It’s now or liver: time for a vaccine against hepatitis A?
A new study suggests this is a crucial question
Hepatitis A is not covered by SA’s standard vaccination programme for children, but has the time come for it to be included?
This is a question that was explored by experts at the University of Cape Town, who concluded there was “an urgent need for detailed evidence-based considerations to introduce a hepatitis A vaccine” into the programme.
Hepatitis A is, according to online resource Mayo Clinic, “a highly contagious liver infection caused by the hepatitis A virus. The virus is one of several types of hepatitis viruses that cause inflammation and affect your liver’s ability to function.”
Worldwide, there are currently 1.4 million new infections every year, and it spreads through the faecal-oral route (in other words, when viruses found in the stool of one person are swallowed by another). This is through an infectious person or by “ingestion of contaminated food or water”.
It may seem counterintuitive to the layperson, but the vaccine is only recommended in regions of intermediate endemicity and not where it is highly endemic.
As the World Health Organisation explains: “In countries where hepatitis A is highly endemic, exposure to hepatitis A virus is almost universal before the age of 10 years. In such countries, clinical hepatitis A is usually a minor public health problem, and large-scale immunisation efforts against this disease should not be undertaken.”
But in areas of intermediate endemicity, where transmission occurs primarily from person to person in the general community (often with periodic outbreaks), control of hepatitis A may be achieved through widespread vaccination programmes.
The risk factors are common in SA – “low socioeconomic status, larger household size and overcrowding, particularly in rural areas, and limited access to clean water sources and inadequate sanitation facilities” – but possibly due to improved conditions in some areas, the prevalence has been somewhat reduced here.
Lead researcher Annabel Enoch says: “Hepatitis A virus [HAV] is the most common cause of viral hepatitis worldwide. Hepatitis A vaccine is not included in the Expanded Programme on Immunisation in South Africa [EPI-SA], as the country is considered to be highly endemic for hepatitis A.”
The team thus wanted to study the seroprevalence (the level of a pathogen in a population, as measured in blood serum) of the infection, and chose the Western Cape as its research site, to see if it was still “highly endemic” in the country or had dropped to levels whereby immunisation would be indicated. The results have just had their research published in the South African Medical Journal.
The study involved blood samples from 482 children between the ages of one and seven. The blood specimens were, according to the study, “left over after laboratory testing obtained from referral hospitals between August and October 2015” while results from the National Health Laboratory from patients at Groote Schuur between 2009 and 2014 were also used.Furthermore, surveillance data from the National Institute for Communicable Diseases was also included to analyse trends over the same period.
The study showed a seroprevalence in the 1-7 age group as being at about 44% and also below 90% up to age 10, “indicating intermediate endemicity”.
The surveillance data showed that a substantial number of symptomatic hepatitis A infections occurred in the seven to 40-year age group, suggesting that “an increasing proportion of the population is susceptible to hepatitis A virus infection”.
This means that if we’re a country of intermediate endemicity and not high, we should be looking into vaccinating against it, which is why the researchers are calling for further studies to be done so that evidence-based decisions are made with regard to a vaccine going forward.