Hepatitis B Vaccine Adherence Stronger in 2 Doses Compared to 3

Series completion rates were different among patient groups, the study authors observed.

A 2-dose hepatitis B vaccine had more series completion success compared to a 3-dose vaccine in adults, according to an original investigation published in JAMA Network Open.

Investigators from Kaiser Permanente Southern California compared 2 cohorts of adult hepatitis B virus vaccine in order to determine if 2-dose hepatitis B vaccine recipients were more likely to complete their series compared to 3-dose vaccine recipients. The 2-dose group received cytosine phosphoguanine adjuvant (HepB-CpG vaccine; Heplisav-B) and the 3-dose group received alum adjuvant (comparator vaccine; Engerix-B [HepB-alum]) between August to December 2018, the study authors said. The patients were followed for up to 1 year after the first dose.

The Kaiser Permanente Southern California system employs electronic alerts and reminders for hepatitis B vaccination. The system has recently included to coverage among patients with diabetes and those tested for sexually transmitted infections, study author Katia Bruxvoort, PhD, MPH, research fellow at the Kaiser Permanente Southern California Department of Research & Evaluation, told Contagion. Vaccinations are offered proactively at any care visit, she added, for no cost to their members.

Overall, there were 4727 individuals who received the 2-dose series, of which about 60 percent were ages 40 to 59 years, about half were male, and half of the patients were Hispanic, the study authors said. Similarly, there were 6161 patients who initiated the 3-dose series, of which 61 percent were ages 40 to 59 years, about half were male, and a little less than half were Hispanic.

The study authors determined that the 2-dose cohort completed their series within the recommended schedule, plus 3 months, for 44 percent of individuals. The 3-dose cohort completed their series within the recommended schedule, plus 3 months, for 26 percent of individuals. But for the period of within 1 year after the recommended schedule, the rates of completion for the 2-dose cohort grew to 60 percent and grew to 32 percent in the 3-dose cohort, the study authors found.

“Our study suggests that use of an adult hepatitis B vaccine series with fewer doses is associated with higher series completion,” Bruxvoort said. “This may seem self-evident, but it is important to quantify to inform vaccine decision-making. We did not formally assess reasons for higher series completion in our study, but potential reasons may be that the 2-dose series requires fewer health care visits for vaccination and can be completed within 1 month, as compared to 6 months for 3-dose series.”

The study authors additionally found that in both cohorts, the series completion was lower in Black individuals compared to White patients, and also lower in Hispanic compared to white patients but to a lesser extent. This is consistent with the racial and ethnic disparities noted in other studies that examine adult vaccinations, Bruxvoort said.

“Series completion was also lower among younger adults and those living in census blocks with lower levels of income or education,” she continued. “Previous research has identified barriers to adult vaccination such a underinsurance and concerns about the costs of vaccines, perceptions of low disease risk, and low confidence in vaccines, but further research is needed to better understand how to address these challenges.”

Bruxvoort added that hepatitis B is preventable with a vaccine, but that the 2-dose vaccine had significantly greater and earlier seroprotection compared to the 3-dose vaccine. This could have been due to the adjuvant contained in the 2-dose vaccine. The 2-dose also offers higher rates of protection in patients with diabetes and obesity and in elderly adults.