Why ACIP Recommended Hepatitis A Vaccine for Everyone Experiencing Homelessness

This page summarizes the recommendation the Advisory Committee on Immunization Practices (ACIP) adopted on October 24, 2018, and the figures available at the time. Check CDC for current hepatitis A vaccine guidance.

All persons aged 1 year and older who are experiencing homelessness should be routinely vaccinated against hepatitis A. ACIP adopted that recommendation on October 24, 2018, adding homelessness to the reasons for protecting people against hepatitis A virus (HAV) before exposure.

Who was already covered

Hepatitis A (HepA) vaccine was already recommended routinely for children aged 12–23 months, for anyone wanting immunity, and for people at higher risk of HAV infection:

• international travelers to areas with high or intermediate hepatitis A endemicity;
• men who have sex with men;
• people who use injection or noninjection drugs;
• people with chronic liver disease or clotting factor disorders;
• people who work with HAV-infected primates or with HAV in research laboratories;
• people expecting close contact with an international adoptee from a country of high or intermediate endemicity.

People experiencing homelessness also face a higher risk of infection and of severe outcomes, but were not on the list.

The situation in 2017–2018

Homelessness. In 2017, 1.42 million people in the United States used an emergency shelter or transitional housing at some point in the year. Counting unsheltered people raises the estimate; some studies put the number experiencing homelessness each year at 2.3 million to 3.5 million, with persons of color disproportionately affected. On a single night in 2017, an estimated 553,742 people were homeless, about 35% of them unsheltered. Overall numbers had fallen since 2007, but unsheltered homelessness in major cities had grown. People experiencing homelessness face 1.5 to 11.5 times the mortality risk of the general population, with shorter lives, poor access to care, later diagnosis, more illness and heavier use of acute hospital services, often for preventable conditions.

Outbreaks. HAV spreads mainly by the fecal-oral route, from person to person or through contaminated food or water, and is linked to poor sanitation and hygiene. Crowded living, in shelters or outside them, raises the risk of outbreaks. Recent outbreaks spreading directly between people reporting homelessness marked a shift in U.S. hepatitis A epidemiology:

Why the vaccine fits

• It works well. More than 95% of adults with healthy immune systems develop protective antibodies within 4 weeks of one dose.
• It lasts. Antibodies remain detectable for at least 20 years after childhood vaccination, and modeling suggests 40 years or more. One dose of single-antigen vaccine has shown protection for up to 11 years, and clinical and outbreak experience suggests one dose may protect for life.
• Other protection is hard to come by. Clean toilets, regular handwashing and avoiding crowded living are difficult for many people without homes, so vaccination is the most reliable protection.
• Coverage is low now. Limited access to care and historically low insurance rates leave most adults experiencing homelessness with low coverage for routinely recommended adult vaccines.
• Delivery is possible. Community health centers already provide preventive and primary care to this population, including vaccination, and street- and shelter-based campaigns have vaccinated people efficiently during outbreaks. Thirty-six states and the District of Columbia had expanded Medicaid under the Affordable Care Act, and an estimated 77% of people experiencing homelessness had some form of insurance in 2017.

How the decision was made

From February to October 2018, the ACIP Hepatitis Vaccines Work Group met by monthly conference call and reviewed the evidence using the GRADE framework (Grading of Recommendations Assessment, Development and Evaluation). A literature search covered reports from January 1, 2000, through April 25, 2018.

The evidence was thin. Little is known about HAV seroprevalence among homeless people in the United States, and few studies treated homelessness as a risk factor on its own. The studies reviewed had no control groups and serious risks of bias, inconsistency, indirectness and imprecision; the only one with immunogenicity data in a homeless population was from outside the United States. For both benefits and harms the evidence rated GRADE type 4: clinical experience and observations, observational studies with important limitations, or randomized controlled trials with several major limitations.

The work group also weighed recent outbreaks, hospitalizations and deaths, the cost of liver transplants, and the benefits and costs of vaccination. It concluded that the benefits were substantial, that vaccinating carried far less cost and risk than not vaccinating, and that desirable consequences clearly outweigh undesirable ones in most settings. After public comment, ACIP's voting members approved the recommendation unanimously: 11 in favor, none opposed, abstaining or recused.

In practice

• Schedule: 2 doses, or 3 when the combined hepatitis A and B vaccine is used.
• Start anyway. Worry that a person may be lost to follow-up should not stop the first dose. One dose protects the person and adds to herd immunity, though long-term protection may be less than ideal.
• Everyone who is homeless. Several U.S. definitions of homelessness exist and are similar; the recommendation uses the Department of Health and Human Services definition. Because it is hard to tell what kind of homelessness a person is in, sheltered or unsheltered, all should be vaccinated.
• Use existing services. Routine vaccination through the facilities that already care for homeless people protects individuals and, over time, builds herd immunity that shrinks the at-risk population and the chance of large outbreaks.

Sources

• Doshani M, Weng M, Moore KL, Romero JR, Nelson NP. "Recommendations of the Advisory Committee on Immunization Practices for Use of Hepatitis A Vaccine for Persons Experiencing Homelessness." MMWR 68(6). https://www.cdc.gov/mmwr/volumes/68/wr/mm6806a6.htm
• ACIP evidence tables (GRADE): https://www.cdc.gov/vaccines/acip/recs/grade/table-refs.html