Anticipating coincidental events It is possible to predict how often one would expect to see a coincidental association between a health event and immunisation. Using the expected incidence (number of cases per population to be vaccinated per time period) of the health event. For example, assume that one million children aged 6 weeks-20 years are immunised in a mass campaign and the background illness rate for this condition in this population is 3 per 100,000 per year. Then, 7.5 cases can be expected in the month after immunisation, simply by coincidence and 90 cases in the year. These cases will be temporally associated (similar timing) with, even though entirely unrelated to, immunisation. How is a new vaccine monitored for any unforeseen side effects? - The introduction of MeNZB ™ was supported by research data from a number of countries over many years. When most of the population is given a vaccine, events will occur following the receipt of the vaccine that are coincidental. The comprehensive Meningococcal B Vaccine (MeNZB™) Safety Monitoring Plan enables us to determine what is coincidental and what could be attributable to the vaccine.
- Vaccine safety is paramount and the NZ system is designed to detect any potential problems and investigate them in detail to establish causality.
- New Zealand instituted a gold standard in safety monitoring for a new vaccine. This included the Spontaneous Reporting Programme, where GPs voluntarily reported reactions they thought may be related to the vaccine as they do with all medicines and vaccines, and the Intensive Vaccine Monitoring Programme (IVMP), where a smaller group of general practices were intensively monitored and all reports of any reactions or illnesses were considered for up to six weeks after vaccination, whether or not they thought they were related to the vaccine.
- In the early stages there was also hospital based monitoring which meant that any child in the first area of roll out who went into hospital with any condition that could be remotely or possibly related to a vaccine was very carefully assessed. The Intensive Monitoring System did not pick up any increase in hospital visits for any monitored condition which included immunological and neurological conditions.
- There has been no increase in the incidence of monitored conditions since the programme started. These are conditions that occur every year in a small number of children. As expected, these conditions continued to present during the programme, both in children who received the vaccine and children who did not receive the vaccine. The rates of these conditions did not increase
Independent Safety Monitoring Board - The Independent Safety Monitoring Board (ISMB), a panel of international and New Zealand experts established by the Health Research Council of New Zealand (HRC), reviewed safety data throughout the programme until the end of June, 2006.
- The ISMB said it was satisfied that there was an "outstanding programme of sensitive and objective safety monitoring" throughout the rollout of the MeNZB™ vaccine.
- The ISMB also advised that it found no evidence of any significant adverse health event associated with the vaccine.
- With the end of the mass immunisation campaign, the monitoring of adverse events following MeNZB™ is now the same as for other vaccines.
Health professionals will continue to report any adverse events to the Centre for Adverse Reactions Monitoring (CARM) which monitors MeNZB™ and routine schedule vaccinations. - It was important to have a comprehensive safety surveillance system to identify serious adverse events that could be truly related to vaccination and to ensure that allegations relating to vaccine safety could be rapidly investigated.
Meningococcal B Vaccine (MeNZB™) Safety Monitoring Plan |
