What is the vaccine for typhoid?

The most common vaccine for typhoid is a polysaccharide vaccine, which is made from the purified capsular polysaccharide of *Salmonella enterica* serovar Typhi. It is given as a single injection and provides protection for up to three years.

There is also a newer conjugate vaccine, which is made by chemically linking the capsular polysaccharide to a protein carrier. This vaccine is more expensive than the polysaccharide vaccine, but it is also more effective and provides longer-lasting protection. It is given as a series of three injections.

Both the polysaccharide and conjugate vaccines are safe and effective, but the conjugate vaccine is preferred for children under two years of age, people with weakened immune systems, and people who are travelling to areas where typhoid is common.