Friday November 23 2007
Researchers say children could be routinely vaccinated
”Scientists have developed a vaccine against a virus that kills hundreds of thousands of children across the world,” The Daily Telegraph reported today. A new vaccine against the rotavirus – the most common cause of sickness and diarrhoea in young children worldwide – has been developed, and, according to the newspaper is 90% effective in preventing the most severe cases.
Both the Daily Express and The Guardian report that “Tummy bug jabs ‘should be routine’” following the study in which more than 2,500 infants, aged between six and 14 weeks, were given the oral vaccine in addition to their usual immunisations.
This is a reliable study which suggests that rotavirus vaccination may have some future role in child health care. However, “tummy bugs” (gastroenteritis) are extremely common in young children and are usually a harmless hazard of being in close contact with other young children in nurseries and schools. The vast majority of children who contract rotavirus in the UK will suffer an illness of sickness, fever and diarrhoea, and with adequate hydration will recover fully within a few days, without any need for medical treatment. The frequency of this infection worldwide results in the high death rate with most of those fatal cases occurring in the third world.
There are many different strains of rotavirus, however, and this study has shown that they would not all be prevented by this vaccine. In addition, although it is the most common, rotavirus is not the only infectious cause of gastroenteritis in children and there are many other viral and bacterial causes which would also not be prevented by this vaccine. Therefore, even if young children were routinely vaccinated against rotavirus, it is important to realise that this would not bring an end to infections resulting in childhood sickness altogether.
Where did the story come from?
This research was carried out by Professor Timo Vesikari of the Vaccine Research Centre, University of Tampere, Finland, and colleagues from research and medical institutions in the Czech Republic, Germany, Spain and France, and GlaxoSmithKline in Belgium. Most of the research team were either employees of, or had had some previous involvement, with GlaxoSmithKline who are the manufacturers of the vaccine and also the funders the study. The study was published in the peer-reviewed medical journal The Lancet.
What kind of scientific study was this?
This was a double blind randomised controlled trial designed to test the efficacy of a rotavirus vaccine in preventing gastrointestinal illness in children during the first 2 years of life. The vaccine: Rotarix (RIX4414), was taken orally and was classified as live attenuated, which is an active but less virulent form of the virus.
The researchers enrolled 3,994 healthy infants, aged between six and 14 weeks, across six European countries (not including the UK). The infants were randomly allocated to receive either the vaccine in two oral doses (given one month apart at the same time as their routine immunisations), or an inactive placebo pill. Neither the study investigators nor the parents of the infants were aware if the baby had been given the vaccine or placebo.
The infants were followed from first vaccination for a further two years, across two rotavirus epidemic seasons (winter through to end of spring), to see if they developed any gastrointestinal illness (defined by this study as diarrhoea with three looser than normal stools in one day, with or without sickness), or any possible adverse effects from the vaccine.
The parents were contacted by the investigators once a fortnight during the study, and asked about any gastrointestinal symptoms, the course of the illness, and whether medical attention had been required. The parents were asked to record the features of the illness (e.g. number of loose stools, temperature, etc.) on a record card, which the researchers then used to give the illness a severity score on a 20-point scale. The parents were also asked to collect a stool sample that they tested for the presence of rotavirus.
The researchers compared the severity of rotavirus infection (caused by a naturally occurring form of the virus different from that in the vaccine) in those who had received the vaccine to those who had received placebo. Ninety-six per cent of the infants included in the study received both vaccinations and completed the full two years of follow up.
What were the results of the study?
There were 2,935 episodes of gastroenteritis (gut problems including diarrhoea and vomiting) during the course of the two years. Stool samples were available for the majority of the sickness episodes, from which the researchers found rotavirus to be the cause in 14% of episodes in the first season, and 13% of episodes in the second season. A variety of different rotavirus viral strains was found.
During the first rotavirus season (in the first year following vaccination) 7% of the children who had received the placebo contracted rotavirus gastroenteritis to any severe degree, a significantly higher figure than the children who had received the active rotavirus vaccination, of whom 1% became ill. Significantly fewer children who received the active vaccine had severe illness, required hospital admission, or needed any medical attention, compared to those who had received the placebo.
These findings remained significant across both infectious seasons, and if all cases over the two year follow up were analysed together. These results demonstrated the vaccine to work well, although better in the first year than the second. The vaccine worked more or less well against different rotavirus strains.
What interpretations did the researchers draw from these results?
The researchers concluded that their findings “confirm the high incidence of gastroenteritis during the first two years of life”. They say that the rotavirus vaccine, RIX4414, showed “a high and sustained efficacy against severe rotavirus infection and admission for rotavirus gastroenteritis”.
They suggest that two doses of the vaccine could be co-administered with other routine childhood immunisations to give a significant reduction in the rotavirus disease burden.
What does the NHS Knowledge Service make of this study?
This reliable study demonstrates a possible future role for the rotavirus vaccine in child health care. However there are several important things to bear in mind:
- Although the incidence of gastroenteritis was very high, the actual numbers of cases found to be due to rotavirus was relatively small, which demonstrates the large number of other viral and bacterial causes of childhood sickness besides rotavirus. Importantly, this highlights the fact that this vaccination would not end childhood sickness, but would just reduce the incidence of this type of virus.
- The fact that the children who had been vaccinated could still acquire rotavirus shows that it cannot prevent all cases of rotavirus gastroenteritis. As has been demonstrated by the stool sample testing in this study, there are many different strains of rotavirus and this vaccination is not effective in preventing all of them.
- As this study was only carried out in certain European countries, it may not be possible to generalise these results to other settings, in particular the developing world, where the burden of childhood gastroenteritis is the greatest.
- The vast majority of children who contract rotavirus will suffer an illness of sickness, fever and diarrhoea, and with adequate hydration will recover fully within a few days, without any need for medical treatment. It is the frequency of this infection worldwide which gives the overall high death rate, with most of those fatal cases occurring in the developing world.