Does a 6-year-old patient, who is up-to-date with Tetanus, Diphtheria, and Pertussis (TDAP) vaccine, require an additional vaccination after a mild superficial scratch by a cat?

No Additional Tetanus Vaccination Needed

A 6-year-old patient who is up-to-date with TDAP vaccination does not require additional tetanus vaccination after a mild superficial cat scratch on the scalp. 1, 2

Wound Classification

• A mild superficial cat scratch is classified as a clean, minor wound rather than a contaminated/tetanus-prone wound 1
• While cat scratches can introduce bacteria through saliva, a superficial scratch on the scalp without deep tissue penetration or significant contamination does not meet criteria for a tetanus-prone wound 1
• Contaminated/tetanus-prone wounds typically include deep puncture wounds, wounds contaminated with dirt/soil/feces, or wounds with devitalized tissue 1

Vaccination Algorithm for Clean, Minor Wounds

For patients with ≥3 previous doses (which an up-to-date 6-year-old would have):

• No tetanus vaccination is needed if the last dose was <10 years ago 1, 3
• A 6-year-old who is up-to-date would have received their most recent DTaP dose at age 4-6 years, well within the 10-year window 1
• The CDC explicitly states that adults and children who completed primary vaccination and received a tetanus-containing vaccine <10 years ago are protected and do not require additional vaccination for clean, minor wounds 1

Critical Time Intervals to Remember

• Clean, minor wounds: Booster needed only if ≥10 years since last dose 1, 3
• Contaminated/tetanus-prone wounds: Booster needed if ≥5 years since last dose 1, 3
• This patient's superficial scratch falls into the first category 1

Important Clinical Caveat

• Even though a case report exists of tetanus occurring after cat scratches in a previously immunized patient 4, this represents an extremely rare occurrence
• The patient in that case report had "mild and recurrent cat scratch and bites" with symptoms appearing 7 weeks later, suggesting deeper or more extensive wounds than a single superficial scratch 4
• The severity of tetanus disease is modulated by previous vaccination, and properly immunized patients have significantly milder disease if it occurs at all 4

Common Pitfall to Avoid

• Do not confuse the 10-year routine booster interval with the 5-year interval for contaminated wounds - this is the most common error in tetanus prophylaxis 1
• More frequent doses than recommended may increase the risk of adverse reactions, including Arthus-type hypersensitivity reactions 1

When Vaccination WOULD Be Indicated

• If this were a deep puncture wound from a cat bite (rather than superficial scratch): vaccination would be needed if ≥5 years since last dose 1, 2
• If the patient had <3 lifetime doses or unknown vaccination history: both tetanus vaccine AND TIG would be required 1, 3
• If the patient were severely immunocompromised: TIG would be indicated regardless of vaccination history 1