Genomic diversity and evolutionary dynamics of Influenza A viruses in Colombian swine: implications for one health surveillance and control.

Influenza A viruses (IAV) impose significant respiratory disease burdens in both swine and humans worldwide, with frequent human-to-swine transmission driving viral evolution in pigs and highlighting the risk at the animal-human interface. Therefore, a comprehensive One Health approach (interconnection among human, animal, and environmental health) is needed for IAV prevention, control, and response. Animal influenza genomic surveillance remains limited in many Latin American countries, including Colombia. To address this gap, we genetically characterized 170 swine specimens from Colombia (2011-2017). Whole genome sequencing revealed a predominance of pandemic-like H1N1 lineage, with a minority belonging to H3N2 and H1N2 human seasonal-like lineage and H1N1 early classical swine lineages. Significantly, we have identified reassortant and recombinant viruses (H3N2, H1N1) not previously reported in Colombia. This suggests a broad genotypic viral diversity, likely resulting from reassortment between classical endemic viruses and new introductions established in Colombia's swine population (e.g. the 2009 H1N1 pandemic). Our study highlights the importance of a One Health approach in disease control, particularly in an ecosystem where humans are a main source of IAV to swine populations, and emphasizes the need for continued surveillance and enhanced biosecurity measures. The co-circulation of multiple subtypes in regions with high swine density facilitates viral exchange, underscoring the importance of monitoring viral evolution to inform vaccine selection and public health policies locally and globally.

Low antiviral resistance in Influenza A and B viruses isolated in Mexico from 2010 to 2023.

The most widely used class of antivirals available for Influenza treatment are the neuraminidase inhibitors (NAI) Oseltamivir and Zanamivir. However, amino acid (AA) substitutions in the neuraminidase may cause reduced inhibition or high antiviral resistance. In Mexico, the current state of knowledge about NAI susceptibility is scarce, in this study we report the results of 14 years of Influenza surveillance by phenotypic and genotypic methods. A total of 255 isolates were assessed with the NAI assay, including Influenza A(H1N1)pdm09, A(H3N2) and Influenza B (IBV). Furthermore, 827 sequences contained in the GISAID platform were analyzed in search of relevant mutations.Overall, five isolates showed highly reduced inhibition or reduced inhibition to Oseltamivir, and two showed reduced inhibition to Zanamivir in the NAI assays. Additionally, five A(H1N1)pdm09 sequences from the GISAID possessed AA substitutions associated to reduced inhibition to Oseltamivir and none to Zanamivir. Oseltamivir resistant A(H1N1)pdm09 harbored the H275Y mutation. No genetic mutations were identified in Influenza A(H3N2) and IBV. Overall, these results show that in Mexico the rate of NAI resistance is low (0.6%), but it is essential to continue the Influenza surveillance in order to understand the drug susceptibility of circulating strains.

Detection and Characterization of Influenza A Virus Endemic Circulation in Suckling and Nursery Pigs Originating from Vaccinated Farms in the Same Production System.

Inactivated influenza A virus (IAV) vaccines help reduce clinical disease in suckling piglets, although endemic infections still exist. The objective of this study was to evaluate the detection of IAV in suckling and nursery piglets from IAV-vaccinated sows from farms with endemic IAV infections. Eight nasal swab collections were obtained from 135 two-week-old suckling piglets from four farms every other week from March to September 2013. Oral fluid samples were collected from the same group of nursery piglets. IAV RNA was detected in 1.64% and 31.01% of individual nasal swabs and oral fluids, respectively. H1N2 was detected most often, with sporadic detection of H1N1 and H3N2. Whole-genome sequences of IAV isolated from suckling piglets revealed an H1 hemagglutinin (HA) from the 1B.2.2.2 clade and N2 neuraminidase (NA) from the 2002A clade. The internal gene constellation of the endemic H1N2 was TTTTPT with a pandemic lineage matrix. The HA gene had 97.59% and 97.52% nucleotide and amino acid identities, respectively, to the H1 1B.2.2.2 used in the farm-specific vaccine. A similar H1 1B.2.2.2 was detected in the downstream nursery. These data demonstrate the low frequency of IAV detection in suckling piglets and downstream nurseries from farms with endemic infections in spite of using farm-specific IAV vaccines in sows.

Novel influenza A viruses in pigs with zoonotic potential, Chile.

Novel H1N2 and H3N2 swine influenza A viruses (IAVs) have recently been identified in Chile. The objective of this study was to evaluate their zoonotic potential. We perform phylogenetic analyses to determine the genetic origin and evolution of these viruses, and a serological analysis to determine the level of cross-protective antibodies in the human population. Eight genotypes were identified, all with pandemic H1N1 2009-like internal genes. H1N1 and H1N2 were the subtypes more commonly detected. Swine H1N2 and H3N2 IAVs had hemagglutinin and neuraminidase lineages genetically divergent from IAVs reported worldwide, including human vaccine strains. These genes originated from human seasonal viruses were introduced into the swine population since the mid-1980s. Serological data indicate that the general population is susceptible to the H3N2 virus and that elderly and young children also lack protective antibodies against the H1N2 strains, suggesting that these viruses could be potential zoonotic threats. Continuous IAV surveillance and monitoring of the swine and human populations is strongly recommended.IMPORTANCEIn the global context, where swine serve as crucial intermediate hosts for influenza A viruses (IAVs), this study addresses the pressing concern of the zoonotic potential of novel reassortant strains. Conducted on a large scale in Chile, it presents a comprehensive account of swine influenza A virus diversity, covering 93.8% of the country's industrialized swine farms. The findings reveal eight distinct swine IAV genotypes, all carrying a complete internal gene cassette of pandemic H1N1 2009 origin, emphasizing potential increased replication and transmission fitness. Genetic divergence of H1N2 and H3N2 IAVs from globally reported strains raises alarms, with evidence suggesting introductions from human seasonal viruses since the mid-1980s. A detailed serological analysis underscores the zoonotic threat, indicating susceptibility in the general population to swine H3N2 and a lack of protective antibodies in vulnerable demographics. These data highlight the importance of continuous surveillance, providing crucial insights for global health organizations.

Influenza A virus antibodies in dogs, hunting dogs, and backyard pigs in Campeche, Mexico.

AIMS: This study aimed to identify exposure to human, swine, and avian influenza A virus subtypes in rural companion and hunting dogs, backyard pigs, and feral pigs. METHODS AND RESULTS: The study took place in a region of southeastern Mexico where the sampled individuals were part of backyard production systems in which different domestic and wild species coexist and interact with humans. We collected blood samples from pigs and dogs at each of the sites. We used a nucleoprotein enzyme-linked immunosorbent assay to determine the exposure of individuals to influenza A virus. Haemagglutination inhibition was performed on the positive samples to determine the subtypes to which they were exposed. For data analysis, a binomial logistic regression model was generated to determine the predictor variables for the seropositivity of the individuals in the study. We identified 11 positive individuals: three backyard pigs, four companion dogs, and four hunting dogs. The pigs tested positive for H1N1 and H1N2. The dogs were positive for H1N1, H1N2, and H3N2. The model showed that dogs in contact with backyard chickens are more likely to be seropositive for influenza A viruses. CONCLUSIONS: We demonstrated the essential role hunting dogs could play as intermediate hosts and potential mixing vessel hosts when exposed to human and swine-origin viral subtypes. These results are relevant because these dogs interact with domestic hosts and humans in backyard systems, which are risk scenarios in the transmission of influenza A viruses. Therefore, it is of utmost importance to implement epidemiological surveillance of influenza A viruses in backyard animals, particularly in key animals in the transmission of these viruses, such as dogs and pigs.

Safety and immunogenicity of influenza A(H3N2) component vaccine in juvenile systemic lupus erythematosus.

INTRODUCTION: Seasonal influenza A (H3N2) virus is an important cause of morbidity and mortality in the last 50 years in population that is greater than the impact of H1N1. Data assessing immunogenicity and safety of this virus component in juvenile systemic lupus erythematosus (JSLE) is lacking in the literature. OBJECTIVE: To evaluate short-term immunogenicity and safety of influenza A/Singapore (H3N2) vaccine in JSLE. METHODS: 24 consecutive JSLE patients and 29 healthy controls (HC) were vaccinated with influenza A/Singapore/INFIMH-16-0019/2016(H3N2)-like virus. Influenza A (H3N2) seroprotection (SP), seroconversion (SC), geometric mean titers (GMT), factor increase in GMT (FI-GMT) titers were assessed before and 4 weeks post-vaccination. Disease activity, therapies and adverse events (AE) were also evaluated. RESULTS: JSLE patients and controls were comparable in current age [14.5 (10.1-18.3) vs. 14 (9-18.4) years, p = 0.448] and female sex [21 (87.5%) vs. 19 (65.5%), p = 0.108]. Before vaccination, JSLE and HC had comparable SP rates [22 (91.7%) vs. 25 (86.2%), p = 0.678] and GMT titers [102.3 (95% CI 75.0-139.4) vs. 109.6 (95% CI 68.2-176.2), p = 0.231]. At D30, JSLE and HC had similar immune response, since no differences were observed in SP [24 (100%) vs. 28 (96.6%), p = 1.000)], SC [4 (16.7%) vs. 9 (31.0%), p = 0.338), GMT [162.3 (132.9-198.3) vs. 208.1 (150.5-287.8), p = 0.143] and factor increase in GMT [1.6 (1.2-2.1) vs. 1.9 (1.4-2.5), p = 0.574]. SLEDAI-2K scores [2 (0-17) vs. 2 (0-17), p = 0.765] and therapies remained stable throughout the study. Further analysis of possible factors influencing vaccine immune response among JSLE patients demonstrated similar GMT between patients with SLEDAI < 4 compared to SLEDAI ≥ 4 (p = 0.713), as well as between patients with and without current use of prednisone (p = 0.420), azathioprine (p = 1.0), mycophenolate mofetil (p = 0.185), and methotrexate (p = 0.095). No serious AE were reported in both groups and most of them were asymptomatic (58.3% vs. 44.8%, p = 0.958). Local and systemic AE were alike in both groups (p > 0.05). CONCLUSION: This is the first study that identified adequate immune protection against H3N2-influenza strain with additional vaccine-induced increment of immune response and an adequate safety profile in JSLE. ( www. CLINICALTRIALS: gov , NCT03540823).

Immunological profile of mice immunized with a polyvalent virosome-based influenza vaccine.

BACKGROUND: Influenza A virus (IAV) causes respiratory disease in pigs and is a major concern for public health. Vaccination of pigs is the most successful measure to mitigate the impact of the disease in the herds. Influenza-based virosome is an effective immunomodulating carrier that replicates the natural antigen presentation pathway and has tolerability profile due to their purity and biocompatibility. METHODS: This study aimed to develop a polyvalent virosome influenza vaccine containing the hemagglutinin and neuraminidase proteins derived from the swine IAVs (swIAVs) H1N1, H1N2 and H3N2 subtypes, and to investigate its effectiveness in mice as a potential vaccine for swine. Mice were immunized with two vaccine doses (1 and 15 days), intramuscularly and intranasally. At 21 days and eight months later after the second vaccine dose, mice were euthanized. The humoral and cellular immune responses in mice vaccinated intranasally or intramuscularly with a polyvalent influenza virosomal vaccine were investigated. RESULTS: Only intramuscular vaccination induced high hemagglutination inhibition (HI) titers. Seroconversion and seroprotection (> 4-fold rise in HI antibody titers, reaching a titer of ≥ 1:40) were achieved in 80% of mice (intramuscularly vaccinated group) at 21 days after booster immunization. Virus-neutralizing antibody titers against IAV were detected at 8 months after vaccination, indicating long-lasting immunity. Overall, mice immunized with the virosome displayed greater ability for B, effector-T and memory-T cells from the spleen to respond to H1N1, H1N2 and H3N2 antigens. CONCLUSIONS: All findings showed an efficient immune response against IAVs in mice vaccinated with a polyvalent virosome-based influenza vaccine.

A polyvalent virosomal influenza vaccine induces broad cellular and humoral immunity in pigs.

BACKGROUND: Influenza A virus (IAV) is endemic in pigs globally and co-circulation of genetically and antigenically diverse virus lineages of subtypes H1N1, H1N2 and H3N2 is a challenge for the development of effective vaccines. Virosomes are virus-like particles that mimic virus infection and have proven to be a successful vaccine platform against several animal and human viruses. METHODS: This study evaluated the immunogenicity of a virosome-based influenza vaccine containing the surface glycoproteins of H1N1 pandemic, H1N2 and H3N2 in pigs. RESULTS: A robust humoral and cellular immune response was induced against the three IAV subtypes in pigs after two vaccine doses. The influenza virosome vaccine elicited hemagglutinin-specific antibodies and virus-neutralizing activity. Furthermore, it induced a significant maturation of macrophages, and proliferation of B lymphocytes, effector and central memory CD4+ and CD8+ T cells, and CD8+ T lymphocytes producing interferon-γ. Also, the vaccine demonstrated potential to confer long-lasting immunity until the market age of pigs and proved to be safe and non-cytotoxic to pigs. CONCLUSIONS: This virosome platform allows flexibility to adjust the vaccine content to reflect the diversity of circulating IAVs in swine in Brazil. The vaccination of pigs may reduce the impact of the disease on swine production and the risk of swine-to-human transmission.

Robust immunogenicity to the H3N2 component of influenza A vaccine in primary Sjögren syndrome.

INTRODUCTION: Influenza A (H3N2) virus is the major cause of morbidity/mortality due to seasonal influenza over 50 years. Data about the safety/immunogenicity of influenza A/Singapore (H3N2) vaccine are scarce in primary Sjögren syndrome (pSS). METHODS: Twenty-one consecutive pSS patients and 42 HC (healthy control individuals) were immunized with influenza A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus. Rates of SP (seroprotection) and SC (seroconversion), GMT (geometric mean titers), FI-GMT (factor increase in GMT), ESSDAI (EULAR Sjögren's Syndrome Disease Activity Index), and adverse events were appraised before and 4 weeks post-vaccination. RESULTS: pSS and HC had similar mean age (51.2 ± 14.2 vs. 50.6 ± 12.1 years, p = 0.886). Pre-vaccination SP rates were high in pSS and HC (90.5% vs. 71.4%, p = 0.114), and GMT were higher in pSS [80.0 (52.4-160.0) vs. 40.0 (20.0-80.0), p = 0.001]. The percentage of influenza vaccination in the preceding two years was elevated and similar in pSS and HC (94.1% vs. 94.6%, p = 1.000). GMT values augmented in both groups four weeks after vaccination and persisted higher in the first group [160.0 (80.0-320.0) vs. 80.0 (40.0-80.0), p < 0.001] with equivalent FI-GMT [1.4 (1.0-2.8) vs. 1.4 (1.0-2.0), p = 0.410]. Both groups had low and similar SC rates (19.0% vs. 9.5%, p = 0.423). ESSDAI values persisted steadily during the study (p = 0.313). No serious adverse events have occurred. CONCLUSION: The novel demonstration that the influenza A/Singapore (H3N2) vaccine induces a different pattern of immunogenicity from other influenza A constituents in pSS, featured by a desirable high pre- and post-vaccination immunogenicity, is in line with reported differences in immune responses between strains in trivalent vaccines and may be related to pre-existing immunity. CLINICALTRIALS: gov: #NCT03540823. Key Points • This prospective study demonstrated a robust pre- and post-vaccination immunogenicity to influenza A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus in primary Sjögren's syndrome (pSS). • This high immunogenicity pattern may be related to pre-existing immunization, or else it is related to immunogenicity differences of each strain. • This vaccine had an adequate safety profile in pSS, with no impact on disease activity.

End-of-season influenza vaccine effectiveness during the Southern Hemisphere 2022 influenza season - Chile, Paraguay, and Uruguay.

OBJECTIVES: This study estimated the 2022 end-of-season influenza vaccine effectiveness (VE) against severe acute respiratory illness (SARI) hospitalization in Chile, Paraguay, and Uruguay. METHODS: We pooled surveillance data from SARI cases in 18 sentinel surveillance hospitals in Chile (n = 9), Paraguay (n = 2), and Uruguay (n = 7) from March 16-November 30, 2022. VE was estimated using a test-negative design and logistic regression models adjusted for country, age, sex, presence of ≥1 comorbidity, and week of illness onset. VE estimates were stratified by influenza virus type and subtype (when available) and influenza vaccine target population, categorized as children, individuals with comorbidities, and older adults, defined per countries' national immunization policies. RESULTS: Among the 3147 SARI cases, there were 382 (12.1%) influenza test-positive case patients; 328 (85.9%) influenza case patients were in Chile, 33 (8.6%) were in Paraguay, and 21 (5.5%) were in Uruguay. In all countries, the predominant subtype was influenza A(H3N2) (92.6% of influenza cases). Adjusted VE against any influenza-associated SARI hospitalization was 33.8% (95% confidence interval: 15.3%, 48.2%); VE against influenza A(H3N2)-associated SARI hospitalization was 30.4% (95% confidence interval: 10.1%, 46.0%). VE estimates were similar across target populations. CONCLUSION: During the 2022 influenza season, influenza vaccination reduced the odds of hospitalization among those vaccinated by one-third. Health officials should encourage influenza vaccination in accordance with national recommendations.

Influenza A(H3N2) infection followed by separate COVID-19 infection

[ABSTRACT]. This study describes the case of a health professional infected first by influenza virus A(H3N2) and then by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 11 days later. Respiratory samples and clinical data were collected from the patient and from close contacts. RNA was extracted from samples and reverse transcription–quantitative polymerase chain reaction (RT-qPCR) was used to investigate the viruses. The patient presented with two different illness events: the first was characterized by fever, chest and body pain, prostration and tiredness, which ceased on the ninth day; RT-qPCR was positive only for influenza virus A(H3N2). Eleven days after onset of the first symptoms, the patient presented with sore throat, nasal con- gestion, coryza, nasal itching, sneezing and coughing, and a second RT-qPCR test was positive only for SARS-CoV-2; in the second event, symptoms lasted for 11 days. SARS-CoV-2 sequencing identified the Omi- cron BA.1 lineage. Of the patient’s contacts, one was coinfected with influenza A(H3N2) and SARS-CoV-2 lineage BA.1.15 and the other two were infected only with SARS-CoV-2, one also with Omicron BA.1.15 and the other with BA.1.1. Our findings reinforce the importance of testing for different viruses in cases of suspected respiratory viral infection during routine epidemiological surveillance because common clinical manifestations of COVID-19 mimic those of other viruses, such as influenza.

[RESUMEN]. Este estudio describe el caso de un profesional de la salud que contrajo la infección primero por el virus de la gripe A (H3N2) y a continuación por el coronavirus 2 del síndrome respiratorio agudo grave (SARS-CoV-2) 11 días después. Se recogieron muestras respiratorias y datos clínicos del paciente y sus contactos cercanos. Se extrajo ARN de muestras y se utilizó la reacción en cadena de la polimerasa cuantitativa con transcripción inversa (RT-qPCR, por su sigla en inglés) para investigar los virus. El paciente presentó dos procesos infecciosos distintos: el primero se caracterizó por fiebre, dolor corporal y torácico, postración y cansancio, que cesó en el noveno día. La prueba mediante RT-qPCR solo fue positiva en el virus de la gripe A (H3N2). Once días después del inicio de los primeros síntomas, el paciente manifestó dolor de garganta, congestión nasal, catarro, picazón nasal, estornudos y tos. Una segunda prueba mediante RT-qPCR solo fue positiva para el SARS-CoV-2 y durante este segundo proceso los síntomas duraron 11 días. La secuenciación del SARS-CoV-2 identificó el linaje ómicron BA.1. De los contactos del paciente, uno presentaba una coinfección por el virus de la gripe A (H3N2) y el linaje BA.1.15 del SARS-COV-2, y los otros dos presentaban infecciones únicamente por SARS-CoV-2, uno también del linaje ómicron BA.1.15 y el otro de BA.1.1. Estos hallazgos refuerzan la importancia de realizar pruebas para detectar diferentes virus en casos de sospecha de infección viral respiratoria durante la vigilancia epidemiológica de rutina porque las manifestaciones clínicas comunes de COVID-19 son similares a las de otros virus, como en el caso de la gripe.

[RESUMO]. Este estudo descreve o caso de uma profissional de saúde infectada primeiro pelo vírus influenza A (H3N2) e, 11 dias depois, pelo coronavírus da síndrome respiratória aguda grave 2 (SARS-CoV-2). Amostras respiratórias e dados clínicos foram coletados da paciente e de contatos próximos. RNA foi extraído das amostras, e o método de reação em cadeia da polimerase via transcriptase reversa quantitativa (RT-qPCR) foi utilizado para investigar os vírus. A paciente apresentou dois quadros clínicos distintos. O primeiro foi caracterizado por febre, dor no peito e no corpo, prostração e fadiga, que cessou no nono dia. A RT-qPCR foi positiva apenas para o vírus da influenza A (H3N2). Onze dias após o início dos primeiros sintomas, a paciente apresentou dor de garganta, congestão nasal, coriza, prurido nasal, espirros e tosse. Um segundo teste de RT-qPCR foi positivo apenas para SARS-CoV-2. No segundo evento, os sintomas duraram 11 dias. O sequenciamento do SARS-CoV-2 identificou a cepa Ômicron BA.1. Dentre os contatos da paciente, um teve coinfeção por influenza A (H3N2) e SARS-COV-2 (cepa BA.1.15), e os outros dois foram infectados apenas por SARS-CoV-2 (um também pela cepa Ômicron BA.1.15 e o outro pela BA.1.1). Nossos achados reforçam a importância de testes para a detecção de diferentes vírus em casos de suspeita de infecção viral respiratória durante a vigilância epidemiológica de rotina, visto que as manifestações clínicas comuns da COVID-19 imitam as de outros vírus, como o vírus influenza.

Introductions of Human-Origin Seasonal H3N2, H1N2 and Pre-2009 H1N1 Influenza Viruses to Swine in Brazil.

In South America, the evolutionary history of influenza A virus (IAV) in swine has been obscured by historically low levels of surveillance, and this has hampered the assessment of the zoonotic risk of emerging viruses. The extensive genetic diversity of IAV in swine observed globally has been attributed mainly to bidirectional transmission between humans and pigs. We conducted surveillance in swine in Brazil during 2011-2020 and characterized 107 H1N1, H1N2, and H3N2 IAVs. Phylogenetic analysis based on HA and NA segments revealed that human seasonal IAVs were introduced at least eight times into swine in Brazil since the mid-late 1980s. Our analyses revealed three genetic clades of H1 within the 1B lineage originated from three distinct spillover events, and an H3 lineage that has diversified into three genetic clades. The N2 segment from human seasonal H1N2 and H3N2 viruses was introduced into swine six times and a single introduction of an N1 segment from the human H1N1 virus was identified. Additional analysis revealed further reassortment with H1N1pdm09 viruses. All these introductions resulted in IAVs that apparently circulate only in Brazilian herds. These results reinforce the significant contributions of human IAVs to the genetic diversity of IAV in swine and reiterate the importance of surveillance of IAV in pigs.

Spatial, temporal and evolutionary insight into seasonal epidemic Influenza A virus strains near the equatorial line: The case of Ecuador.

To study the spatial and temporal patterns of Influenza A virus (IAV) is essential for an efficient control of the disease caused by IAV and efficient vaccination programs. However, spatiotemporal patterns of spread as well as genetic lineage circulation of IAV on a countrywide scale have not been clearly determined for many tropical regions of the world. In order to gain insight into these matters, the spatial and temporal patterns of IAV in six different geographic regions of Ecuador, from 2011 to 2021, were determined and the timing and magnitude of IAV outbreaks in these localities investigated. The results of these studies revealed that although Ecuador is a South American country situated in the Equator line, its IAV epidemiology resembles that of temperate Northern Hemisphere countries. Phylogenetic analysis of H1N1pdm09 and H3N2 IAV strains isolated in five different localities of Ecuador revealed that provinces in the south of this country have the largest effective population size by comparison with provinces in the north, suggesting that the southern provinces may be acting as a source of IAV. Co-circulation of different H1N1pdm09 and H3N2 genetic lineages was observed in different geographic regions of Ecuador.

Influenza Incidence and Vaccine Effectiveness During the Southern Hemisphere Influenza Season - Chile, 2022.

The COVID-19 pandemic has affected influenza virus transmission, with historically low activity, atypical timing, or altered duration of influenza seasons during 2020-22 (1,2). Community mitigation measures implemented since 2020, including physical distancing and face mask use, have, in part, been credited for low influenza detections globally during the pandemic, compared with those during prepandemic seasons (1). Reduced population exposure to natural influenza infections during 2020-21 and relaxed community mitigation measures after introduction of COVID-19 vaccines could increase the possibility of severe influenza epidemics. Partners in Chile and the United States assessed Southern Hemisphere influenza activity and estimated age-group-specific rates of influenza-attributable hospitalizations and vaccine effectiveness (VE) in Chile in 2022. Chile's most recent influenza season began in January 2022, which was earlier than during prepandemic seasons and was associated predominantly with influenza A(H3N2) virus, clade 3C.2a1b.2a.2. The cumulative incidence of influenza-attributable pneumonia and influenza (P&I) hospitalizations was 5.1 per 100,000 person-years during 2022, which was higher than that during 2020-21 but lower than incidence during the 2017-19 influenza seasons. Adjusted VE against influenza A(H3N2)-associated hospitalization was 49%. These findings indicate that influenza activity continues to be disrupted after emergence of SARS-CoV-2 in 2020. Northern Hemisphere countries might benefit from preparing for an atypical influenza season, which could include early influenza activity with potentially severe disease during the 2022-23 season, especially in the absence of prevention measures, including vaccination. Health authorities should encourage all eligible persons to seek influenza vaccination and take precautions to reduce transmission of influenza (e.g., avoiding close contact with persons who are ill).

Low prevalence of influenza A strains with resistance markers in Brazil during 2017-2019 seasons.

The influenza A virus (IAV) is of a major public health concern as it causes annual epidemics and has the potential to cause pandemics. At present, the neuraminidase inhibitors (NAIs) are the most widely used anti-influenza drugs, but, more recently, the drug baloxavir marboxil (BXM), a polymerase inhibitor, has also been licensed in some countries. Mutations in the viral genes that encode the antiviral targets can lead to treatment resistance. Worldwide, a low prevalence of antiviral resistant strains has been reported. Despite that, this situation can change rapidly, and resistant strain surveillance is a priority. Thus, the aim of this was to evaluate Brazilian IAVs antiviral resistance from 2017 to 2019 through the identification of viral mutations associated with reduced inhibition of the drugs and by testing the susceptibility of IAV isolates to oseltamivir (OST), the most widely used NAI drug in the country. Initially, we analyzed 282 influenza A(H1N1)pdm09 and 455 A(H3N2) genetic sequences available on GISAID. The amino acid substitution (AAS) NA:S247N was detected in one A(H1N1)pdm09 strain. We also identified NA:I222V (n = 6) and NA:N329K (n = 1) in A(H3N2) strains. In addition, we performed a molecular screening for NA:H275Y in 437 A(H1N1)pdm09 samples, by pyrosequencing, which revealed a single virus harboring this mutation. Furthermore, the determination of OST IC50 values for 222 A(H1N1)pdm09 and 83 A(H3N2) isolates revealed that all isolates presented a normal susceptibility profile to the drug. Interestingly, we detected one A(H3N2) virus presenting with PA:E119D AAS. Moreover, the majority of the IAV sequences had the M2:S31N adamantanes resistant marker. In conclusion, we show a low prevalence of Brazilian IAV strains with NAI resistance markers, in accordance with what is reported worldwide, indicating that NAIs still remain an option for the treatment of influenza infections in Brazil. However, surveillance of influenza resistance should be strengthened in the country for improving the representativeness of investigated viruses and the robustness of the analysis.

A(H3N2) antigenic variation of influenza is associated with low vaccine efficacy in the early 2018 influenza season in Mexico City.

OBJECTIVES: We evaluated the VE and the mutations of the viruses present in the Mexican population at the beginning of 2018. METHODS: We diagnosed influenza in outpatients with a high-performance Rapid Influenza Diagnostic Test (RIDT) qRT-PCR. Descriptive statistics were used to describe the study population, while the chi-square test was used to determine clinical variables. VE was analyzed through a negative test design. We sequenced the hemagglutinin (HA) gene, performed a phylogenetic analysis, and analyzed the nonsynonymous substitutions both in and outside antigenic sites. RESULTS: Of the 240 patients analyzed, 42.5% received the trivalent vaccine, and 37.5% were positive for influenza. The VE for the general population for any influenza virus type or subtype was 37.0%, while the VE for the predominant influenza A(H3N2) subtype was the lowest (19.7%). The phylogenetic analysis of HA showed the co-circulation of clades and subclades 3C.2a1, 3C.2a1b, 3C.2a2, 3C.2a2re, 3C.2a3, and 3C.3a with identities approximately 97-98% similar to the vaccine composition. CONCLUSION: Low VE was related to the co-circulation of multiple clades and subclades of influenza A(H3N2), with sufficient genetic and phenotypic distance to allow for the infection of vaccinated individuals.

Phototherapies for erythema multiforme secondary to viral infections: A case report of a child.

INTRODUCTION: Erythema multiforme (EM) is a reactive mucocutaneous disorder typically initiated by viral infections. Although the management of EM differs according to the clinical course and trigger factor, it is not clear whether antiviral suppressive therapies may be useful in cases related to such infections. Moreover, the treatment is most often based on supportive care directed towards only the symptoms. AIM: To present a clinical case of a child in which antimicrobial photodynamic therapy (aPDT) and photobiomodulation therapy (PBMT) were used for orofacial manifestations of EM secondary to viral infections. CASE REPORT: A Brazilian 1-year-old boy was admitted to an ICU due to a severe Influenza A H3N2 infection, pneumonia with pleural effusion, and sepsis. About 10 days later, it was noted bleeding lip lesions covered by crusts and bleeding tongue lesions, diagnosed as EM secondary to both H3N2 and herpes simplex virus infections, confirmed by serology tests. A combination of an aPDT session and six PBMT sessions was proposed and resulted in almost complete resolution of the lesion on the 7th day. CONCLUSION: Given the complexity of the present case, the combination of phototherapies seems to be a promising tool for treating acute orofacial mucosal lesions of viruses-induced EM. More studies, however, are needed to reach a definite conclusion.

Influenza A virus circulation in backyard animals in the Pacific coast of Guatemala, 2013-2014.

Due to their documented epidemiological relevance as hosts for influenza A viruses (IAV), humans, poultry and pigs in backyard production systems (BPS) within wetlands could be key to the emergence of novel IAV variants able to transmit between humans or animals. To better understand the circulation of IAV at the human-animal interface of BPS within wetlands, we studied IAV in backyard duck flocks and pig herds in the Pacific Coast of Guatemala. From April 2013 to October 2014, we estimated the monthly IAV per cent seropositive and viral positive flocks and herds in two resource-limited communities. We detected antibodies in sera against the IAV nucleoprotein through ELISA. We also detected IAV viral RNA in respiratory (ducks and pigs) and cloacal (ducks) swabs through rRT-PCR directed at the matrix gene. We attempted viral isolation in eggs or MDCK cells followed by sequencing from swabs positive for IAV. During our study period, IAV seropositivity in duck flocks was 38%, and viral positivity was 23% (n = 86 BPS sampled). IAV seropositivity in pig herds was 42%, and viral positivity was 20% (n = 90 BPS sampled). Both flocks and herds had detectable antibodies against IAV mostly year-round, and IAV was detected in several months. We isolated an H3N2 virus from one pig sampled at the end of 2013. Standard nucleotide BLAST searches indicate that the isolated virus was similar to seasonal viruses circulating in humans, suggesting human-to-pig transmission. Our data show concurrent circulation of IAV in multiple species of poultry and pigs that were commingled in rudimentary conditions in proximity to humans, but no significant risk factors could be identified.