The Use of Syndromic Surveillance Data For Prevention and Monitoring of Hepatitis A
Authors: Harding Angelique , Schulte Joann , Okulate Olubukunola , Olumuyiwa Tolu , Yang Biru , Salgado Omar 
Published: December 2022

ObjectiveWe describe our efforts to prevent a hepatitis A outbreak in Houston.IntroductionSince 2017, over 11 states have been impacted by outbreaks of hepatitis A among persons experiencing homelessness (PEH) and drug use. The primary methods of transmission for the hepatitis A virus (HAV) are person-to-person contact and ingestion of contaminated foods. The HAV infection typically presents with minor symptoms, but the infection can cause serious complications and death in those with poor health. Houston, TX, the 4th largest U.S. city, has a large, mobile homeless population and is at risk for such an outbreak. Of the US adults surveyed for NHANES, only 27% reported hepatitis A immunity; and the homeless population is considered high risk for acquiring hepatitis A. The Point in Time Homeless Census (2017) estimated 3,412 PEH in the Houston metro area. Nationally, the HAV outbreaks have been marked by high rates of hospitalizations and deaths. Emergency and ambulatory department data was monitored and assessed for HAV-related visits using the Houston Health Department’s (HHD) syndromic surveillance system.MethodsCase reports and syndromic surveillance query were used to assess baseline data. HHD provided single-dose units of Hepatitis A vaccine through the Adult Safety Net program to two community medical providers that deliver care to PEH in Houston. Staff administered vaccines via clinics and outreach efforts. Immunization records were recorded in the state immunization registry. Monitoring of potential outbreaks occurred monthly using the syndromic query. Data from case reports or syndromic surveillance were analyzed once immunization efforts concluded.ResultsFrom 2015-2017, the annual mean of HAV cases reported was 13. Analyses of syndromic surveillance conducted in March and August 2018 revealed no increase in jaundice complaints. Briefings were conducted with multiple stakeholders including community members, medical providers, academia, and health professionals in December 2017. HHD provided 150 single-antigen hepatitis A vaccine allotments to two community partner agencies. Immunizations began in late January 2018; 400 homeless persons had been immunized as of March 30, 2018.ConclusionsOngoing review of surveillance data in conjunction with community assessments of PEH is necessary to prevent a hepatitis A outbreak among PEH in Houston. Since vaccination is cited as the best method of prevention, continuing immunization efforts are needed to build herd immunity.The availability of vaccines was limited due to the increased demand in responding to the multi-state HAV outbreaks. However, Houston Health Department (HHD) had access to doses of the hepatitis A vaccine post Hurricane Harvey. While a mass immunization campaign of at-risk groups would be ideal, staffing isn’t feasible as HHD uses a medical home model for immunization efforts. Innovative public health interventions are required to overcome the inherent challenges of delivering preventive programs to PEH. To prevent a potential HAV outbreak in Houston, comprehensive surveillance strategies should include 1) participatory stakeholder engagement, 2) timely reporting, 3) prompt referrals from providers who care for PEH, 4) community education about transmission and hygiene, and 5) vaccination of at-risk groups to increase herd immunity.