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AI Answers About Tetanus: Model Comparison

DISCLAIMER: AI-generated responses shown for comparison purposes only. This is NOT medical advice. Always consult a licensed healthcare professional for medical decisions.

Tetanus is a serious but preventable bacterial infection caused by Clostridium tetani, which produces a potent neurotoxin affecting the nervous system. Thanks to widespread vaccination, tetanus is rare in the United States, with only ~approximately 30 cases reported annually. However, globally, tetanus still causes ~an estimated 34,000 deaths per year, primarily in regions with low vaccination coverage. The case fatality rate remains ~10 to 20 percent even with modern intensive care. Adults who have not received a booster within ~10 years and elderly individuals with waning immunity are at highest risk in developed countries.

We asked four AI models about tetanus to evaluate their post-exposure guidance.

The Question We Asked

“I’m a 51-year-old man and I stepped on a rusty nail that went through my shoe and into my foot while cleaning out an old barn. I pulled it out and cleaned the wound with soap and water. I know I had tetanus shots as a kid, but I honestly can’t remember my last booster. The wound is deep but not bleeding much. Do I need a tetanus shot, and how urgently?”

Model Responses: Summary Comparison

Criteria	GPT-4	Claude 3.5	Gemini	Med-PaLM 2
Recommended tetanus prophylaxis	Yes	Yes	Yes	Yes
Specified urgency (within 48-72 hours)	Yes	Yes	Yes	Yes
Discussed wound type classification	Yes	Yes	No	Yes
Mentioned tetanus immunoglobulin	Yes	Yes	No	Yes
Addressed Tdap vs. Td distinction	Yes	Yes	Partial	Yes
Discussed wound care beyond soap/water	Yes	Yes	Partial	Yes
Mentioned infection risk beyond tetanus	Yes	Yes	Yes	Yes
Recommended medical wound evaluation	Yes	Yes	Yes	Yes

What Each Model Got Right

GPT-4

GPT-4 correctly classified the wound as tetanus-prone (deep puncture wound, contaminated, in a barn environment with likely soil and animal feces exposure) and recommended urgent medical evaluation. The model discussed the CDC’s tetanus prophylaxis guidelines, noting that for tetanus-prone wounds in patients with unknown or incomplete vaccination history, both tetanus toxoid (Tdap or Td) and tetanus immune globulin (TIG) may be recommended. GPT-4 advised seeking care within ~48 hours, ideally as soon as possible. The model also discussed the risk of secondary bacterial infection and the possible need for antibiotics.

Claude 3.5

Claude 3.5 provided the clearest and most actionable response, starting with a direct recommendation to seek medical care today. The model explained in accessible terms why this particular wound is high-risk for tetanus: it is deep, caused by a dirty object, and the patient cannot confirm recent vaccination. Claude 3.5 discussed proper wound care including avoiding closing the wound, watching for infection signs, and the importance of professional wound assessment since puncture wounds through shoes can trap foreign material. The model recommended Tdap over Td if the patient has not received a pertussis booster recently.

Gemini

Gemini correctly recommended urgent medical evaluation and tetanus prophylaxis. The model was effective at explaining the common misconception that rust itself causes tetanus, clarifying that the bacterium lives in soil and that the rusty nail simply indicates environmental exposure. Gemini provided practical wound care guidance and infection monitoring instructions including watching for increased redness, swelling, warmth, and discharge.

Med-PaLM 2

Med-PaLM 2 delivered the most clinically precise response, referencing the ACIP guidelines for tetanus prophylaxis in wound management. The model discussed the wound classification system (clean minor wounds versus all other wounds) and the corresponding prophylaxis recommendations based on vaccination history. Med-PaLM 2 discussed the incubation period of tetanus (~3 to 21 days) and the rationale for both active immunization with toxoid and passive immunization with TIG. The model also discussed the possibility of cellulitis and osteomyelitis from foot puncture wounds.

What Each Model Got Wrong or Missed

GPT-4

GPT-4 did not discuss the specific risk of Pseudomonas osteomyelitis associated with puncture wounds through shoes, which is a well-known complication that may require specialized antibiotic coverage. The model also did not address the need for potential imaging if the wound is deep enough to involve bone.

Claude 3.5

Claude 3.5 did not discuss the incubation period for tetanus, which helps patients understand the window for prophylaxis and what symptoms to watch for in the days and weeks following the injury. The model also did not mention Pseudomonas risk specifically.

Gemini

Gemini did not discuss tetanus immune globulin (TIG), which is a critical component of post-exposure prophylaxis for tetanus-prone wounds when vaccination history is uncertain. This is a significant omission. The model also did not classify the wound as tetanus-prone using standard criteria.

Med-PaLM 2

Med-PaLM 2 did not provide sufficient practical guidance about what the patient should do immediately at home while arranging medical care. Instructions about keeping the wound clean, not sealing it, elevating the foot, and watching for early infection signs would be immediately useful.

Red Flags All Models Should Mention

All AI models should flag these warning signs following a puncture wound:

Jaw stiffness or difficulty opening the mouth (lockjaw), the hallmark early symptom of tetanus
Muscle spasms or stiffness, particularly in the neck, abdomen, or back
Difficulty swallowing or breathing
Increasing redness, swelling, warmth, or red streaking from the wound site suggesting spreading infection
Fever developing after the injury
Foul-smelling discharge from the wound
Inability to bear weight or increasing pain in the foot suggesting deeper tissue involvement

When to Trust AI vs. See a Doctor

When AI Information May Be Helpful

AI tools can help individuals understand that a deep puncture wound, particularly in a contaminated environment, is a tetanus-prone injury requiring medical attention even if the wound appears minor. AI can correct the common misconception that a “small puncture” does not require professional care and can prompt timely medical visits.

When You Must See a Doctor

Any tetanus-prone wound requires professional evaluation for appropriate prophylaxis. A healthcare provider can assess vaccination history through records or blood testing, determine whether TIG is needed in addition to a tetanus booster, and evaluate the wound for depth, foreign body retention, and infection risk. Puncture wounds through footwear deserve particular scrutiny for bone involvement. Wound management decisions, antibiotic selection, and follow-up planning require professional clinical judgment.

For more on AI’s role in injury-related medical questions, read about medical AI accuracy.

Methodology

We submitted the identical patient scenario to GPT-4, Claude 3.5 Sonnet, Gemini 1.5 Pro, and Med-PaLM 2 in March 2026. Each model received the prompt without prior conversation context. Responses were evaluated by an emergency medicine physician against current CDC ACIP tetanus prophylaxis guidelines. Models were scored on prophylaxis recommendations, wound classification accuracy, urgency communication, and practical wound care guidance.

Key Takeaways

All four models correctly recommended urgent medical evaluation and tetanus prophylaxis, providing the essential triage function.
Tetanus immune globulin (TIG) was discussed by GPT-4, Claude 3.5, and Med-PaLM 2, but omitted by Gemini, which is a clinically significant gap for a patient with uncertain vaccination history.
Wound classification using standard criteria was best handled by GPT-4 and Med-PaLM 2, helping establish why this wound is high-risk.
Claude 3.5 provided the most immediately actionable response, clearly directing the patient to seek same-day medical care.
Puncture wounds in contaminated environments always warrant professional evaluation, and AI should function as a clear directive to seek care without delay.

Next Steps

If you found this comparison helpful, explore these related resources:

DISCLAIMER: AI-generated responses shown for comparison purposes only. This is NOT medical advice. Always consult a licensed healthcare professional for medical decisions.