The effectiveness of the typhoid vaccine can vary depending on the type of vaccine and the individual.
The typhoid shot. The inactivated typhoid vaccine (Typhoid Vaccine, Inactivated, also known as TIV) is about 50-80% effective in preventing typhoid fever in people who receive the full course of the vaccine. Protection lasts for about 2-5 years but the effectiveness of the vaccine decreases over time, so booster doses may be needed to maintain protection.
Typhoid pills. The live attenuated oral typhoid vaccine (Typhoid Vaccine, Live, Oral, also known as Ty21a or Vivotif) is about 70-80% effective in preventing typhoid fever in people who receive the full course of the vaccine. Protection provided by the oral vaccine lasts for about 5 years since the last dose. It also decreases over time, and booster doses may be needed to maintain protection. The efficacy of the typhoid vaccine was shown through numerous tests in the 80s and 90s. These tests were controlled trials where outcomes were compared between placebo group and the vaccinated group. The placebo group typically acquired typhoid at 2x the rate of the vaccinated. In one of the experiments, they actually exposed all the participants to typhoid after receiving the vaccine. This experiment also proved successful.
It's important to note that the vaccine will not provide complete protection, and there is still a risk of contracting the disease even after vaccination. It is also important to note that the vaccine may not be as effective in certain populations, such as people with weakened immune systems or in areas with high levels of antibiotic resistance.
If you think you may have typhoid fever, it's important to seek medical attention as soon as possible. Here are some steps you can take:
Contact your doctor: Schedule an appointment to see your doctor as soon as possible. If you are traveling abroad, it's important to seek medical attention from a qualified healthcare professional who is familiar with the disease and the local healthcare system.
Describe your symptoms: Be sure to provide your doctor with a detailed description of your symptoms, including when they started and any other related health issues.
Provide your travel history: Let your doctor know if you have recently traveled to an area where typhoid fever is common, as this can be a risk factor for the disease.
Get tested: Your doctor may order tests such as blood culture, PCR, or ELISA to confirm the diagnosis of typhoid fever.
Start treatment: If you test positive for typhoid fever, you will be prescribed antibiotics to treat the infection. It's important to take the antibiotics as directed and complete the full course of treatment.
Prevent spreading: To prevent the spread of the disease to others, practice good hygiene, such as washing your hands frequently and avoiding close contact with people who are sick.
Follow-up: Follow up with your doctor as directed and let them know if your symptoms do not improve or if new symptoms develop.
It's important to note that prompt diagnosis and treatment is crucial for a successful outcome. If left untreated, typhoid fever can cause serious complications and even death.
For a review of efficacy evidence of the oral typhoid vaccine, see:
Amicizia D, Arata L, Zangrillo F, Panatto D, Gasparini R. Overview of the impact of Typhoid and Paratyphoid fever. Utility of Ty21a vaccine (Vivotif®). J Prev Med Hyg. 2017 Mar;58(1):E1-E8. PMID: 28515625; PMCID: PMC5432773.