How long after receiving a live or attenuated typhoid vaccine can you safely kiss someone, especially if they are immunocompromised?

Waiting Period After Typhoid Vaccination Before Kissing

After receiving the live oral typhoid vaccine (Ty21a), you should avoid open-mouth kissing for 2 weeks after vaccination to prevent potential transmission of the vaccine virus, especially if the person you're kissing is immunocompromised. 1

Transmission Risk by Vaccine Type

Live Oral Typhoid Vaccine (Ty21a)

• Shedding: Live organisms have been detected in stool post-immunization 1
• Transmission risk: No reported cases of onward transmission 1
• Precaution period: 2 weeks after vaccination 1
• Specific activities to avoid during this period:
  • Open-mouth kissing
  • Sharing needles, razors, eating utensils
  • Drinking from the same cup
  • Using the same toothbrushes 1

Injectable Typhoid Vaccine (Vi polysaccharide)

• No risk of transmission as it contains only capsular polysaccharide, not live bacteria
• No waiting period required before kissing or close contact with others

Special Considerations for Immunocompromised Contacts

The risk is particularly important when considering contact with immunocompromised individuals. The Advisory Committee on Immunization Practices (ACIP) recommends that vaccine recipients should:

• Consider avoiding close association with and exposure of high-risk persons to their blood and bodily fluids for up to 6 weeks after vaccination 1
• High-risk persons include immunocompromised persons, pregnant or breastfeeding women, and children aged <1 year 1

Comparison with Other Live Vaccines

This precaution is consistent with recommendations for other live vaccines:

• Live Ebola vaccine: Avoid open-mouth kissing for 2 weeks 1
• Live attenuated influenza vaccine: Healthcare workers should avoid contact with severely immunosuppressed patients for 7 days 1

Clinical Decision Algorithm

1. Determine which typhoid vaccine was administered:

   • If injectable Vi polysaccharide vaccine → No waiting period needed
   • If live oral Ty21a vaccine → Continue to step 2

2. Assess immunocompromised status of potential kissing partner:

   • If severely immunocompromised → Wait 6 weeks before close contact 1
   • If mildly/moderately immunocompromised or immunocompetent → Wait 2 weeks before open-mouth kissing 1

3. If oral sores develop after vaccination:

   • Avoid kissing and sharing utensils until sores heal 1

Pitfalls to Avoid

• Don't assume all typhoid vaccines carry the same transmission risk - only the live oral vaccine poses potential risk
• Don't overlook the immunocompromised status of close contacts - they require more stringent precautions
• Don't confuse typhoid vaccine precautions with those for other live vaccines, which may have different waiting periods

The 2-week waiting period represents a cautious approach based on the most recent guidelines from ACIP, which prioritizes protection of vulnerable individuals while allowing for reasonable resumption of normal activities.