tetano
Editor, Senior Moderator
Arch Med Res. 2014 Nov 13. pii: S0188-4409(14)00228-8. doi: 10.1016/j.arcmed.2014.11.005. [Epub ahead of print]
Intense Seasonal A/H1N1 Influenza in Mexico, Winter 2013-2014.
D?vila-Torres J1, Chowell G2, Borja-Aburto VH1, Viboud C3, Grajalez-Mu?iz C4, Miller MA3.
Author information
Abstract
BACKGROUND AND AIMS:
A recrudescent wave of pandemic influenza A/H1N1 affected Mexico during the winter of 2013-2014 following a mild 2012-2013 A/H3N2 influenza season.
METHODS:
We compared the demographic and geographic characteristics of hospitalizations and inpatient deaths for severe acute respiratory infection (SARI) and laboratory-confirmed influenza during the 2013-2014 influenza season compared to previous influenza seasons, based on a large prospective surveillance system maintained by the Mexican Social Security health care system.
RESULTS:
A total of 14,236 SARI hospitalizations and 1,163 inpatient deaths (8.2%) were reported between October 1, 2013 and March 31, 2014. Rates of laboratory-confirmed A/H1N1 hospitalizations and deaths were significantly higher among individuals aged 30-59 years and lower among younger age groups for the 2013-2014 A/H1N1 season compared to the previous A/H1N1 season in 2011-2012 (χ2 test, p < 0.001). The reproduction number for the winter 2013-2014 influenza season in central Mexico was estimated at 1.3-1.4, in line with that reported for the 2011-2012 A/H1N1 season but lower than during the initial waves of pandemic A/H1N1 activity in 2009.
CONCLUSIONS:
We documented a substantial increase in the number of A/H1N1-related hospitalizations and deaths during the period from October 2013-March 2014 in Mexico and a proportionate shift of severe disease to middle-aged adults, relative to the preceding A/H1N1 2011-2012 season. In the absence of clear antigenic drift in globally circulating A/H1N1 viruses in the post-2009 pandemic period, the gradual change in the age distribution of A/H1N1 infections observed in Mexico suggests a slow build-up of immunity among younger populations, reminiscent of the age profile of past pandemics.
Copyright ? 2014 IMSS. Published by Elsevier Inc. All rights reserved.
KEYWORDS:
A/H1N1 influenza pandemic; Age distribution; Drift; Immunity; Influenza vaccine; Transmissibility
PMID:
25446618
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25446618
Intense Seasonal A/H1N1 Influenza in Mexico, Winter 2013-2014.
D?vila-Torres J1, Chowell G2, Borja-Aburto VH1, Viboud C3, Grajalez-Mu?iz C4, Miller MA3.
Author information
Abstract
BACKGROUND AND AIMS:
A recrudescent wave of pandemic influenza A/H1N1 affected Mexico during the winter of 2013-2014 following a mild 2012-2013 A/H3N2 influenza season.
METHODS:
We compared the demographic and geographic characteristics of hospitalizations and inpatient deaths for severe acute respiratory infection (SARI) and laboratory-confirmed influenza during the 2013-2014 influenza season compared to previous influenza seasons, based on a large prospective surveillance system maintained by the Mexican Social Security health care system.
RESULTS:
A total of 14,236 SARI hospitalizations and 1,163 inpatient deaths (8.2%) were reported between October 1, 2013 and March 31, 2014. Rates of laboratory-confirmed A/H1N1 hospitalizations and deaths were significantly higher among individuals aged 30-59 years and lower among younger age groups for the 2013-2014 A/H1N1 season compared to the previous A/H1N1 season in 2011-2012 (χ2 test, p < 0.001). The reproduction number for the winter 2013-2014 influenza season in central Mexico was estimated at 1.3-1.4, in line with that reported for the 2011-2012 A/H1N1 season but lower than during the initial waves of pandemic A/H1N1 activity in 2009.
CONCLUSIONS:
We documented a substantial increase in the number of A/H1N1-related hospitalizations and deaths during the period from October 2013-March 2014 in Mexico and a proportionate shift of severe disease to middle-aged adults, relative to the preceding A/H1N1 2011-2012 season. In the absence of clear antigenic drift in globally circulating A/H1N1 viruses in the post-2009 pandemic period, the gradual change in the age distribution of A/H1N1 infections observed in Mexico suggests a slow build-up of immunity among younger populations, reminiscent of the age profile of past pandemics.
Copyright ? 2014 IMSS. Published by Elsevier Inc. All rights reserved.
KEYWORDS:
A/H1N1 influenza pandemic; Age distribution; Drift; Immunity; Influenza vaccine; Transmissibility
PMID:
25446618
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25446618