Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Samui.
Last reviewed: October 2026
Yes, the hepatitis A vaccine is recommended for all children travelling to Koh Samui from age 12 months. Thailand sits in a moderate-to-high risk zone for hepatitis A, and the virus spreads easily through food and water, including at beach restaurants, night markets, and waterfall picnic spots. One dose before travel gives strong short-term protection. A second dose, given six to twelve months later, extends that protection for decades.
Your four-year-old is already heading toward the waterfall pool at Na Muang, hands still sticky from mango sticky rice bought at the trailhead stall. That is the best part of a Koh Samui family trip. It is also exactly how hepatitis A reaches children. The virus travels through contaminated food and water, and children are often more exposed than adults simply because they eat without thinking twice.
If your child is 12 months or older and heading to Koh Samui, they need this vaccine. If they are under 12 months, there are still options. And if you have already landed without it, it is not too late. This guide covers every age group, from the family on a two-week beach trip to the expat child who has lived here for a year.
Hepatitis A Risk on Koh Samui: What Parents Should Know
Hepatitis A is a liver infection spread by swallowing tiny amounts of contaminated food or water. In Thailand, the risk is real and ongoing. Children pick it up at beach restaurants where shellfish is not fully cooked, from ice made with untreated water, or from waterfall swimming spots where water quality is never guaranteed.
Koh Samui’s food scene is one of its best features. Night markets in Chaweng and Nathon, beachside barbecues, fresh coconuts, fish markets. For a four-year-old grabbing food with sandy hands after a reef snorkel near Lamai, the risk is much harder to control. Hepatitis A hides in ice, shellfish, salads, and any produce washed in unsafe water. The quality of your resort does not change that.
Symptoms in children include fever, nausea, loss of appetite, dark urine, and jaundice, which is a yellowing of the skin and eyes. Older children tend to get sicker than toddlers, who sometimes show no symptoms at all but can still pass the virus to others. A single vaccine dose before travel removes the risk almost entirely.
Age-by-Age Guide: Which Children Need the Hepatitis A Vaccine
Children 12 months and older
From age 12 months, the hepatitis A vaccine is the standard recommendation for Thailand travel. The schedule is two doses: the first before travel, the second six to twelve months later. One dose gives solid protection for the trip. The second is what locks in long-term, likely lifelong immunity. If your child had the first dose more than a year ago and never had the second, that booster is overdue before Koh Samui.
Infants aged 6 to 11 months
This is where most travel health advice goes quiet. CDC guidance is clear: infants aged 6 to 11 months can receive a hepatitis A vaccine dose before travel to a high-risk destination. The important part is this: that early dose does not count toward the routine two-dose series. Your child will still need the full course from age 12 months. Think of the travel dose as a protective bridge for the trip, not a shortcut through the schedule.
Babies under 6 months
The hepatitis A vaccine is not licensed below 6 months. Babies this young may have some protection from maternal antibodies passed during pregnancy, but this varies and cannot be relied on. For babies under 6 months travelling to a high-risk area, immune globulin, which is a concentrated dose of protective antibodies given by injection, may be an option. This needs a clinical assessment. Doctor Samui can advise on this before your trip or once you arrive on the island.
What If You Are Already on the Island Without the Vaccine?
This is one of the most common questions we hear at our Chaweng clinic: "We landed two days ago. Is it too late?" It is not.
A single hepatitis A dose starts building protection within about two weeks. If you have ten days left on the island, partial protection during that time is still meaningfully better than none. The dose also counts as the first in the two-dose series, so your child’s long-term protection is already underway when you follow up at home.
Doctor Samui offers walk-in vaccination at our Chaweng clinic and can visit your hotel or villa across the island, including Lamai, Bophut, Maenam, and Choeng Mon. You do not need to cut a beach day short to get this sorted.
Hepatitis A Alongside Other Vaccines for a Koh Samui Family Trip
Hepatitis A rarely appears alone on a vaccine list for Thailand. The other vaccines commonly discussed for a Koh Samui family trip are typhoid, rabies, and for longer stays, Japanese encephalitis. Each has its own timing, and getting them right for a child is different from getting them right for an adult.
One thing worth knowing: Twinrix, the combined hepatitis A and hepatitis B vaccine, is only licensed for people aged 18 and over. Children need the standalone paediatric hepatitis A formulation, which in Thailand is typically Havrix Junior or a similar paediatric dose. The dose and volume differ from the adult version. If someone suggests Twinrix for your child, that is the wrong product.
Rabies deserves a specific mention for Samui families. Stray dogs are common across the island, and children tend to run toward them. If your child will be here for more than a few weeks, or if they are the kind of child who greets every dog on the beach, the pre-exposure rabies course is worth discussing. You can find out more about our approach to travel vaccines for children on our family health page. Our team can put together a plan that covers the actual risks of a Koh Samui trip, not a generic Thailand checklist.
Long-Stay Families and Expats: Keeping Kids Up to Date on Koh Samui
If your child lives on Koh Samui, the hepatitis A risk does not go away after the first week. Daily exposure to local food and water means the vaccine matters just as much for expat children as for visitors, arguably more.
Many expat families we see have children with incomplete records: a first dose given back home, a second dose never followed up after the move. Others are unsure what their child has had because records are spread across different countries. Some families assumed the local Thai school vaccination programme covered everything. It does not always include hepatitis A for foreign children.
If you are not sure what your child has had, come in. We can review vaccination records, check what is outstanding, and give missing doses on the same visit.
Checking Your Child’s Vaccination Record Before You Travel
Before any Koh Samui trip, pull out your child’s vaccination booklet or app record and look for two hepatitis A entries. If there is only one, check the date. If it was given more than a year ago, the second dose is overdue. If there are none, your child is unprotected.
Also check that routine vaccines are current: MMR, varicella, and typhoid if you have not already arranged it. A hepatitis A appointment is a good moment to go through the full list with a doctor. Doctor Samui’s family health service is set up for exactly this, whether you are preparing to arrive or sorting things out once you are here.
Doctor Samui offers same-day hepatitis A vaccination for children at our walk-in clinic in Chaweng, with 24-hour hotel and villa visits available across Koh Samui, including Lamai, Bophut, Maenam, Choeng Mon, and Angthong. We see children of all ages, from infants to teens, and can review your child’s full vaccination record on the same visit. If you are not sure what your child has had, or you have already arrived on the island without the vaccine, contact us today. Our English, German, and Hebrew-speaking team is available around the clock.
