Chinese researchers have developed the world’s first ever vaccine against a strain of enterovirus that can cause hand, foot and mouth disease, a condition commonly affecting small children that can lead to deadly infection of the brain and spinal cord membranes.
Hand, foot and mouth disease causes fever and blisters around the hands, feet and mouth. It is transmitted by contact with faecal matter, blisters or saliva of an infected person.
Hand, foot and mouth disease can be caused by a range of different germs, including a group called enteroviruses. One kind of enterovirus, called enterovirus 71 (EV71) is of particular concern as it can cause severe disease in children, sometimes leading to potentially fatal meningitis and encephalitis.
According to a paper published in the journal The Lancet, the new vaccine protects against enterovirus 71 (EV71).
The study involved 10,245 children aged between six and 35 months who lived in four different places in China. Half were given two doses of the vaccine and half were given a placebo.
“During active surveillance, vaccine efficacy was 90% against EV71-associated hand, foot and mouth disease and 80·4% against EV71-associated disease,” the researchers said in their paper.
The vaccine also demonstrated 100% efficacy against EV71-associated hospitalisation, “suggesting that it could have a significant impact on public health by preventing severe outcomes of EV71 infection,” say the authors.
However, the researchers said that their vaccine did not protect against coxsackievirus A (CA) 16, a disease commonly associated with enterovirus71 that can also cause hand, foot and mouth disease.
They also cautioned that during the 12 month study of the children, “only a small proportion of cases of hand, foot and mouth were confirmed as associated with EV71, indicating that EV71 might not be the dominant pathogen in this hand, foot and mouth season.”
“Despite its high efficacy for preventing EV71-associated hand, foot and mouth disease, the EV71 vaccine might have little part in reducing the overall incidence of hand, foot and mouth, even by universal mass immunisation of children,” the researchers said.
Robert Booy, Professor and Head of Clinical Research at the National Centre for Immunisation Research and Surveillance at the University of Sydney said the new finding was very exciting and addressed the prevention of EV71 infection and its potentially life-threatening manifestations like encephalitis.
“This virus has caused a fairly severe outbreak in the Sydney metropolitan region over the past six months, with many children admitted to hospital, some with life-threatening disease. A very high level of protection is demonstrated by this study in the short term (about a year follow up) and it will be important to determine longer-term protection,” said Professor Booy, who was not involved in the study.
Professor Booy said the vaccine appears to be well tolerated.
“Southeast Asia and China have seen a number of serious outbreaks of EV71 in young children over the past decade or so. This new vaccine may soon be ready for use in places where outbreaks of EV71 are just starting. Whether it will become a routine - universal vaccine depends on research into its cost-effectiveness.
Major step forward
Dr David Hawkes, Research Officer in the Peptide Neurobiology Laboratory at the Florey Institute of Neuroscience and Mental Health, said the new vaccine was of special interest to Australia because of a recent increase in a genotype of EV71 (C4) that is associated with more severe neurological conditions.
"It is this strain that is targeted by the vaccine,” said Dr Hawkes, who was not involved in the study.
“It is important to note that while this trial is a major step forward, there are still a number of significant questions which need to be addressed, such as whether it gives cross-protection against other genotypes of EV71, how long protection lasts (this study only examined 1 year post vaccination), and whether it is cost effective in a country like Australia (where the last outbreak was in 1999 and affect 14 people).”
Dr Hawkes said that in the first five months of 2013, five cases of acute flaccid paralysis associated with EV71 (C4) have been reported and there are currently no effective antiviral treatments against EV71.
“In addition, 15 cases of encephalitis, three cases of viral meningitis and one of spinal myelitis have also been reported,” he said.