Hepatitis A infections occurred almost exclusively among adults in states with outbreaks.
Vaccination efforts have lead to a reduction in hepatitis A outbreak-affected states, and this progress should be encouraged to continue, according to the US Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.
Investigators from the CDC analyzed data around 33 eligible hepatitis A outbreak-affected states in order to characterize the demographic, risk factor, and clinical outcome data between 2016 and 2020. Since the introduction of the hepatitis A vaccine in 1996, rates of infection in the US have declined about 97 percent through 2015, the study authors said. However, they noted outbreaks reported in 37 states, accounting for about 44,650 cases, 27,250 hospitalizations, and 415 deaths. Many of these infections occurred among persons who reported injection or non-injection drug use or who were experiencing homelessness, according to a 2017, the study authors also noted.
Of the infected individuals, 56 percent reported drug use, 14 percent reported experiencing homelessness, 12 percent reported recent incarceration, and 3 percent reported recent international travel, the study authors found. They also noted that 5 percent of males with hepatitis A infection identified as men who have sex with men. Additionally, they determined that 61 percent of persons with hepatitis A were hospitalized and there were 380 outbreak-associated deaths, or about 1 percent.
A majority of the hepatitis A cases were among males (62 percent) and white individuals (81 percent), the study authors said. Most of the cases were among those aged 30 to 49 years, and the median age was 38 years, the study authors reported.
Hepatitis B and hepatitis C virus past or current infection was found in 5 and 30 percent of patients with that data available, respectively, the study authors observed.
The study authors wrote that vaccination is the most effective method to prevent and control hepatitis A outbreaks, which lead to the Advisory Committee on Immunization Practices (ACIP) in 2019 recommending that those who experience homeless should be vaccinated, as well as reinforcing vaccination recommendations for drug users. Since then, the number of states with outbreaks has dropped from 37 to 13, the study authors noted.
“Increased hepatitis A vaccination coverage, particularly through implementation of successful, nontraditional vaccination strategies among disproportionately affected populations, is needed to continue progress in halting current outbreaks and preventing similar outbreaks in the future,” the study authors wrote.
In 2017, the CDC launched a large-scale, multidisciplinary response to encourage hepatitis A vaccination in disproportionately affected communities, including hosting satellite vaccination clinics (including at correctional facilities, substance use treatment facilities, syringe services programs, and homeless shelters), and broadening the scope of health care professionals permitted to administer the vaccines. The study authors also described how the CDC also partnered with longstanding organizations who had relationships with people at risk for hepatitis A to overcome barriers to vaccination such as mistrust, stigma, and vaccine hesitancy. These outreach programs have contributed to 24 states declaring their outbreaks over, and a decrease in case counts in the remaining 13 states, the study authors wrote.
“Increased hepatitis A vaccination coverage, through implementation of nontraditional vaccination strategies to reach disproportionately affected populations, along with improved universal and catch-up childhood vaccination, will be necessary to respond to the current hepatitis A outbreaks and prevent similar outbreaks in the future,” the study authors concluded. “Continued improvements in vaccination infrastructure, immunization information systems, and education and outreach are critically needed to build vaccine confidence and improve vaccine delivery in nontraditional settings.”