641. Cumulative Incidence Estimates of Medically Attended Seasonal Influenza from 2011-2016 for the Central Texas Baylor Scott & White Health - Temple Population Research Area (BSWH-TPRA).
Session: Poster Abstract Session: Oh, Those Pesky Viruses!
Thursday, October 27, 2016
Room: Poster Hall
  • Cumulative Incidence - IDWeek 2016_vs1.0.pdf (553.0 kB)
  • Background: Severity and burden of influenza can be estimated with the cumulative incidence of lab-confirmed influenza among medically-attended acute respiratory illnesses (MAARI) during local circulation.

    Methods: BSWH is one of 5 CDC US Flu Vaccine Effectiveness network sites since 2011. The BSWH-TPRA source population was defined as residents from zip codes within East Bell County, Central Texas (CTX), who have seen a primary care provider for any reason in the past 3 years. We enrolled outpatients with acute respiratory illness of ≤7 days, with cough and tested nasal-throat swabs for influenza A&B by RT-PCR. Vaccination was verified with electronic records. We divided the population into 4 age strata and 2 vaccination statuses. Within each stratum and status, we formed 3 subgroups based on number of MAARIs: (None, 1, and ≥2). Applying proportions observed in the enrollees, we estimated the cumulative incidence of medically-attended seasonal influenza.


    Table: Cumulative Incidence of Seasonal Influenza in the BSWH-TPRA 2011-12 to 2015-16.

    Influenza Season (Severity)

    Percentages of predominant Influenza Type, A Subtype and B lineage in enrollees

    Cumulative Incidence

    % (95% CI)

    2011-12 (Mild)

    A (H1N1)pdm09 (84%)

    0.72% (0.53-0.92)

    2012-13 (Moderately-severe)

    A (H3N2) (51%), B-Yamagata (36%), B-Victoria (10%)

    5.95% (5.52-6.38)

    2013-14 (Moderate)

    pH1N1 (77%)

    2.44% (2.12-2.77)

    2014-15 (Moderately-severe)

    A (H3N2) (75%)

    4.14% (3.73-4.55)

    2015-16 (Moderate)

    A (H1N1)pdm09 (27%), B-Victoria (46%)

    2.61% (2.23-2.99)

    The highest incidence during 2011-12, 2012-13 and 2014-15 was among persons ages 6 months - 8 years, 1.61%; 95% CI (0.88-2.33%), 8.96%; 95% CI (7.48-10.43%) and 7.27%; 95% CI (5.83-8.72%) respectively. During 2013-14, it was among those ages ≥50 years: 2.79%; 95% CI (2.17-3.42%) and during 2015-16, it was seen among those 9 years -18 years: 5.05%; 95% CI (3.91-6.19%).

    Conclusion: The cumulative incidence of medically-attended influenza in 2013-14, when the burden of A (H1N1)pdm09 shifted to those aged ≥50 years was higher than in 2011-12. The highest incidence was seen in 2012-13 season when A H3N2 and both B-lineages circulated. Influenza immunization programs should especially target age-groups 6 months to 18 years and ≥50 years.

    Manjusha Gaglani, MBBS1, Kempapura Murthy, MBBS, MPH2, Jessica Pruszynksi, Ph.D3, Lydia Clipper, RN3, Anne Robertson, AA4, Pedro Piedra, MD5 and Archana Nangrani, MBBS4, (1)Pediatrics, Baylor Scott & White Health, Texas A&M HSC COM, Temple, TX, (2)Academic Operations Research Development, Baylor Scott & White Health, Temple, TX, (3)Academic Operations, Baylor Scott & White Health, Temple, TX, (4)Baylor Scott & White Health, Temple, TX, (5)Baylor College of Medicine, Houston, TX


    M. Gaglani, None

    K. Murthy, None

    J. Pruszynksi, None

    L. Clipper, None

    A. Robertson, None

    P. Piedra, None

    A. Nangrani, None

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