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

Abstract

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.

High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico

“…Finally, our RT-PCR results showed that influenza A(H1N1) pdm09 virus was the predominant strain in our population, coinciding with other studies reporting a high circulation of this strain in Mexico during the same period (Baselga-Moreno et al, 2019), while most other Northern Hemisphere countries reported a predominance of influenza AH3N2 virus (Pebody et al 2017;Mira-Iglesias et al 2018;Wu et al 2018;Baselga-Moreno et al, 2019;Flannery et al, 2019). Interestingly, the incidence of influenza B in our study was higher than previous local seasonal averages (Cortes-Alcala et al 2018;Fernandes-Matano et al 2019), but contrasts with official national statistics showing a lower incidence of influenza B during the same period (Secretaria de Salud and Dirección General de Epidemiología, 2017). Perhaps our national reference center receives more cases not detected at other hospitals around the country due to differences in the availability of diagnostic tests, although these discrepancies may also result from variations in influenza virus strains dominance across different regions of Mexico.…”

Multinational modeling of SARS-CoV-2 spreading dynamics: Insights on the heterogeneity of COVID-19 transmission and its potential healthcare burden

“…Some countries such as South Korea, Germany and to some extent the US have enacted massive testing which has shown benefits in reporting the spread of the disease, 38 whilst others countries such as Mexico have enacted a proper sentinel surveillance model because of effectiveness in tracking outbreaks in other respiratory virus infections. 39 It is noteworthy to mention that using only the official reported numbers our model lessens the effect of methodological biases introduced by curating local reporting approaches. An underestimation in the number of active infections arising from the use of potentially under-sampled data 40 could lead to offsets in our forecasted peak date and in the expected number of peak infections.…”

Public health and economic impact of switching from a trivalent to a quadrivalent inactivated influenza vaccine in Mexico

“…Although influenza A viruses predominated in Mexico's recent influenza seasons, 2,5 considerable numbers of influenza B cases were also reported, particularly among children and adolescents. 5 Currently, because TIVs are mainly used in Mexico, adequate protection against influenza B viruses relies on predicting the correct B lineage to include in each season's influenza vaccine. 6 Our public health impact and budget impact analyses showed that switching to QIV, which protects against both B lineages, over six previous influenza seasons in Mexico would have avoided considerable numbers of influenza cases, deaths, and lost workdays, and would have reduced the burden to the healthcare system.…”

“…34 The benefits of QIV for young children may be linked to the relatively high prevalence and considerable morbidity of influenza B infections in this age group. 5,7,35,36 QIV resulted in the most avoided influenza-related events and cost savings in seasons that had higher incidence and greater mismatch between the TIV and the circulating B lineage (particularly 2015/2016, 2013/2014, and 2012/2013). QIV had less public health and economic benefits versus TIV in 2011/2012 and 2014/2015seasons that had lower attack rates and mismatch levels, and was of no benefit at all for the 2010/2011 season when all circulating B strains were of the same lineage as that included in TIV.…”

“…4 Most influenza vaccines in Mexico are trivalent, containing two strains of influenza A (H1N1 and H3N2) and a single B strain. 5 However, since the early 1980s, two genetically distinct lineages of influenza B virus, Yamagata and Victoria, have cocirculated globally. 6 This has complicated the selection of the correct B lineage to include in the trivalent influenza vaccine (TIV) ahead of each season, and has resulted in frequent mismatches between the B lineage in the vaccine and the predominant B lineage in circulation.…”