Missed opportunities to vaccinate people at the highest risk for hepatitis B virus (HBV) explain why 80,000 people continue to be infected ever year in the United States, according to a new study published online ahead of print by the journal Infection.

Although there are highly effective vaccines for HBV—GlaxoSmithKline’s Engerix-B and Merck’s Recombivax HB, along with GlaxoSmithKline’s hepatitis A and B combination vaccine TwinRix—Farah Ladak, MD, of Brown University’s Warren Alpert Medical School and her colleagues found that roughly half of a nationally representative sample of high-risk adults hadn’t been immunized. What’s more, they add, the majority of them had potential opportunities to receive the vaccine based on their reported contact with health care providers.

The study is based on responses by more than 15,000 adults who participated in the U.S. Centers for Disease Control and Prevention’s 2007 Behavioral Risk Factor Surveillance Survey, which gathered health information from more than 430,000 people across the United States. The respondents included in the analysis both definitively knew their HBV infection status at the time of the survey and acknowledged engaging in behaviors associated with an increased risk of acquiring hepatitis B; notably they were injection drug users, men who have sex with other men, health care professionals, and people with histories of other sexually transmitted infections and large numbers of sex partners.

Ladak and her colleagues set out to determine who among this highly vulnerable population was going unvaccinated and whether and where they could have received the three required shots.
In general, 51.4 percent of the high-risk adults in the survey remained unvaccinated against HBV infection. Vaccination rates were highest among health care workers and lowest among those with risk factors related to sex or injection drug use.

The researchers found that vaccinations were relatively infrequent among adults older than 33—vaccinations have increased markedly in children since the 1990s—among people with less access to health insurance, and among people who have also not been vaccinated against other diseases such as pneumonia and influenza.

But even among people with access to health care, including people who reported specific contact with health care providers, thousands of people went unvaccinated. Places where improved vaccine delivery could greatly increase immunization rates, the authors suggest, include HIV testing sites, private doctors’ offices, hospitals or clinics and, notably, drug treatment centers and prisons.

According to an analysis by Ladak’s team, 71 percent of survey responders who agreed to HIV testing while in prison went without HBV vaccination. The same was found for 66 percent of people tested for HIV through drug treatment facilities. “Given that many states have mandates to vaccinate incarcerated individuals,” Ladak said in a Brown University news announcement, “you wonder why in so many of these prisons people have not received vaccinations.”

Ladak and her colleagues note that their study lends additional support to the urging of the Institute of Medicine, which in a 2010 report emphasized the importance of seizing opportunities to vaccinate people for hepatitis B and C. The report suggested that, perhaps because the infections sometimes don’t present any symptoms, officials have not devoted enough resources to vaccination programs—and that failure is a reason for the continued prevalence of the diseases.