What is Hepatitis A?
Hepatitis A is a viral infection of the liver. Hepatitis A virus (HAV) infection most commonly causes fever, jaundice, nausea, vomiting, diarrhea, fatigue and itchiness. A smaller percentage of infected individuals can develop rash and joint pain (11% and 14%, respectively). Bone marrow suppression, brain inflammation (encephalitis), eye nerve inflammation (optic neuritis), blood vessel inflammation (vasculitis), are rare complications, but have been documented. Less than 1% of HAV infected patients die from complications. Between July 2016 and January 2024, 424 HAV deaths were reported in the United States. Fortunately, unlike Hepatitis B infections, HAV infections are not known to cause chronic liver disease or liver cancer.
How long do HAV infections last?
Symptoms can last varying lengths of time depending on the age of the patient. Children under 6 years of age experience symptoms only 30% of the time. Duration of illness for these young children is typically 2 weeks or less. Older children and adults experience symptoms much more frequently and for a longer period of time:
- 40% require hospitalization
- 70% develop jaundice
- 80% liver enlargement
- Symptom duration up to 3-6 months
How is HAV spread?
Like hepatitis B and C viruses, HAV can be spread by contact with blood or sexual body fluids. Unlike those other hepatitis viruses, HAV is also spread by the fecal-oral route. HAV is shed from an infected person’s stool. If hands are not adequately washed with soap and water after post-defecation wiping, HAV can be spread by those contaminated hands. Parents, daycare workers and other infant/toddler caregivers are at risk for getting and/or spreading HAV if they don’t appropriately wash their hands after changing dirty diapers of infected children.
HAV can contaminate food and water and typically enters the body through the mouth. That entry could be directly on/in contaminated food or water. Infection also occurs by contaminated hands touching the mouth, or the mouth directly contacting contaminated surfaces or objects. Not surprisingly, young children who are curious, mobile, and mouthy (i.e. constantly putting their hands and other objects in their mouths, or putting their mouths directly on objects) are among those at highest risk for getting infected when exposed.
Don’t sanitation systems in the United States minimize HAV infection risk?
Yes, in contrast to less developed countries, our food and water quality protocols limit “endemic” spread of HAV. One of the challenges with preventing HAV outbreaks is that we import a lot of food from other countries. Examples of outbreaks due to imported food include the following:
2013 – contaminated pomegranate seeds imported from Turkey
2016 – contaminated raw scallops imported from the Philippines
2019 – contaminated fresh blackberries imported from Mexico
2022 – contaminated fresh organic strawberries imported from Mexico
2023 – contaminated frozen organic strawberries imported from Mexico
How long does it take to develop symptoms after HAV exposure?
The incubation period (time between exposure and developing symptoms) for HAV can be anywhere from 2 weeks to nearly 2 months (average is 4 weeks). Infected individuals are most contagious in the 1-2 weeks before jaundice develops (if it develops at all). This large window of time leads to many challenges for public health/infection control measures, among which are:
(1) Increased difficulty tracking when, where, or how someone was exposed.
(2) Spread of HAV unknowingly by infected individuals who have not yet developed symptoms, or who may not develop symptoms at all.
Is there a treatment for HAV?
No, there are no specific anti-viral medications that can treat an already infected individual. All medical professionals can do is provide patients with guidance on how to manage the symptoms while waiting for the body to fight off the infection and the liver to heal. Symptomatic treatment may include fever reducers, pain relievers, and anti-nausea medication. IV fluids are sometimes needed in cases of dehydration.
HAV immune globulin (i.e. antibody) can be administered by intramuscular injection within 2 weeks of exposure for those who have not been vaccinated. Unfortunately, that 2 week window often passes before an individual might learn they were exposed. Additionally, HAV immune globulin protects for only 1-2 months and does not provide the long-term immunity vaccination does.
What type of vaccine do we have against HAV?
The HAV vaccine is an inactivated vaccine. There is no live virus in the vaccine (similar to the polio shot), and therefore cannot cause HAV infection or liver inflammation.
How effective is the HAV vaccine and how long has it been available?
Approximately 95% of healthy individuals develop adequate protection within 1 month of the first dose. More than 99% are protected within one month of the second dose.
HAV vaccine was first licensed in the United States in 1995 and was originally only recommended for those at increased risk for disease (e.g. those traveling internationally to countries where infections were more prevalent, drug users, men who have sex with men, and children living in communities with high rates of disease). In 1999, the recommendation expanded to all children in 11 Western states where infection rates were much higher. Recommendations were expanded to all children, and all high-risk adults in all 50 states in 2006. From 1996 to 2011, rates of reported HAV infections in the United States decreased over 95%. Since 2011, outbreaks have largely occurred in the unvaccinated adult population, further underscoring the effectiveness and benefit of the vaccine to all the children who have received it routinely for the past 20 years.
When is the HAV vaccine administered?
The two-dose series is recommended starting at 12 months old. We administer the vaccine at the 12 month and 18 month old check-ups. Note: to optimize the immune response, the two doses should not be administered any closer than six months apart. Be careful to schedule your child’s 18 month check-up at least six months after the 12 month check-up.
What are possible side effects of the HAV vaccine?
Swelling, redness and soreness around the injection site are the most common side effects and last a couple days or less if they occur. Less than 10% of recipients develop temporary headache, decreased or loss of appetite, or nausea. Ongoing monitoring has not shown any severe adverse effects from the HAV vaccine.
Ok, there’s a safe and effective vaccine, but why should children in the United States be vaccinated if exposure risks are relatively low and symptoms are typically self-resolving?
- Low exposure risk does not mean no exposure risk. HAV infections result from everyday experiences. As mentioned above, the continued importation of contaminated, commonly consumed foods like fruits (remember, this included fresh, frozen and organic products) leaves all unvaccinated individuals susceptible.
- Young children (younger than 6) are unlikely to develop symptoms, and those who do usually recover in two weeks or less. But this makes them even more likely to unknowingly spread the infection to their older siblings, caregivers or other close contacts who could be more sickened by infection. Being handsy, mouthy, and contagious without symptoms are important ingredients in the recipe of HAV outbreaks.
- Older children are similarly unlikely to develop liver failure or die due to HAV, but 70+% develop symptoms, which can last up to six months, and result in significant disruption of quality of life due to missed school days, missed work for parents, and missed life experiences such as athletics and social events.
- There’s no anti-viral treatment for HAV, so prevention is key.
Resources
2024. “Hepatitis A”, Red Book: 2024–2027 Report of the Committee on Infectious Diseases, Committee on Infectious Diseases, American Academy of Pediatrics, David W. Kimberlin, MD, FAAP, Ritu Banerjee, MD, PhD, FAAP, Elizabeth D. Barnett, MD, FAAP, Ruth Lynfield, MD, FAAP, Mark H. Sawyer, MD, FAAP
https://www.uptodate.com/contents/overview-of-hepatitis-a-virus-infection-in-children
Hofmeister MG, Ly KN, Yin S, Spradling PR. Evolving Characteristics of Decedents With Hepatitis A Listed as a Cause of Death, United States, 2011-2021. J Viral Hepat. 2024 Dec;31(12):783-794. doi: 10.1111/jvh.14002. Epub 2024 Sep 3. PMID: 39225298; PMCID: PMC11809443.
https://www.cdc.gov/hepatitis-a/outbreaks/index.html
https://www.chop.edu/vaccine-education-center/vaccine-details/hepatitis-a-vaccine