Rabies Post-Exposure Prophylaxis: The Evidence Behind the Pathway

A 30-year-old woman weighing 60 kg arrives in the casualty an hour after a monkey bit her forearm outside a temple. There are three small punctures with a little bleeding. She is four months pregnant, and she wants to know two things: does she really need the injections, and will they harm the baby? This is an illustrative case, not a real patient.

By the end of this article you will know how to categorise her bite and what to do in the first fifteen minutes. You will also know how much immunoglobulin she needs, and what to tell her about the pregnancy.

1. Which Animal, Which Category

“Can we not just watch the monkey for ten days?” No. The standard 10-day observation period applies strictly to domestic dogs and cats. A monkey bite is treated as a Category III exposure. Monkey bites and scratches are among the commonest exposures presenting in Indian cities and temple towns, and the 10-day observation period does not apply to them.

The tool sets out the other animals the same way. Wild animals are universally treated as Category III. Domestic rodents do not ordinarily require PEP, but forest rodents do. Bats are the one place where the national and the international documents part company:

Where the bite was abroad, or the species is uncertain, the tool treats it as Category III. Our patient’s bite broke the skin and drew blood, from a monkey: Category III.

2. The First Fifteen Minutes: Wash the Wound

Before any decision about vaccine or immunoglobulin, flush the wound thoroughly with soap and running water for 15 minutes, and follow it with a virucidal antiseptic such as povidone iodine or alcohol. This is never skipped for want of stock. It is the one step that is always available, and the one most often hurried.

A bite is a tetanus-prone wound as well as a contaminated one. Decide the tetanus toxoid and immunoglobulin in the tetanus pathway. Consider co-amoxiclav for a bite that is deep, on the hand or the face, or already inflamed.

3. The Immunoglobulin: How Much, and Where

A Category III bite needs passive immunisation as well as the vaccine. The doses the tool prints are: ERIG 40 IU/kg, HRIG 20 IU/kg, Rabishield 3.33 IU/kg, Twinrab 40 IU/kg. For our patient of 60 kg, that is 2,400 IU of ERIG or 1,200 IU of HRIG. It is about 200 IU of Rabishield, or 2,400 IU of Twinrab. Use whichever is in the pharmacy.

“Why is Rabishield so much less?” Because it is a different kind of product. Here are the two monoclonals, with the trials behind them:

The WHO 2018 position paper encourages monoclonal antibody products instead of RIG for passive immunisation, if available. The tool used to give the reason in a sentence:

Monoclonals are made in vitro, so potency holds from batch to batch, there is no blood-borne infection risk, and supply is easier to hold at a lower price.

The caution follows from the table: Rabishield is dosed at 3.33 IU/kg and Twinrab at 40 IU/kg. They are not interchangeable on a per-IU basis. Read the label on the vial in your hand before you calculate.

Whichever product, the principle of infiltration is the same: infiltrate the entire calculated dose directly into and around all wound margins on Day 0. NCDC 2019, which the tool follows, advises giving any remaining volume intramuscularly at a site distant from the vaccine. WHO’s 2018 position is that immunoglobulin beyond the wound margins adds nothing. Where the wounds are too small to take the volume, dilute the dose two to three fold with sterile normal saline, so that every wound is covered. Do not exceed the calculated dose.

“She came on Day 0. What if she had come on Day 10?” Then no immunoglobulin. RIG or RMAb must not be given beyond Day 7 after the first vaccine dose, because it may blunt the developing active immune response.

4. Suturing

Avoid suturing wherever it can be avoided. Where it is surgically unavoidable, clean the wound, infiltrate the immunoglobulin first, and delay the sutures by a few hours (NCDC 2019). Place as few loose sutures as the wound allows.

5. There Are No Contraindications

Now her second question. Rabies, once it declares itself, is close to 100% fatal. Post-exposure prophylaxis is safe in pregnancy, lactation, infancy, old age and concurrent illnesses. So the answer to her is plain: yes, she needs it, and it is safe for her and the baby.

Two more points the tool carries. A patient presenting months or years after the bite is evaluated and treated as if the exposure occurred recently. And in a patient with documented immunodeficiency (HIV, steroids, chemotherapy), RIG or RMAb is given for both Category II and Category III exposures. The vaccine is given only intramuscularly. The antibody titre is estimated 14 days after the course, to decide whether more doses are needed.

6. The Common Mistake

The common mistake is to treat the monkey like a dog: to wait, to watch, and to give the vaccine without the immunoglobulin. It is easy to see why. The ten-day rule is the first thing we learn about rabies, and the monkey ran away. But the rule belongs to domestic dogs and cats alone. A close second is to calculate a monoclonal dose from the wrong product’s figure; the two differ twelvefold.

Back to Our Patient

Her forearm was washed for fifteen minutes with soap and running water and then painted with povidone iodine. Her bite is Category III. She receives the vaccine. On Day 0 she also receives immunoglobulin dosed for 60 kg, from the vial in the pharmacy, infiltrated into and around all three punctures. Her tetanus status is checked. She goes home reassured that none of it harms the pregnancy.

Try This

A 70 kg man was bitten by a stray dog nine days ago. He received his first vaccine dose that day, but no immunoglobulin, because none was in stock. It has arrived today. Should you give it? Illustrative case.

Answer. No. RIG or RMAb must not be given beyond Day 7 after the first vaccine dose. His immune system is already making its own antibody, and the immunoglobulin may blunt it. Complete the vaccine course.

Take-Home Points

• The 10-day observation applies only to domestic dogs and cats; a monkey bite is Category III.
• Wash every bite with soap and running water for 15 minutes before anything else.
• Infiltrate the whole immunoglobulin dose into and around all wound margins on Day 0, and never beyond Day 7.
• Rabishield is 3.33 IU/kg and Twinrab 40 IU/kg: read the vial before you calculate.
• There are no contraindications: pregnancy, infancy and old age included.

Declaration: the author built and maintains the tool. It is free to use. The figures in this article are those the tool carried in its Evidence tab on 5 November 2026, each from the source the tool names. The illustrative cases follow the tool’s rules; check the tool’s result for a real patient.

References

1. Ministry of Health and Family Welfare, Government of India. National Guidelines for Rabies Prophylaxis, 2019. National Rabies Control Programme, NCDC; 2020.
2. World Health Organization. Rabies vaccines: WHO position paper, April 2018. Vaccine. 2018;36(37):5500-3.
3. World Health Organization. Expert Consultation on Rabies, Third report. WHO Technical Report Series, No. 1012; 2018.
4. Gogtay NJ, Munshi R, Ashwath Narayana DH, et al. Comparison of a Novel Human Rabies Monoclonal Antibody to Human Rabies Immunoglobulin for Postexposure Prophylaxis: A Phase 2/3, Randomized, Single-Blind, Noninferiority, Controlled Study. Clin Infect Dis. 2018;66(3):387-395.
5. Kansagra K, Parmar D, Mendiratta SK, et al. A Phase 3, Randomised, Open-Label, Non-inferiority Trial Evaluating Anti-Rabies Monoclonal Antibody Cocktail (TwinRab) Against Human Rabies Immunoglobulin. Clin Infect Dis. 2021;72(12):e667-e675.
6. Gongal G, Sampath G. Monoclonal antibodies for rabies post-exposure prophylaxis: A paradigm shift in passive immunization. Arch Prev Med. 2020;5(1):035-038.