. Influenza B virus was detected in samples from seven of the individuals, suggesting that it was the cause of this respiratory illness outbreak. The sequence analysis of the HA gene indicated that the virus was closely related to the B/Brisbane/60/2008-like virus, Victoria lineage, a virus contained in the 2011-12 influenza vaccine for the Southern Hemisphere. Since the recommended composition of the influenza vaccine for use during the 2013 season changed, an intensive surveillance of viruses circulating worldwide is crucial. Molecular analysis is an important tool to characterize the pathogen responsible for an outbreak such as this. In addition, laboratory disease surveillance contributes to the control measures for vaccine-preventable influenza.