I

S

T

M

346

ORIGINAL ARTICLE

Acceptability of Hypothetical Dengue Vaccines Among Travelers Christine M. Benoit, BA, ∗1 William B. MacLeod, ScD,†‡ Davidson H. Hamer, MD,†‡§ Carolina Sanchez-Vegas, MD,∗2 Lin H. Chen, MD,||¶ Mary E. Wilson, MD,# Adolf W. Karchmer, MD,¶∗∗ Emad Yanni, MD, MSc, MA,†† Natasha S. Hochberg, MD,§‡‡ Winnie W. Ooi, MD,§§ Laura Kogelman, MD,|||| and Elizabeth D. Barnett, MD∗ ∗

Maxwell Finland Laboratory for Infectious Diseases, Boston Medical Center, Boston, MA, USA; † Center for Global Health and Development, Boston University, Boston, MA, USA; ‡ Department of International Health, Boston University School of Public Health, Boston, MA, USA; § Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston, MA, USA; || Division of Infectious Diseases, Travel Medicine Center, Mount Auburn Hospital, Cambridge, MA, USA; ¶ Harvard Medical School, Boston, MA, USA; # Department of Global Health and Population, Harvard School of Public Health, Boston, MA, USA; ∗∗ Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA, USA; †† Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, Atlanta, GA, USA; ‡‡ Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA; §§ Travel and Tropical Medicine Clinic, Lahey Clinic, Burlington, MA, USA ; |||| Infectious Disease Clinic, Tufts Medical Center, Boston, MA, USA DOI: 10.1111/jtm.12056

See the Editorial by Annelies Wilder-Smith, pp. 341–343 of this issue.

Background. Dengue viruses have spread widely in recent decades and cause tens of millions of infections mostly in tropical and subtropical areas. Vaccine candidates are being studied aggressively and may be ready for licensure soon. Methods. We surveyed patients with past or upcoming travel to dengue-endemic countries to assess rates and determinants of acceptance for four hypothetical dengue vaccines with variable efficacy and adverse event (AE) profiles. Acceptance ratios were calculated for vaccines with varied efficacy and AE risk. Results. Acceptance of the four hypothetical vaccines ranged from 54% for the vaccine with lower efficacy and serious AE risk to 95% for the vaccine with higher efficacy and minor AE risk. Given equal efficacy, vaccines with lower AE risk were better accepted than those with higher AE risk; given equivalent AE risk, vaccines with higher efficacy were better accepted than those with lower efficacy. History of Japanese encephalitis vaccination was associated with lower vaccine acceptance for one of the hypothetical vaccines. US-born travelers were more likely than non-US born travelers to accept a vaccine with 75% efficacy and a risk of minor AEs (p = 0.003). Compared with North American-born travelers, Asian- and African-born travelers were less likely to accept both vaccines with 75% efficacy. Conclusions. Most travelers would accept a safe and efficacious dengue vaccine if one were available. Travelers valued fewer potential AEs over increased vaccine efficacy.

D

engue is the most common mosquito-borne viral disease worldwide, with incidence increasing 50-fold over the last five decades. It is a leading

Current addresses: 1 Pediatric Diabetes and Endocrinology Research, Children’s Hospitals and Clinics of Minnesota, St Paul, MN, USA. 2 Pediatric Infectious Diseases, Miami Children’s Hospital, Miami, FL, USA. Corresponding Author: Elizabeth D. Barnett, MD, Maxwell Finland Laboratory for Infectious Diseases, Boston Medical Center, 670 Albany Street Room 625, Boston, MA 02118, USA. E-mail: [email protected] © 2013 International Society of Travel Medicine, 1195-1982 Journal of Travel Medicine 2013; Volume 20 (Issue 6): 346–351

cause of fever among returned travelers.1 – 5 While community-based vector control measures have the potential to reduce dengue disease burden, in reality these measures have proved difficult to sustain, and vector mosquitoes have spread significantly in recent years. For the individual, avoidance of mosquito bites is the only currently available means of prevention. Several vaccine candidates are being evaluated in clinical trials and may be available within 2–4 years.6 – 11 Vaccine availability, however, does not automatically lead to patient acceptance. Factors influencing willingness to accept vaccines include perceived risk of disease, vaccine effectiveness, and provider recommendation.11 – 17 Barriers to adoption of dengue

347

Acceptability of Dengue Vaccines

were provided. Incidence rates of AEs used for the questionnaire were chosen to be similar to the rates for AEs to other available travel vaccines: severe AEs to YF vaccine and minor events to hepatitis A vaccine. We calculated proportions, means, ratios of acceptance, and 95% confidence intervals (CI). Subjects who declined to provide answers regarding all four hypothetical vaccines were classified as nonresponders and removed from subsequent analyses. We investigated associations between likelihood of acceptance for each hypothetical vaccine and demographic and trip characteristics, including: country and region of birth; gender; age; race/ethnicity; purpose of travel for most recent past trip; prior travel to a dengue-endemic country; history of YF or Japanese encephalitis (JE) vaccination; and history of dengue illness. Continuous variables were compared using the Wilcoxon rank-sum test and categorical variables using chi-square tests for binary responses and Log-binomial regression. A p value of ≤0.05 was considered statistically significant.

vaccines in endemic areas and factors affecting acceptance of dengue vaccines in travelers have been described.18 – 20 It is possible that factors related to acceptance of travel vaccines may differ when compared with those related to acceptance of routine immunizations, but few studies have addressed these issues. One study of travelers who had to make decisions about yellow fever (YF) vaccine showed that age, risk of disease at destination, and provider recommendation influenced vaccine acceptance.21 Study of YF vaccine acceptance may, however, not be representative of acceptance of other travel vaccines because YF vaccine is required for entry to some countries. The aims of our study were to determine acceptability of four hypothetical dengue vaccines with varying vaccine efficacies (VEs) and risk for adverse events (AEs) and to identify traveler characteristics influencing likelihood of vaccine acceptance. Methods Participants were recruited from August 2008 to December 2009 from the five travel clinics of the Boston Area Travel Medicine Network, a research collaboration seeing approximately 7,500 travelers/year in urban, suburban, academic, university-affiliated, and independent facilities. Participants were recruited from two ongoing dengue studies including travelers aged ≥2 years who had previously visited a dengue-endemic area for ≥2 weeks and those with plans for upcoming travel of ≥2 weeks to dengue-endemic areas. Institutional review boards of participating clinics and the Centers for Disease Control and Prevention approved this study. Adult participants gave written informed consent, assent and parental consent were obtained for subjects aged 7 to 17, and parental consent alone for those

Acceptability of hypothetical dengue vaccines among travelers.

Dengue viruses have spread widely in recent decades and cause tens of millions of infections mostly in tropical and subtropical areas. Vaccine candida...
483KB Sizes 0 Downloads 0 Views