Typhoid fever is a serious bacterial infection caused by Salmonella Typhi that can lead to high fever, weakness, stomach pain, headache, and loss of appetite. This illness spreads through contaminated food and water, often in areas with inadequate sanitation and hygiene. Vaccination plays a significant role in preventing typhoid, especially for individuals traveling to or living in regions where the disease is common. While treatment with antibiotics is available, vaccination helps safeguard public health and reduce severe illness.
Duration of Oral and Injectable Vaccines
The protection offered by typhoid vaccines varies by type. The injectable inactivated polysaccharide vaccine, known as ViCPS or ViPS, is given as a single intramuscular dose and is approved for individuals aged two years and older. It typically provides protection for about two to three years.
The oral live-attenuated vaccine, known as Ty21a, involves taking four enteric-coated capsules, with each capsule taken every other day. The series should be completed at least one week before potential exposure. This vaccine generally offers protection for five to seven years.
Factors Influencing Vaccine Protection
While typhoid vaccines provide a general duration of protection, several individual factors can influence how long this immunity lasts. A person’s immune response plays a significant role, as not everyone responds to vaccines in the same way. Age can also be a factor, with some studies indicating that younger children, particularly those under two years old, might have a less robust or shorter-lived protective response to certain typhoid vaccines.
Underlying health conditions can also affect vaccine efficacy. Individuals who are immunocompromised due to illness or medications, such as those on high-dose steroids or chemotherapy, may not achieve the same level or duration of protection from the live-attenuated oral vaccine. The level and frequency of exposure to Salmonella Typhi bacteria can also influence the duration of protection. Continuous or repeated exposure may necessitate more frequent re-vaccination to maintain adequate immunity.
When to Get a Booster and Travel Advice
Booster doses are recommended for both types of typhoid vaccines to maintain protection. For the injectable ViPS vaccine, a booster is generally advised every two to three years if there is an ongoing risk of exposure to Salmonella Typhi, especially for those who frequently travel to endemic regions.
For the oral Ty21a vaccine, re-vaccination with the entire four-dose series is typically recommended every five years for individuals with continuous or recurring exposure. Travelers should consult a healthcare provider or a travel clinic well in advance of their trip to discuss their specific vaccination needs. This allows sufficient time for the vaccine to become effective and for any necessary booster doses to be administered based on the destination’s risk level and the traveler’s medical history.