Rabies is a fatal viral disease that afflicts both humans and animals. Rabies virus infects the central nervous system and causes inflammation of the brain, also known as encephalitis. An infection of rabies almost always leads to death. However, there is still hope in the form of rabies antiserum treatment which can save lives if administered promptly.

Post Exposure Prophylaxis
Post exposure prophylaxis (PEP) refers to the immediate medical treatment given to a person who has been exposed to rabies through a bite, scratch or lick on broken skin or mucous membranes by a suspected rabid animal. The key components of PEP include thorough wound cleansing, rabies vaccine and rabies immunoglobulin (rabies antiserum).

Role of Rabies Antiserum
Rabies antiserum or rabies immunoglobulin is a product manufactured from the antibodies of animals (such as horses or humans) that have been immunized against rabies. It contains high levels of rabies virus-neutralizing antibodies. Rabies antiserum provides an immediate, passive and short-term protection against rabies by neutralizing the virus at the site of exposure, until the body manufactures its own antibodies in response to vaccination. Rabies antiserum is recommended for all category III exposures as per World Health Organization guidelines.

Administration of Rabies Antiserum
Rabies antiserum is administered at multiple sites around the wound along with rabies vaccine. For bite wounds, antiserum is infiltrated around the entire wound border. For non-bite exposures like scratches or licks on broken skin, antiserum is infiltrated around the exposure site. It is important that antiserum infiltration is done within hours of exposure for it to be most effective. Rabies antiserum provides protection for 2-3 weeks, which allows sufficient time for active immunity to develop in response to vaccination.

Sources of Rabies Antiserum
Several countries produce rabies antiserum under good manufacturing practices. The two most commonly used worldwide are Purified Equine Rabies Immunoglobulin (PERIG) produced in Argentina and Human Rabies Immunoglobulin (HRIG) produced in various countries. PERIG is purified from the blood plasma of horses that have been hyperimmunized with rabies vaccines. HRIG is purified from the plasma of human donors with high titers of rabies neutralizing antibodies. Both have proven safety and efficacy as recommended by WHO.

Ensuring Adequate Supply
Rabies being a fatal yet entirely preventable disease, ensuring adequate availability of rabies antiserum is crucial for effective rabies control. While production depends on collection of plasma from immunized animals or humans, procuring enough quantity remains a challenge in some low and middle-income countries. International organizations work with national authorities to improve supply chain management, increase domestic production capacity and facilitate procurement through pooled funding mechanisms for countries in need. Stockpiling antiserum at regional and district levels is also recommended to guarantee timely administration in case of exposure.

Effectiveness of PEP Including Antiserum
Prompt administration of complete post exposure prophylaxis including thorough wound cleaning, rabies vaccination and infiltration of antiserum around the exposure site is highly effective in preventing rabies. Correct use of PEP has proven to be over 99% effective in preventing rabies in exposed persons if treatment is initiated before symptoms occur. This clearly establishes the critical role played by each component, including antiserum in saving lives from this otherwise fatal disease. There has never been a verified case of rabies in a human who received proper PEP, including antiserum after a risk exposure.

Addressing Challenges to Access
While rabies antiserum is undoubtedly a life saving biologic, certain challenges exist in ensuring its equitable access to all exposed persons who need it. Limited production capacity and high costs are key barriers to wider availability especially in resource poor settings. Lack of clinical guidelines, training of health staff and community awareness programs pose additional hurdles. Concerted advocacy efforts are underway to prioritize rabies on national health agendas and mobilize resources for improving domestic production infrastructure. Adoption of cost effective post exposure regiments using antiserum continues to expand accessibility to this lifesaving treatment.

Conclusion
Rabies antiserum remains the most critical element in preventing rabies death in a person exposed to a rabid animal. While challenges persist in its supply, efforts are ongoing to strengthen production, procurement, distribution mechanisms and programmatic implementation of comprehensive PEP. With international collaborations supporting national response capacities, the goal of universal access to timely and appropriate post exposure prophylaxis, including rabies antiserum, can become a reality. This will ensure no one dies of this preventable disease due to lack of effective prevention and care.