Plans to vaccinate everyone aged under 20 against meningococcal disease depend on the success of a trial starting in Auckland shortly. ANDREW LAXON reports.

In a few months volunteers should start walking through the doors of the University of Auckland medical school, rolling up their sleeves and giving blood samples.


The 90 human guinea pigs will then be given an injection against meningococcal meningitis, the disease that has killed 184 New Zealanders, many of them children, in the past decade.


Thirty will get a new vaccine, developed specifically for New Zealand. Thirty will get a variation on this vaccine, and the rest will get the Norwegian vaccine, which served as model for our version.


The 18-to-50-year-olds taking part in this clinical trial - possibly Auckland Hospital doctors and nurses if other Aucklanders are reluctant to come forward by May - will take away a diary to record any reactions, such as a sore arm or a temperature.


Six weeks later, they will be back for another dose and another blood test to see if the vaccine is working. In six more weeks, they will return for their final dose and blood test (all sent to Government laboratories for evaluation, with checks by international experts).


Then scientists will start to know whether the $100 million experiment to stop New Zealand's worst infectious disease is working.


For Professor Diana Lennon, the childhood infectious diseases specialist running the trial, an even more important test will come in the next phase.


If the vaccine works on adults, she hopes to start trials among 100 to 150 older schoolchildren this year, before moving on to the same numbers of toddlers and babies. She describes this as the absolute "stop-go" point of the trial - children under 5 with poorly developed immune systems are the disease's biggest victims.


If the second phase works, the vaccine will gradually be introduced into high-risk areas such as South Auckland. If it brings the disease rate down with no severe side-effects, the vaccine will be used to immunise a million New Zealanders under the age of 20.


After that, meningococcal B vaccine could become part of the child immunisation schedule given at six weeks, three months and five months (with shots against hepatitis B, diphtheria and measles, mumps and rubella) within the next five years.


All this involves a lot of "ifs", but the scale of meningococcal disease has given the search for a vaccine a sense of urgency. Since 1991 New Zealand has suffered 184 deaths and the epidemic is expected to last another decade, with 4000 more cases and 200 more deaths.


One in every 100 Maori and Pacific Island children under 5 can expect to catch meningococcal disease, which is strongly linked to poverty.


Although no one knows exactly what causes it to spread, Auckland researchers have shown that the risk here increases with household overcrowding. Overseas research has suggested a link with passive smoking, but not enough to account for all the cases.