2.2. Measures

Participants were asked to report their vaccination status for several vaccines recommended for PWUD. Self-reported vaccination status was captured for the Hepatitis A (HAV), Hepatitis B (HBV), Influenza, Measles, Mumps, Rubella (MMR), and Tetanus, Diphtheria, Pertussis (Td/Tdap) vaccines. For each vaccine, participants could respond “Yes, I have received this vaccination”, “No, I have not received this vaccination”, or “I am not sure if I have received this vaccination.” Because individuals who are unvaccinated (“no”) or unsure of their vaccination status (“not sure”) are recommended to seek vaccination counseling [34,35], for the purposes of this analysis we consider the self-reported vaccination proportion to be the proportion of “yes” responses out of all “yes”, “no”, and “not sure” responses, rather than simply comparing “yes” responses to “no” responses. We did not ask if participants were up-to-date on vaccines requiring periodic booster doses (e.g., Tdap) or revaccination (e.g., influenza). For these period vaccines, receipt in lifetime was used as a simple proxy for influenza vaccination history.

The survey also assessed a breadth of sociodemographic and socioeconomic items. Factors used for this analysis included age, race/ethnicity, gender, sexual orientation, education, household income, primary income source, homelessness/housing insecurity, and medical insurance.

This analysis also explores self-reported vaccination status among a few high-risk subpopulations, including participants who had ever traded sex for goods, a place to stay, money or drugs/alcohol, those who had intravenously injected drugs in the past 6 months, and those with histories of incarceration. Intravenous (IV) injection drug use in the past 6 months was determined by aggregating individual items asking participants whether they had used 13 different drug categories in the past 6 months, and to mark the methods by which those drugs were used (IV injection, non-IV injection, orally, nasally, or smoking). Participants were considered to have intravenously injected drugs if they marked “IV injection” to at least one drug category, and to not have intravenously injected drugs if they had a valid response to all 13 drugs and did not mark “IV injection” on any of them. The drug categories assessed included heroin, methadone, opiates/analgesics, barbiturates, sedatives, crack cocaine, powder cocaine, prescription amphetamines, street amphetamines, cannabis, hallucinogens, inhalants, spice, and bath salts.