EULALEE THOMPSON
For some paediatricians, the advent of a vaccine against the common
childhood condition, gastro-enteritis, can be equated to the invention, many years ago, of the oral polio vaccine.
"IT'S A great advance. I wasn't around when the OPV (oral polio vaccine) came around in 1954, but this must have been how the doctors then felt," said Professor Celia Christie, professor in paediatrics, University of the West Indies. "I mean, I may be out of a job in another five to 10 years because the vaccine will be available, but I am still feeling great about it."
Professor Christie was the principal investigator of the local clinical trials in Merck & Co. international clinical trials for the rotavirus vaccine, RotaTeq. There were 356 sites from 11 countries involved in this trial and Jamaica's site (at the University of the West Indies) had the largest enrolment.
"Our trials went well. We had 1,805 children enrolled ... The data went to Merck and they analysed them in aggregate," she said. Professor Christie and her team will be carrying out an analysis of the local data on the Jamaican babies in the study over the next year or so. This vaccine, RotaTeq, has since been approved by the U.S. Food and Drug Administration (FDA).
VACCINE LAUNCHED
But, it was another rotavirus vaccine, Rotarix, by another pharmaceutical company, GlaxoSmithKline, that was launched here last week. It is available in the private sector as the Ministry of Health has not added this vaccine to its immunisation schedule for babies. Rotarix is a live vaccine, based on a single attenuated human rotavirus strain (G1).
The rationale is to mimic the natural infection caused by the wild-type virus without causing disease (gastro-enteritis). Rotarix should protect babies from diarrhoea and vomiting (the prominent symptoms of gastro-enteritis) by delivering protection when it is needed.
Rotarix is given in the first six months of life, with the first dose given between six and 14 weeks of age, followed by a second dose between 14 and 24 weeks of age with a minimum interval of four weeks between the two doses.
FIVE LIVE ROTAVIRUS STRAINS
RotaTeq (from Merck), on the other hand, contains not one, but five live rotavirus strains (G1, G2, G3, G4, and P1), which studies indicate account for more than 80 per cent of cases of human rotavirus disease (New England Journal of Medicine, Jan. 5. 2006). Inactive ingredients in RotaTeq include sucrose, sodium citrate, sodium phosphate monobasic monohydrate, sodium hydroxide, polysorbate 80 and also foetal bovine serum.
RotaTeq is given by mouth in three doses. The first dose is given when the child is six to 12 weeks old, the second dose is given four to 10 weeks later and the third dose is given four to 10 weeks after the second dose. The last (third) dose should be given to the child by age 32 weeks.
ISSUES TO CONSIDER
Professor Christie said that even with the wonderful news of the availability of the rotavirus gastro-enteritis vaccines, from the Jamaican perspective there are some issues to consider in the future.
"We are hoping that (eventually) we will find a way to give the (oral polio vaccine and the rotavirus vaccine) at the same time. The two live oral vaccines will be given in a staggered manner and this means that parents will have to make two or three extra visits for (their babies') vaccines. We might lose some people in the process," she said.
Also of concern in developing countries, Professor Christie said, is that since immunisation starts at six weeks, it is too early to make any diagnosis of disease in the babies such as HIV, malnutrition and so on. The vaccine is known to work in the well population and it is not yet clear if it will work effectively in the unwell population.
Another major concern is the price of the vaccine. Since it is not currently available in the public sector, Professor Christie fears that the sickest children may not have access to the product because their parents cannot afford it.
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