Drug users often are at higher risk of preventable infections such as hepatitis A virus (HAV), hepatitis B virus (HBV), and tetanus and should be important targets for vaccinations, according to new research.

That is according to a recent study in Therapeutic Advances in Infectious Disease. Researchers from the Department of Pharmacy at Oregon Health & Science University in Portland pointed out that rates of serious injection-related infections in persons who use drugs have increased. “Resulting admissions are an opportunity for screening and vaccination of preventable infections such as hepatitis A virus (HAV), hepatitis B virus (HBV), and tetanus,” the researchers added.

The study team conducted a retrospective review of adults with documented substance use admitted for bacterial infection between July 2015 and March 2020, evaluating HAV, HBV, and tetanus vaccination status at admission, along with screening for HAV and HBV infection and immunity. The proportion of patients at risk for infection who received HAV, HBV, and tetanus vaccines during admission and patient-level factors associated with vaccination were quantified.

With 280 patients meeting inclusion criteria:

• 198 (70.7%) patients were at risk for HAV. Infectious disease providers recommended HAV vaccination for 21 (10.6%) and 15 (7.6%) patients
• 174 (62.1%) patients were at risk for HBV. Infectious disease providers recommended HBV vaccination for 32 (18.3%) and 25 (14.4%) patients
• A large proportion of patients (88, 31.4%) had no documentation of prior tetanus vaccination, and infectious disease providers recommended tetanus booster vaccination for three (1.1%) and five patients (1.8%).

“Infectious disease consult vaccine recommendations were statistically significantly associated with HAV or HBV vaccination prior to discharge,” the researchers explained.

The authors cautioned, “Over 70% of our population is at risk for one or more of these preventable infections. Efforts are needed to maximize inpatient screening and vaccination for HAV, HBV, and tetanus in patients with barriers to care.”

Patients with substance use disorders (SUD) are at risk for serious bacterial infections, according to background information in the report. In addition to substance use itself, the authors added, patients with SUD have higher rates of unstable housing, are more commonly members of vulnerable groups, and are less likely to have access to health insurance or primary care providers.

Despite recommendations for HAV immunization for adults at risk, since 2016 several outbreaks have been reported, with substance abusers and the homeless at the highest risk. “The outbreaks have resulted in 44,209 infections, including 27,018 (61%) hospitalizations and 420 deaths as of April of 2022,” according to the report. “There are ongoing outbreaks in eight states in the United States, with Georgia and Indiana reporting the highest number of cases (2,118 and 2,657, respectively), with 14% of this population experiencing homelessness. Homelessness was added to the recommendations for HAV vaccination in 2019, intending to increase herd immunity over time, as gaps in vaccination have been identified.”

The trends are similar with HBV. “The most common risk behavior reported is injection drug use,” the researchers advised. “Despite this known risk, people who use substances currently exhibit low rates of HBV immunity (<40%), with a significant increase in HBV infections in this population over the last two decades. Importantly, in 2022, the Advisory Committee on Immunization Practices expanded recommendations to include universal HBV vaccination of adults aged 19–59 years, supported by significant cost-utility data.”

The study team added that for wound management, which is common in people who inject drugs, a second dose of tetanus/diphtheria or tetanus/diphtheria/pertussis is safe at 5-year intervals.

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