OPV Can Work in Adults, But IPV is Strongly Preferred Due to Safety Concerns
While OPV can provide effective immunization in adults, inactivated poliovirus vaccine (IPV) is the recommended choice because adults face a slightly higher risk of vaccine-associated paralytic poliomyelitis (VAPP) compared to children. 1, 2
Efficacy in Adults
OPV can generate protective immunity in the adult population and is technically effective:
- OPV produces both systemic and mucosal immunity when administered to adults, similar to its mechanism in children 1
- For adults who previously completed a primary OPV series and require a booster (e.g., travelers to endemic areas), a single dose of OPV can be administered 1
- In urgent situations where less than 4 weeks is available before protection is needed, a single dose of OPV can provide rapid immunity 1
Critical Safety Concerns in Adults
The primary issue is not efficacy but rather an unfavorable risk-benefit profile:
- The risk of vaccine-associated paralytic poliomyelitis is slightly higher in adults than in children receiving OPV 1, 2
- Overall risk remains extremely low: approximately 1 case per 1.4 million first doses and 1 case per 41.5 million subsequent doses in immunologically normal vaccinees 1
- However, given that wild poliovirus has been eliminated from most regions, this small risk is now considered less acceptable 3
When OPV Should NOT Be Used in Adults
Absolute contraindications include:
- Immunocompromised adults (HIV infection, immune deficiency diseases, leukemia, lymphoma, generalized malignancy) 1
- Immunosuppressed adults (corticosteroid therapy, alkylating drugs, antimetabolites, radiation) 1
- Healthcare workers who may shed vaccine virus and expose immunocompromised patients 1
- Laboratory personnel handling poliovirus specimens (risk of viral shedding to contacts) 1
Current Guideline Recommendations
IPV is the preferred vaccine for all adult vaccination scenarios:
- Unvaccinated adults at increased risk should receive a 3-dose IPV primary series (doses at 0,4-8 weeks, and 6-12 months) 2, 4
- Previously vaccinated adults needing a booster receive a single lifetime dose of IPV 2
- Travelers to endemic areas should receive IPV, not OPV 2, 4
Special Circumstance: Pregnant Women
- If immediate protection is needed during pregnancy, OPV (not IPV) is actually recommended despite theoretical concerns 1
- This represents the rare situation where OPV may be preferred over IPV in adults 1
Bottom Line
OPV works immunologically in adults, but the standard of care is IPV for all routine adult vaccination due to the marginally increased VAPP risk and the ability of vaccinated adults to shed live virus that could expose vulnerable contacts 1, 2. The only exception is urgent protection during pregnancy when immediate immunity is required 1.