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
Posters
  • 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.

    Results:

    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

    Disclosures:

    M. Gaglani, None

    K. Murthy, None

    J. Pruszynksi, None

    L. Clipper, None

    A. Robertson, None

    P. Piedra, None

    A. Nangrani, None

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.