Dataset Information

Worldwide transmission and seasonal variation of pandemic influenza A(H1N1)2009 virus activity during the 2009-2010 pandemic.

ABSTRACT:

Background

Seasonal influenza activity varies with geography and time of year.

Objective

To describe how pandemic influenza A(H1N1)2009 [A(H1N1)pdm09] activity varied during the 2009-2010 pandemic.

Methods

We analyzed influenza virological data compiled by the World Health Organization from June 2009-August 2010. We calculated weekly proportions of A(H1N1)pdm09-positive specimens out of all A(H1N1)pdm09-positive specimens detected during the study period for each country. We compared parameters of pandemic activity (e.g., peak A[H1N1]pdm09 weekly proportion [peak activity], number of weeks between the 5th and 95th percentiles of A(H1N1)pdm09 cumulative weekly proportion [duration of activity]) between countries in temperate and tropical-subtropical regions. We quantified the proportion of A(H1N1)pdm09 out of all influenza A specimens by country and correlated it with countries' central latitudes.

Results

We analyzed data from 80 countries (47 temperate, 33 tropical-subtropical). The median proportion of cases identified during the peak week was higher in temperate (0·12) than in tropical-subtropical (0·09) regions (P<0·01). The median duration of activity was longer in tropical-subtropical (27 weeks) than in temperate countries (20 weeks) (P < 0·01). In most temperate countries (98%), peak pandemic activity occurred during the fall-winter period. There was a positive correlation between country central latitude and proportion of A(H1N1)pdm09 out of all influenza A specimens (r: 0·76; P<0·01).

Conclusions

The transmission of A(H1N1)pdm09 exhibited similarities with seasonal influenza transmission in that activity varied between temperate and tropical-subtropical countries and by time of year. Our findings suggest the potential utility of accounting for these factors during future pandemic planning.

SUBMITTER: Storms AD

PROVIDER: S-EPMC4634296 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Publications

Worldwide transmission and seasonal variation of pandemic influenza A(H1N1)2009 virus activity during the 2009-2010 pandemic.

Storms Aaron D AD Van Kerkhove Maria D MD Azziz-Baumgartner Eduardo E Lee Wing-Kei WK Widdowson Marc-Alain MA Ferguson Neil M NM Mounts Anthony W AW

Influenza and other respiratory viruses 20130330 6

<h4>Background</h4>Seasonal influenza activity varies with geography and time of year.<h4>Objective</h4>To describe how pandemic influenza A(H1N1)2009 [A(H1N1)pdm09] activity varied during the 2009-2010 pandemic.<h4>Methods</h4>We analyzed influenza virological data compiled by the World Health Organization from June 2009-August 2010. We calculated weekly proportions of A(H1N1)pdm09-positive specimens out of all A(H1N1)pdm09-positive specimens detected during the study period for each country. W ...[more]

PMID: 23551904

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Project description:During the 2009 influenza pandemic both seasonal and 2009 pandemic vaccines were recommended. We conducted a randomized trial of monovalent 2009-H1N1 vaccine and seasonal trivalent inactivated influenza vaccine (IIV3) given sequentially or concurrently to adults.Adults randomized to 4 study groups and stratified by age (18-64 and ?65 years) received 1 dose of seasonal IIV3 or placebo and 2 doses of 2009-H1N1 vaccine or placebo in one of 4 combinations, i.e., H1N1+Placebo/H1N1+Placebo/IIV3 (HP/HP/V3), H1N1+IIV3/H1N1+Placebo/Placebo (HV3/HP/P), H1N1+Placebo/H1N1+IIV3/Placebo (HP/HV3/P), and IIV3+Placebo/H1N1+Placebo/H1N1 (V3P/HP/H). Intramuscular injections were given three times at 21 day intervals. Sera for antibody assays were obtained prior to and 21 days after each vaccination. Reactogenicity and adverse events were monitored.Eight hundred-five (805) adults were enrolled. All combinations of vaccines were safe and well tolerated. In general, one dose of 2009-H1N1 and one dose of IIV3, regardless of sequence or concurrency of administration, were immunogenic in adults. There were no significant differences in geometric mean titers (GMT) or the proportions of subjects with ?4-fold rise in antibody responses and titers ?40 for any vaccine group or between age strata for 2009-H1N1 after the first or second dose, although the vaccine sequence affected the titers to the IIV3 antigens. Hemagglutination inhibition antibody (HAI) GMTs against 2009-H1N1 for the combined age strata 21 days after the first 2009-H1N1 dose were 190.4, 182.1, 232.9 and 157.5 for HP/HP/V3, HV3/HP/P, HP/HV3/P and V3P/HP/H, respectively. While IIV3 GMTs were adequate they were generally lower than the 2009-H1N1 GMTs. In a subset of subjects, there was good correlation between HAI and microneutralization (MN) titers (Spearman's correlation coefficient 0.92).All vaccine combinations were generally well tolerated. Immune responses to one dose of 2009-H1N1 were adequate regardless of the sequence of vaccination in all age groups, but the sequence affected titers to IIV3 antigens.

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Dataset Information

Worldwide transmission and seasonal variation of pandemic influenza A(H1N1)2009 virus activity during the 2009-2010 pandemic.

Background

Objective

Methods

Results

Conclusions

Publications

Worldwide transmission and seasonal variation of pandemic influenza A(H1N1)2009 virus activity during the 2009-2010 pandemic.

Similar Datasets

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