二種混合ワクチン（Td：破傷風・ジフテリア）

成人は10年ごとの追加接種。外傷後、前回の接種から5年以上経過している場合に投与。

Severe allergic reaction to previous dose of any tetanus/diphtheria-containing vaccine. History of Arthus-type hypersensitivity reaction after previous dose — defer booster until ≥10 years elapsed. Moderate to severe acute illness (defer). Guillain-Barré syndrome within 6 weeks of previous tetanus-toxoid-containing vaccine (relative contraindication — risk-benefit assessment).

Very common: injection site pain (60–80%), induration, erythema. Common: headache, malaise, fatigue, fever (low-grade). Uncommon: lymphadenopathy, myalgia. Arthus-type reaction: large local swelling extending from shoulder to elbow — associated with hyper-immunization (too-frequent boosting). Rare: peripheral neuropathy, GBS (estimated 0.4/1,000,000 doses). Severe allergic reactions: very rare.

Primary series (never vaccinated adults): 3 doses — 0, 4–8 weeks, 6–12 months. Booster: single 0.5 mL dose IM every 10 years. Wound management booster: 0.5 mL IM if ≥5 years since last tetanus dose (tetanus-prone wound) or ≥10 years (clean wound). Injection: 0.5 mL IM in deltoid muscle. Do NOT administer subcutaneously (reduced immunogenicity and increased local reactions).

Tetanus component: near 100% protection after primary series; neutralizing antitoxin levels ≥0.1 IU/mL considered protective. Diphtheria component: 85–97% efficacy; reduced formulation sufficient for booster response in previously primed individuals. Duration: protective levels persist 10+ years after booster in most individuals.

Store at +2°C to +8°C. Do not freeze (aluminum adjuvant damaged by freezing — shake test if freeze exposure suspected). Protect from light. Shelf life: typically 36 months.

Can be co-administered with all routinely recommended vaccines (influenza, pneumococcal, shingles, hepatitis A/B, COVID-19). No interference with antibody response. No interaction with antibiotics, antivirals, or antimalarials. Immunosuppressive therapy may reduce response — vaccinate when immune function is optimal.

WHO recommends Td (or preferably Tdap) in pregnancy, 2nd or 3rd trimester, to prevent neonatal tetanus. Safe in all trimesters. No teratogenicity. Maternal antibodies provide passive protection to newborn. Breastfeeding: safe.

Not recommended <7 years — use DTaP (pediatric formulation with full-strength diphtheria) for primary series in children. Children ≥7 years who missed primary series: use Td (or Tdap for first dose).

Adequate response in healthy elderly. Consider more frequent antibody checks in immunocompromised elderly, especially post-splenectomy or on immunosuppressive therapy. Booster response may be slower but is generally adequate.

Do NOT shorten booster intervals — hyper-immunization increases Arthus reaction risk. For wound management, prefer Tdap over Td if patient has not received recent pertussis-containing vaccine. Always check vaccination history before administering — unnecessary doses increase adverse events without benefit. Tetanus Immune Globulin (TIG) may be needed concurrently for contaminated wounds in under-vaccinated individuals (different injection site).