Accelerated hepatitis B vaccine schedule boosts completion rates in IDUs

The proportion of injecting drug users who receive all three doses of the hepatitis B vaccine can be increased using an accelerated vaccination schedule, US investigators report in the November 15^th edition of the Journal of Infectious Diseases.

A small monetary incentive was provided to encourage individuals to attend so the three doses of the vaccine could be administered.

“Straightforward payment for receipt of immunizations may be not only ethically sound but also an economically sensible way to use public health resources,” comment the investigators.

Injecting drug users are one of the groups most affected by hepatitis B. The virus is highly infectious, especially in the acute phase, and long-term infection can lead to serious health problems including cirrhosis, liver failure and liver cancer.

A vaccine against hepatitis B is available. Vaccination programmes targeted at the groups most at risk of hepatitis B have helped reduce the incidence of the infection in the US. The vaccine is normally provided in three doses over a six-month period.

However, the proportion of drug users who have received the vaccine is low in comparison to other groups.

Therefore investigators from the Drugs, AIDS, STDs, and Hepatitis (DASH) project wished to see if accelerating the vaccination schedule helped improve vaccination rates.

Mindful that HIV and hepatitis C vaccines may be available in the future, they also wanted to see if providing  enhanced information about the benefits of vaccination, and giving individuals a small cash incentive to be vaccinated helped to boost immunisation rates.

Patients were followed up at regular intervals for two years, and they were monitored to see if they developed levels of antibodies that were sufficient to protect them against hepatitis B.

The study population included 1260 drug users. All were negative for both HIV and hepatitis B.

They were randomised into one of four arms:

• Standard hepatitis B vaccination schedule (month 0, month 1, month 6) and standard health information about HIV.

• Standard hepatitis B vaccination schedule and enhanced health information focusing on the efficacy and benefits of immunisation against hepatitis B.

• Accelerated hepatitis B vaccination schedule (month 0, month 1, month 2) and standard health information.

• Accelerated vaccine and enhanced health information.

Overall, 75% of individuals received all three doses of the vaccine. This included 73% of those who received the vaccine over a six-month period, and 77% of individuals who were given the accelerated course of immunizations. The difference in immunisation adherence rates between the two schedules was not significant.

But the researchers then restricted their analysis to injecting drug users. This showed that accelerating the vaccination course did increase completion rates (75% vs 66%, p = 0.04).

However, there was no evidence that providing enhanced health information helped to boost vaccination rates.

Other factors associated with completing the course of immunisations included age over 40 (p < 0.01), African American race (p = 0.03), having stable accommodation, and drinking alcohol (p = 0.02).

Use of speedball – an injected mixture of heroin and cocaine – was associated with poorer completion rates (p < 0.01), as was being homeless on the street (p = 0.02).

Information on response to the vaccine was available for 707 patients. After twelve months of follow-up 65% had developed the minimum antibody level to protect them against hepatitis B.

At six months, individuals who had received all three accelerated doses were significantly more likely than those awaiting their third dose in the standard vaccination regimen to have protective antibodies against hepatitis B (62 vs 49%).

“The results of this study indicate that providing monetary incentives at each visit, free vaccinations, and a shorter vaccination schedule may encourage adherence, particularly among the highly at risk group of IDUs [injecting drug users],” write the authors.

They conclude that their research “serves as a model for a future HIV or hepatitis C vaccine trials and provides information on the effectiveness of accelerated vaccination schedules for increasing immunization among drug users”.