Syringe access, disposal and recovery to protect the public's health

View or download full article: https://escholarship.org/uc/item/2r7298jr

Abstract

Public health principles are based on promoting dignity, equity and compassion for all. San Francisco has made great strides towards “Getting to Zero” HIV infections, deaths, and stigma. However, we face new challenges with persons who inject drugs (PWID), and increases in substance use disorder, mental illness, and homelessness. Residents and visitors are concerned about (a) an increase in people injecting drugs in public and (b) an increase in discarded syringes on the streets of San Francisco. Some have asked whether syringe access programs are distributing too many syringes, and whether this poses a health risk to the general public. This brief reviews the science behind syringe access programs and how they protect the public’s health. To protect the public’s health, San Francisco’s deploys a collective impact approach to (a) reduce syringe sharing, infection, and disease prevalence (by syringe access); (b) reduce contact with discarded syringes (by syringe disposal and recovery); and (c) prevent and reduce needlestick injury harms (occupational safety and health).

Executive summary

  1. Public health principles are based on promoting dignity, equity and compassion for all.
  2. San Francisco has made great strides towards “Getting to Zero” HIV infections, deaths, and stigma. However, we face new challenges with persons who inject drugs (PWID), and increases in substance use disorder, mental illness, and homelessness.
  3. Residents and visitors are concerned about (a) an increase in people injecting drugs in public and (b) an increase in discarded syringes on the streets of San Francisco.
  4. Some have asked whether syringe access programs are distributing too many syringes, and whether this poses a health risk to the general public. This brief reviews the science behind syringe access programs and how they protect the public’s health.
  5. First, adhering to U.S. Public Health Service and California Department of Public Health (CDPH) policy guidelines, San Francisco deploys a needs-based syringe access program because it is the best evidence-based practice that reduces syringe sharing and reuse among PWID, thereby (a) reducing the acquisition and prevalence of HIV, hepatitis B (HBV), and hepatitis C (HCV), and (b) reducing other complications (e.g., soft tissue infections). CDPH recommends against more restrictive or untested syringe access policies (e.g., “one-to-one” or “one-to-one-plus” syringe exchange).
  6. Second, keeping the prevalence of infections in PWID as low as possible reduces the risk of infection to health care workers, street cleaning and maintenance workers, and the general public should they experience an unintentional needlestick injury.
  7. Third, syringe pollution is a serious problem that is best addressed with a comprehensive syringe disposal and recovery program to reduce contact with discarded syringes. Fortunately, the risk of acquiring HIV infection from a needlestick from a discarded syringe is exceedingly rare (1/1 million to 75/1 million). Furthermore, less than 10 cases of HIV or HCV have been documented from all western countries since 2008.
  8. In summary, to protect the public’s health, San Francisco’s deploys a collective impact approach to (a) reduce syringe sharing, infection, and disease prevalence (by syringe access); (b) reduce contact with discarded syringes (by syringe disposal and recovery); and (c) prevent and reduce needlestick injury harms (occupational safety and health).

Introduction

At the San Francisco Department of Public Health our approach to addressing substance use, substance use disorder, and infectious diseases is based on (a) the principles of primary prevention, harm reduction, univeral access to services, scientific evidence, and guidance by community lived experience and wisdom, and (b) the universal values of dignity, equity, compassion, and humility. For example, using this approach, San Franciso has made great strides towards “Getting to Zero” HIV infections, deaths, and stigma (see Figure for new HIV diagnoses and HIV deaths). A key component of our comprehensive strategy is our longstanding syringe access, disposal and recovery program. Likewise, the number of new HIV infection diagnoses in persons who inject drugs (PWID) has also decreased (Figure ).

New HIV diagnoses (NHIV) and deaths (HIVD), San Francisco, 2006--2016. In 2016, there were 223 new HIV infections and 165 HIV deaths.

Figure 1: New HIV diagnoses (NHIV) and deaths (HIVD), San Francisco, 2006–2016. In 2016, there were 223 new HIV infections and 165 HIV deaths.

New HIV diagnoses among persons who inject drugs, San Francisco, 2006--2016.

Figure 2: New HIV diagnoses among persons who inject drugs, San Francisco, 2006–2016.

However, we face new challenges with persons who inject drugs (PWID), and increases in substance use disorder, mental illness, and homelessness.

  • Residents and visitors are concerned about (a) an increase in people injecting drugs in public and (b) an increase in discarded syringes on the streets of San Francisco.

  • Some have asked whether syringe access programs are distributing too many syringes, and whether this poses a health risk to the general public. This paper reviews the science behind syringe access programs and how they protect the public’s health.

Concepts for protecting and promoting health

How does syringe access, disposal, and recovery work together to protect health? Four groups (in four settings) are at risk for infections from syringes that has been used by a PWID.

  1. Persons who inject drugs exposed by sharing syringes
  2. Health care workers exposed by needlesticks in health care settings
  3. Street cleaning and maintenance (SCM) workers with occupational exposures to discarded syringes
  4. General public in contact with discarded syringes

For group \(i\), where \(i =\) 1, 2, 3, or 4, the risk of infection (\(R_i\)) depends on the following:

  • Contact (\(c_i\)) rate of needlestick injuries
  • Probability (\(P\)) that a PWID is infected with a bloodborne pathogen1
  • Probability (\(q_i\)) of infection given needlestick with syringe from an infected PWID2

Therefore, over a year, for a random individual from group \(i\), the risk of infection is

\[ R_i = c_i P q_i \]

This equation is deceptively simple and informative. For all groups the infection risks depend on the prevalence of infections (HIV, HBV, HCV) in PWID. Infected PWID are the “source” of infection for all groups (Figure ). The key drivers of infection risk are PWID prevalence of infections, PWID syringe sharing (\(c_1\)), and health care worker needlesticks (\(c_2\)). Because infection risks from discarded syringes are extremely low (very low \(q_3\) and \(q_4\)), contact with discarded syringes in the community are not drivers of infection risk. Less than 10 cases of HIV or HCV have been documented from all western countries since 2008.

Four groups are at risk for acquiring infections from needlestick injuries: (1) persons who inject drugs by sharing syringes, (2) health care workers, (3) SCM workers, and (4) the general public.  Each arrow represents the causal risk relationship ($R_i = c_i P q_i$).  The risks to non-health care workers (arrow 3) and the general public (arrow 4) are extremely low.

Figure 3: Four groups are at risk for acquiring infections from needlestick injuries: (1) persons who inject drugs by sharing syringes, (2) health care workers, (3) SCM workers, and (4) the general public. Each arrow represents the causal risk relationship (\(R_i = c_i P q_i\)). The risks to non-health care workers (arrow 3) and the general public (arrow 4) are extremely low.

Therefore, the most important driver of infection from a needlestick is the probability that the “source” of the syringe (a PWID) is infectious with a bloodborne pathogen. We estimate this probability by the prevalence of infections (HIV, HBV, and HCV) in PWID. PWID are the most important risk group to prevent infections because they (a) have the highest risk of becoming infected (b) are the source of infection for all risk groups.

View or download full article: https://escholarship.org/uc/item/2r7298jr

Footnotes


  1. The first approximation is the prevalence of infection. For PWID, prevalence is the number of infected PWID divided by the total number of PWID.

  2. Also called the transmission probability.

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