What is typhoid vaccine given for?
Typhoid vaccines protect against typhoid fever or enteric fever.

What are the types of typhoid vaccine?
Vi antigen vaccine: It is an inactivated vaccine available as injectable form.
Oral ty21a vaccine: This is an oral live vaccine.

How are the typhoid vaccines available?
The Vi antigen vaccine is available as single dose ready to use vials containing 0.5 ml of vaccine or as multidose bulbs containing 4—10 doses (2—5 ml) depending on brand used. Some brands are available as 0.5 ml containing monodose prefilled syringes. The ty21a oral vaccine is available as a pack of 3 capsules.

How are the typhoid vaccines given?
Vi antigen vaccine is given in the dose of 0.5 ml intramuscularly either on thigh or arm. It is given as a single dose.

Oral ty21a vaccine is a course of 3 capsules given orally on alternate days. The capsules should be swallowed intact & not opened or chewed. In most, the pack contains 4 capsules and such 4 capsules are given on alternate days. Liquid form of oral ty21a vaccine in sachet form is more effective than the capsule form. But sachet form is not available in India.

When is the typhoid vaccine given?
Typhoid fever can occur at any age. 10% of cases occur in infants< 1 year of age. The most common group to be affected is school going children and adolescents. Hence earlier the vaccine is given better it is.

The Vi antigen vaccine can be given only after completing 2 years of age. Oral ty21a vaccine is in form of capsules and the capsules need to be swallowed intact. Though the vaccine is effective after 2 years of age, practically a child above 4—6 years of age can swallow capsules. Hence it is recommended after the age of 4—6 years.

What is the efficacy to typhoid vaccine?
The protective efficacy lasts for 2-3 years in most of the vaccinees following 1 dose of Vi vaccine or 3 doses of ty21a vaccine. If one gives 4 capsules of oral ty21a vaccine, it will lead to protection for 3-5 years. Hence one has to revaccinate every 3 years.

What are the side effects of typhoid vaccines?
Vi antigen vaccine: It can lead to local side effect like pain, swelling, redness, tenderness etc. The side effects are very mild and are seen in < 10% of vaccinees, last for 24 hours & respond to paracetamol. Systemic side effects are rarely seen & include mild fever lasting for 24 hours, which responds well to paracetamol.

Oral ty21a vaccine: It leads to mild GI discomfort like pain in abdomen, vomiting, diarrhea & occasionally mild fever. Again, the reactions are less common, mild and self-limiting.

Who should be given the typhoid vaccine?
Typhoid is an endemic disease in India with estimated incidence of 5 million cases per annum. The currently available vaccines are safe and efficacious. It must be given to all food handlers, travelers to endemic areas, those who eat outside open food frequently. It should also be given to those who have suffered typhoid fever as typhoid does not lead to protective immunity & relapses are known to occur. In such cases, it is given 4 weeks after complete recovery from typhoid fever.

What are the contraindications to typhoid vaccine?
Oral ty21a vaccine is contraindicated in immune compromised host, as it is a live vaccine. Antibiotics that act against typhoid should not be given 5 days before, during & after vaccination with oral ty21a vaccine. Lastly, any child who has shown severe reactions to previous typhoid vaccine should not be given the same vaccine again.

Can typhoid vaccine be given along with other vaccine?
Typhoid vaccine can be given along with other vaccine using separate syringe and separate site.