A single center, prospective cohort, open-label study of rabies post exposure program with equine rabies immunoglobulin (ERIG) and purified chick-embryo cell (PCEC) rabies vaccine in WHO category III exposed patients at Siriraj Hospital, Thailand aims to compare serum RVNA responses between obese (BMI > 30 kg/m2) and normal weight/underweight (BMI < 25 kg/m2) and to evaluate adverse events occurring after immunization on days 7, 14 and 28.

A single center, prospective cohort, open-label study of rabies post exposure program with equine rabies immunoglobulin (ERIG) and purified chick-embryo cell (PCEC) rabies vaccine in WHO category III exposed patients at Siriraj Hospital, Thailand aims to compare serum RVNA responses between obese (BMI > 30 kg/m2) and normal weight/underweight (BMI < 25 kg/m2) and to evaluate adverse events occurring after immunization on days 7, 14 and 28.

Inclusion Criteria:

1. Male or female ages of >= 18 years and older;
2. Experienced WHO category III rabies exposure excluding presenting wound at eye(s) or eye lid(s);
3. Either a) obese with BMI >= 30 or b) normal weight and/or underweight with BMI < 25;
4. Agree to independently consent to participate in all study procedures.

Exclusion Criteria:

1. Positive skin test to ERIG or known hypersensitivity to ERIG or its excipients;
2. Co-enrolment with other studies or participated in other investigational drug studies or use of other investigational drugs within 4 weeks or five times the half-life of the investigational drug;
3. Female patients who are currently pregnant or breast feeding.
4. Presenting with wound at eye(s) or eye lid(s);
5. Receiving rabies vaccination more than 7 days for this exposure;
6. History of complete pre-exposure or post-exposure regimen with at least 3 doses;
7. Known of allergic to egg or poultry meat;
8. History of previous exposure to equine sera
9. Significant illness that might harm or increase the risk to the patients;
10. History of drug abuse or alcoholism.

No plan to provide individual participant data (IPD). However, other researcher could request IPD from principal investigator.