This winter we will be going on a ten day cruise in the Caribbean. We will also be staying at a luxury resort in Mexico for a few days after the cruise. Could you please give me more information on the hepatitis shots that I see advertised on television? We oppose vaccination in general, so we have already made the decision to avoid routine vaccines here in Canada.
Hepatitis A is a virus found world-wide, but it is more prevalent in some parts of the world. As a result, travelers to these areas are at an increased risk of being infected. When one travels to countries where there is poor sanitation, one is at a particular risk of getting infected by this virus. However, studies have shown that even when staying at luxury hotels and traveling with credible cruise lines, the risk of getting hepatitis A still remains high enough to recommend the use of a vaccine prior to visiting endemic areas.
The virus spreads via feces - the so called oral-fecal route. Specifically, hepatitis A is resistant to acid which allows for passage through the stomach. Food borne hepatitis A transmission can occur from food that is contaminated during preparation by an infected food handler. Foods which are particularly infectious are sandwiches and salads.
When a person gets infected, the incubation period is on average 28 days. The onset of the illness, particularly in adults, manifests itself with fevers, loss of appetite, tiredness, nausea, abdominal pain, dark urine, and jaundice.
In children younger than 6 years, more than 90% of hepatitis A infections are asymptomatic. Infants also have no symptoms after they are infected, but they can spread the virus to adults. The spread occurs most often via feces when diapers are changed. Thus, daycare workers have to be extra diligent in washing their hands after changing diapers.
Once a person has been infected with hepatitis A, they have immunity for life. In some unusual cases, they can experience relapses or fulminant liver disease. They cannot infect others once they have recovered, but they will never be able to donate blood.
Currently, there are two vaccines available specifically against hepatitis A. These vaccines have an effectiveness rate of 97%. The earliest age that the vaccine can be used is 12 months. It is given intramuscularly and can be combined with most other vaccines. Protection starts at about one month after the vaccine is given, and a second dose is recommended within 6 to 12 months. The vaccine is mercury free with the most common side effect being pain and swelling at the site of the injection. It is thought to be safe for use during pregnancy and lactation.
Given it takes four weeks for the vaccine to take effect, it is ideal to get it done well before traveling to an area where hepatitis A is more prevalent. However, for families who tend to leave things until the last minute, there is also the option of combining hepatitis A immunoglobulin with the hepatitis A vaccine. This combination is usually given at the same time and at a different injection site (thus, requiring two needles instead of one).
If a person is exposed to hepatitis A but was never vaccinated, a dose of hepatitis A immune globulin is also an alternative to consider. However, the protective effect lasts for only 3 months. The use of the immune globulin is an option for children under the age of 12 months (too young to receive the vaccine) who will travel to high risk areas with their families. This may apply to immigrant families where young babies travel to countries where the parents were born, visiting families in their country of origin and where hepatitis A is endemic.
The duration of protection against hepatitis A after vaccination is close to 20 years. So, children who were given the vaccine will probably need a new vaccine 20 years later, when they take their own children on a trip to countries where the virus is more prevalent.
In Canada, most children who attend school would have received a vaccine against hepatitis B, but not hepatitis A, sometime in grade 5. It is important to know your child's immunization history as there is also a vaccine, Twinrix, which combines hepatitis A and B in one single vaccine. Families who want their children protected against both of these types of hepatitis at an earlier age, using this specific vaccine, should decline the duplicated vaccinations given for hepatitis B in grade 5.
Current recommendations, published in July 2007 by the American Academy of Pediatrics (AAP), call for the use of hepatitis A vaccine starting at age one. The AAP also considers male adolescents who engage in anal sex with other males at high risk, and recommends that these individuals receive the hepatitis A vaccine. The same is true for users of injectable and non-injectable illicit drugs.
The Canadian Pediatric Society has no position statement at this time regarding universal use of hepatitis A vaccination. The Public Health Agency of Canada communicates their advice on immunizations through the National Advisory Committee on Immunization (NACI). For more information on travel health, see their web site at www.phac-aspc.gc.ca.
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