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Typhoid Vaccine Explained: Defining Sera and Detailing Preparation, Storage, and Dosage Guidelines 2025

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SERA

Immune sera are blood serum samples from an animal (or human) that having the specific antibodies against to a specific antigen, which are developed by the exposure of specific antigen or proteins intensely or some time unintentionally.

• These antibodies utilize for passive immunization by providing immediate protection against the targeted antigen without requiring the recipient to build their own immune response.
• Immune sera provide the quick response against the particular antigen by hamper the antigen effectiveness (by neutralizing the toxic effects of antigen) especially useful in situations where there is an urgent need to neutralize the threat. It also improves the body immunity against any other infections or manifestation.
• Immune sera not provide the long-term effect on the body like vaccines, but provide temporary effects with quick response.

Now a days, it is used for short-term prophylaxis and therapeutically, Common examples include as.

• Tetanus Antitoxin
• Hepatitis B Immune Globulin
• Rabies Immune Globulin
• Immune Serum Globulin (Human)

Common preparation method of Immune Sera:

1. Selection of animal—Numerous animal species like horse, sheep, donkey, goat, and rabbit have been used on the various scales in the sera production. Horse is the animal choice for sera production.
2. Preparation method.

• The neck muscles of horse are injected with toxoid for a few minutes to several months and give first dose not more than 5ml and increased to 600ml to get satisfactory antitoxin titre.
• 8 litres of blood withdrawn from jugular vein into bottles containing anti-coagulant solution. Repeat the bleeding twice for the next 8 days after that give rest for 10 days.
• Give a short course of antigen to stimulate further antibody. Repeat procedure until animal stops producing a satisfactory antitoxin titre (usually 4 to 5 courses).
• Store the collected blood in refrigerator till cells are settled.
• Plasma is siphoned off and calcium chloride is added to induce clotting.
• Clot is separated from the serum by filtration.

3. Refinement of serum

• Concentration by fractional precipitation
• Concentration by proteolytic digestion.

Typhoid vaccine.

Typhoid vaccines are used to prevent typhoid fever, a bacterial infection caused by Salmonella typhi.