Occurrence of influenza B/Hong Kong-like strains in Brazil, during 2002

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.

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

Since the 1980s, 2 antigenically distinct influenza B lineages have cocirculated in the world: B/Victoria/2/87 (first appeared in the 1980s) and B/Yamagata/16/88 (became predominant in the 1990s). B/Victoria/2/87 isolates were geographically restricted to eastern Asia during 1991-2000. During 2000-2001 and 2001-2002, B/Victoria/2/87 isolates reemerged in North America, Europe, and South America, and then spread globally. During influenza virus surveillance, season 2002, an outbreak of acute respiratory illness, which quickly spread among the population, has been notified by public health authorities living in Araraquara, São Paulo, Brazil. Instituto Adolfo Lutz and Secretariat of Health of São Paulo state teams initiate an investigation towards to describe the pattern of infection in this population temporally and by age and to characterize the strains by virus isolation and hemagglutination inhibition assay. The outbreak lasted approximately 10 weeks; many cases occurred between mid-August and mid-September. Children younger than 13 years were the most affected; the elderly were mostly immune to infection. Analysis of the clinical respiratory samples helped in identifying the B/Hong Kong/330/2001 and B/Brisbane/32/2002 subtypes-recent variants of B/Victoria/02/88, a lineage restricted to Southeast Asia until 2001. The Araraquara outbreak confirms the reemergence of the B/Victoria viruses in South America and highlights the importance of monitoring local circulating strains, especially in light of the absence of cross-protection between antigenically distinct influenza lineages. Based on influenza virus surveillance, public health authorities worldwide should decide whether trivalent vaccines or quadrivalent vaccines (containing both influenza virus B lineages) are to be used in each country.

Burden of influenza in Latin America and the Caribbean: a systematic review and meta-analysis

OBJECTIVE

Influenza causes severe morbidity and mortality. This systematic review aimed to assess the incidence, etiology, and resource usage for influenza in Latin America and the Caribbean.

DESIGN

Meta-analytic systematic review. Arcsine transformations and DerSimonian Laird random effects model were used for meta-analyses.

SETTING

A literature search from 1980 to 2008 in MEDLINE, Cochrane Library, EMBASE, LILACS, Ministries of Health, PAHO, proceedings, reference lists, and consulting experts.

SAMPLE

We identified 1092 references, of which 31 were finally included, in addition to influenza surveillance reports. We also used information from the 10 reports from the collaborative group for epidemiological surveillance of influenza and other respiratory virus (GROG), and information retrieved from the WHO global flu database FLUNET.

MAIN OUTCOME MEASURES

Incidence, percentage of influenza specimens out of the total received by influenza centers and resource-use outcomes.

RESULTS

A total of 483 130 specimens of patients with influenza were analyzed. Meta-analysis showed an annual rate of 36 080 (95%CI 28 550 43 610) influenza-like illness per 100 000 persons-years. The percentage of influenza out of total specimens received by influenza centers ranged between 4.66% and 15.42%, with type A the most prevalent, and A subtype H3 predominating. The mean length of stay at hospital due to influenza ranged between 5.8 12.9 days, total workdays lost due to influenza-like illnesses were 17 150 days, and the mean direct cost of hospitalization was US$575 per laboratory-confirmed influenza case.

CONCLUSIONS

Our data show that seasonal influenza imposes a high morbidity and economic burden to the region. However, the vaccine-uptake rate has been low in this region. Population-based cohort studies are required to improve the knowledge about incidence and resource utilization, which would inform healthcare authorities for decision making.

The epidemiology and antigenic characterization of influenza viruses isolated in Curitiba, South Brazil

Several studies conducted all over the world have reported that the influenza virus is associated with great morbidity and mortality rates. In this study, we analyzed the incidence of the influenza virus between 2000 and 2003 in Curitiba. We studied 1621 samples obtained from outpatients and hospitalized patients of both sexes and all ages. The study was conducted at the local primary care health units (outpatients) and at the tertiary care unit (hospitalized) of the General Hospital of the Federal University in the state of Paraná, Brazil. Nasopharyngeal aspirates and, eventually, bronchoalveolar lavage were assayed for the presence of viral antigens, either by indirect immunofluorescence or cell culture. Of the samples studied, 135 (8.3%) were positive for influenza virus, and of those, 103 (76.3%) were positive for type A and 32 (23.7%) for type B. Additionally, positive samples were analyzed by reverse transcription followed by polymerase chain reaction and subtypes H1 and H3 were identified from this group. A high incidence of positive samples was observed mainly in the months with lower temperatures. Furthermore, outpatients showed a higher incidence of influenza viruses than hospitalized patients.

Influenza vaccination in Brazil: rationale and caveats

Mass vaccination campaigns against influenza in the elderly have been conducted in Brazil since 1999. A search of the literature on influenza in Brazil indicated that data on disease burden are still scarce and inaccurate. Published data seem to indicate that vaccination has produced some impact in the southern and southeastern regions but not in other regions of Brazil. A discussion of the technical and scientific rationale for mass immunization against influenza is presented and it is argued that the current strategy has not taken into account potential differences in disease occurrence in different areas. It is suggested some epidemiological surveillance actions needed to address major concerns regarding mass influenza vaccination and its impact in Brazil.