Typhoid Vaccine and Transient Neutropenia
Based on available guideline evidence, transient neutropenia is not a recognized adverse effect of typhoid vaccination. The documented adverse reactions to typhoid vaccines do not include hematologic abnormalities such as neutropenia.
Documented Adverse Effects of Typhoid Vaccines
Inactivated (Parenteral) Typhoid Vaccine
- Local and systemic reactions are the primary adverse effects, including 1-2 days of injection site discomfort, fever, malaise, and headache 1
- These reactions are common but self-limited 1
Oral Live-Attenuated Ty21a Vaccine
- Gastrointestinal symptoms are the main adverse effects, occurring at a rate of <1/100,000 doses administered 1
- Reported reactions consist of nausea, abdominal cramps, vomiting, and skin rash or urticaria 1
Important Distinction: Typhoid Disease vs. Typhoid Vaccine
Neutropenia in Typhoid Fever (The Disease)
It is critical to distinguish between adverse effects of the vaccine versus manifestations of typhoid fever infection itself:
- Neutropenia occurs in typhoid fever disease (the actual infection with Salmonella typhi), found in approximately 25% of patients 2
- Leucopenia is present in only 20-25% of typhoid fever cases, contrary to older beliefs that it was a common finding 2, 3
- The mechanism involves hemophagocytosis in bone marrow, where histiocytes phagocytize neutrophils, red blood cells, and platelets 3
No Evidence Linking Vaccine to Neutropenia
- No guideline or regulatory documentation lists neutropenia as an adverse effect of either inactivated or oral typhoid vaccines 1, 4
- The comprehensive ACIP recommendations from multiple years consistently document only local reactions, fever, and gastrointestinal symptoms—never hematologic abnormalities 1
Clinical Context from Case Reports
One isolated case report describes a patient with pre-existing chronic neutropenia and hypogammaglobulinemia who experienced temporary improvement (not worsening) of neutropenia following typhoid vaccine administration, with enhanced neutrophil release from bone marrow under the stress of vaccination 5. This represents the opposite effect and occurred in a patient with underlying immunodeficiency.
Clinical Recommendation
If neutropenia develops temporally after typhoid vaccination, alternative etiologies should be investigated, as this is not a recognized vaccine adverse effect. Consider:
- Concurrent viral infections
- Medication effects from other agents
- Underlying hematologic conditions
- Coincidental timing with unrelated causes
The absence of neutropenia from all major guideline documents and adverse event reporting systems strongly suggests this is not a vaccine-related phenomenon 1, 4.