Typhim Vi is an injectable vaccine that protects against typhoid fever, a potentially serious bacterial infection caused by Salmonella typhi. Made by Sanofi Pasteur, it contains 25 micrograms of purified Vi polysaccharide, a sugar-like molecule found on the outer coating of the typhoid bacterium. When injected, this molecule trains your immune system to recognize and fight the real bacteria if you’re ever exposed.
Who Should Get It
Typhim Vi is approved for anyone age 2 and older. It’s primarily recommended for travelers heading to parts of the world where typhoid is common, particularly South Asia, Southeast Asia, Africa, and parts of Central and South America. People who live with or have close contact with a known typhoid carrier are also candidates, along with laboratory workers who handle Salmonella typhi cultures.
Typhoid spreads through contaminated food and water, so the vaccine is especially important if you’ll be eating or drinking outside of controlled hotel or resort settings. That said, the vaccine isn’t a substitute for careful food and water precautions while traveling.
How It’s Given and When It Works
The vaccine is a single shot, typically given in the upper arm. You need it at least two weeks before your trip so your body has time to build protective antibodies. If you continue traveling to high-risk areas or remain at ongoing risk, a booster dose is recommended every two years.
Unlike the oral typhoid vaccine (Vivotif), which requires four capsules taken over a week, Typhim Vi is a one-visit process. That convenience makes it a practical choice for last-minute travelers, though two weeks of lead time is still necessary.
How Well It Protects You
Typhim Vi offers moderate, not complete, protection. A large systematic review estimated its cumulative efficacy at about 55% over roughly three years. A major trial in Kolkata, India, found a protective effectiveness of 61% among all participants. These numbers mean the vaccine cuts your risk of typhoid roughly in half, which is significant but not foolproof. This is why safe eating and drinking habits remain important even after vaccination.
Protection begins to fade after about two years, which is why the booster schedule exists. If your last dose was more than two years ago and you’re planning another trip to a high-risk area, you’ll need a fresh injection.
Common Side Effects
The most common reaction is soreness or tenderness at the injection site. In clinical trials, nearly all adults (93% to 98%) reported some tenderness within 48 hours. About 27% to 41% described it as actual pain rather than just sensitivity. These local reactions typically resolve within a day or two.
Systemic side effects are less common but do occur. In trials of US adults, headache affected 16% to 20%, general fatigue or malaise hit 4% to 24% depending on the study, and muscle aches showed up in 3% to 7%. Actual fever above 100°F was rare, occurring in roughly 1% of people across all studies.
Children tend to have milder reactions. In a trial of children ages 1 to 12, only about 14% reported pain at the injection site, and fewer than 3% experienced any systemic symptoms like feeling feverish or having reduced energy. Getting a booster dose does not appear to cause significantly worse side effects compared to the first shot, though injection-site pain may be slightly more common the second time around.
Who Should Not Get Typhim Vi
Anyone who had a severe allergic reaction to a previous dose of Typhim Vi or to any component of the vaccine should not receive it again. If you’re currently experiencing a moderate or severe acute illness (beyond a mild cold), vaccination is typically postponed until you’ve recovered. The vaccine is not approved for children under 2 years old.
Typhim Vi vs. the Oral Typhoid Vaccine
Two typhoid vaccines are available in the United States: Typhim Vi (the injectable) and Vivotif (the oral capsule). Both target the same disease, but they work differently and have distinct practical considerations.
- Typhim Vi: One injection, effective in two weeks, approved for ages 2 and up, booster every two years. Can be stored in a standard refrigerator.
- Vivotif: Four capsules taken every other day over one week, effective about one week after the last dose, approved for ages 6 and up, booster every five years. Must be refrigerated and taken on an empty stomach. Because it contains live, weakened bacteria, it’s not appropriate for people with weakened immune systems.
The two vaccines have broadly similar efficacy. Your choice often comes down to practical factors: how soon you’re traveling, your child’s age, whether you prefer a shot or pills, and whether you have any immune system conditions that rule out a live vaccine. Typhim Vi’s single-dose convenience makes it the more popular option for many travelers.
What Typhoid Fever Actually Is
Typhoid fever is a systemic infection that enters the body through the digestive tract and then spreads into the bloodstream. Symptoms typically include sustained high fever, weakness, stomach pain, headache, and loss of appetite. Without treatment, it can lead to serious complications including intestinal perforation. The disease remains a major public health concern in low- and middle-income countries, with an estimated 11 to 21 million cases occurring worldwide each year. Antibiotic resistance in Salmonella typhi is a growing problem in many regions, which makes prevention through vaccination and safe food and water practices all the more important.