Ty21a is a vaccine that protects against typhoid. It is one of two vaccine currently recommended by the World Health Organization. The vaccine offers between 33 and 78% protection. The vaccine is most commonly used to protect travellers to endemic countries, but there's no reason why the vaccine couldn't be used in large scale public prevention programmes. The vaccine is given by mouth. The vaccine is presented either as capsules or a liquid suspension. The vaccine must be stored at 2 to 8… (More on Ty21a)