Dispatch
Seropositivity for Influenza A(H1N1)pdm09 Virus among Front Line Health Care Personnel
Article Contents
Abstract
Seroprevalence of antibodies to influenza A(H1N1)pdm09 virus among 193 emergency department health care personnel was similar among 147 non–health care personnel (odds ratio 1.4, 95% CI 0.8–2.4). Working in an acute care setting did not substantially increase risk for virus infection above risk conferred by community-based exposures.New York, New York, was one of the first densely populated areas in the United States to experience outbreaks of A(H1N1)pdm09. These early outbreaks and the concomitant surge in patient volumes in our emergency department (ED) provided the opportunity to evaluate and compare risk for A(H1N1)pdm09 virus infection among front line HCP and non-HCP from the same community in a virus-naive population before availability of the A(H1N1)pdm09 monovalent vaccine.
The Study
HCP who worked in an acute care or specially designated influenza area during April 24–June 11, 2009, were asked to participate in our study during October 28–December 16, 2009, by completing a survey and submitting a blood sample. During the same time, we enrolled a convenience sample of non-HCP adults ≥18 years of age residing in the same region as HCP. None of the participants received the A(H1N1)pdm09 monovalent vaccine before enrollment. Assuming a 20% seroprevalence of antibodies to A(H1N1)pdm09 among the general population and a type I error probability of 5% and type II error probability of 20% (power 80%), a sample size of 140 HCP and 140 non-HCP would be sufficient to show a 15% difference in seroprevalence between HCP and non-HCP.
Serum samples were tested by using hemagglutination inhibition and microneutralization assays with A/Mexico/4108/2009, an A/California/07/2009 (H1N1)–like virus (5). Participants with a single serum sample with a microneutralization titer ≥40 and a hemagglutination inhibition titer ≥20 were considered seropositive for antibodies to A(H1N1)pdm09 virus. This combination of antibody titers in single convalescent serum samples was shown to provide 90% sensitivity and 96% specificity for detection of A(H1N1)pdm09 infection in persons <60 60="60" 92="92" a="a" age="age" and="and" href="http://wwwnc.cdc.gov/eid/article/19/1/11-1640_article.htm#r5" in="in" of="of" persons="persons" specificity="specificity" title="5" years="years">560>
).
Conclusions
Several studies documented reduction in spread of influenza by facemask use and handwashing (13,14). Measures taken to limit the spread of infection during A(H1N1)pdm09 in our hospitals included isolation of patients with ILI upon hospital arrival; HCP use of N95 protective masks, gloves, and gowns; and standard precautions such as handwashing. We did not evaluate the effect of these precautions on risk for A(H1N1)pdm09 virus infection because we did not measure HCP adherence to prevention measures. However, seropositivity for A(H1N1)pdm09 virus might have been higher among HCP in our study if these preventions measures were not in place.
Our study had several limitations. Our control group may not have been representative of the general community. We did not assess for use of influenza antiviral medications after potential exposures among participants. On the basis of our sample size, we only had adequate power to detect a ≥15% difference in seropositivity between HCP and non-HCP. We did not have prepandemic serum samples from study participants to evaluate for pre-existing cross-reactive antibodies to A(H1N1)pdm09 virus. However, we found that that our criteria for seropositivity were highly specific for detection of A(H1N1)pdm09 virus infection.
18>
Dr Alagappan is an emergency physician and Associate Chair of the Department of Emergency Medicine at the North Shore–Long Island Jewish Health System, in New Hyde Park, NY. His research interests include occupational exposure to infectious disease, factors associated with tetanus immunity, and international emergency medicine.
References
- Fraser C, Donnelly CA, Cauchemez S, Hanage WP, Van Kerkhove MD, Hollingsworth TD, Pandemic potential of a strain of influenza A (H1N1): early findings. Science. 2009;324:1557–61. DOIPubMed
- Garske T, Legrand J, Donnelly CA, Ward H, Cauchemez S, Fraser C, Assessing the severity of the novel influenza A/H1N1 pandemic. BMJ. 2009;339:b2840. DOIPubMed
- Chowell G, Bertozzi SM, Colchero MA, Lopez-Gatell H, Alpuche-Aranda C, Hernandez M, Severe respiratory disease concurrent with the circulation of H1N1 influenza. N Engl J Med. 2009;361:674–9. DOIPubMed
- New York City Department of Health and Mental Hygiene. 2009. Health alert #22: novel H1N1 I [cited 2010 Dec 5]. http://www.nyc.gov/html/doh/download/pdf/cd/2009/09md22.pdf
- Veguilla V, Hancock K, Schiffer J, Gargiullo P, Lu X, Aranio D, Sensitivity and specificity of serologic assays for the detection of human infection with 2009 pandemic H1N1 virus in U.S. populations. J Clin Microbiol. 2011;49:2210–5. DOIPubMed
- Zimmer SM, Crevar CJ, Carter DM, Stark JH, Giles BM, Zimmerman RK, Seroprevalence following the second wave of pandemic A(H1N1)pdm09 influenza in Pittsburgh, PA, USA. 2010. PLoS ONE. 2010;5:e11601. DOIPubMed
- Kelly H, Peck HA, Laurie KL, Wu P, Nishiura H, Cowling BJ. The age-specific cumulative incidence of infection with pandemic influenza H1N1 2009 was similar in various countries prior to vaccination. PLoS ONE. 2011;6:e21828. Epub 2011 Aug 5. DOIPubMed
- Chen MI, Lee VJ, Lim W, Barr IG, Lin RT, Koh G, 2009 Influenza A(H1N1) seroconversion rates and risk factors among distinct adult cohorts in Singapore. JAMA. 2010;303:1383–91. DOIPubMed
- Chan YJ, Lee C, Hwang S, Wang F, Ten HT, Tsai C, Seroprevalence of antibodies to pandemic (H1N1) 2009 influenza virus among hospital staff in a medical center in Taiwan. J Chin Med Assoc. 2010;73:62–6. DOIPubMed
- Tandale BV, Pawar SD, Gurav YK, Chadha MA, Koratkar SS, Shelke VN, Seroepidemiology of pandemic influenza A (H1N1) 2009 virus infections in Pune, India. BMC Infect Dis. 2010;10:255. DOIPubMed
- Zhou Y, Ng DM, Seto W-H, Ip DM, Kwok HK, Ma ES, Seroprevalence of antibody to pandemic influenza A (H1N1) 2009 among healthcare workers after the first wave in Hong Kong. J Hosp Infect. 2011;78:308–11. DOIPubMed
- Bandaranayake D, Huang QS, Bissielo A, Wood T, Mackereth G, Baker MG, Risk factors and immunity in a nationally representative population following the 2009 influenza A (H1N1) pandemic. 2010. PLoS ONE. 2010;5:e13211. DOIPubMed
- Cowling BJ, Chan K-H, Fang VJ, Cheun CY, Fung RO, Wai W, Facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial. Ann Intern Med. 2009;151:437–46.PubMed
- MacIntyre CR, Cauchemez S, Dwyer DE, Seale H, Cheung P, Browne G, Face mask use and control of respiratory virus transmission in households. Emerg Infect Dis. 2009;15:233–41. DOIPubMed
Tables
Suggested citation for this article: Alagappan K, Silverman RA, Hancock K, Ward MF, Akerman M, Dawood FS, et al. Seropositivity for influenza A(H1N1)pdm09 virus among front line health care personnel. Emerg Infect Dis [Internet]. 2013 Jan [date cited]. http://dx.doi.org/10.3201/eid1901.111640
No hay comentarios:
Publicar un comentario