Nelson schoolchildren have been offered new vaccination shots, after a storage fault affected the original batches of vaccines while they were being transported to schools.
Nelson Marlborough Medical Officer of Health Dr Ed Kiddle said vaccines given to 87 schoolchildren spent a short period of time in chilly bins where the temperature dropped below zero degrees Celsius during the journey to the schools.
The problem affected the HPV vaccine to prevent cervical cancer given to 15 girls in April, and vaccines given to 72 children in early May, including 20 HPV vaccinations and 52 booster vaccinations for diptheria, tetanus and whooping cough.
Vaccines should be stored at temperatures between 2C and 8C. Some are particularly sensitive to exposure to temperatures of 0C and below.
Kiddle said experts had advised the board that the effectiveness of the vaccines exposed to lower temperatures could have been affected.
"We have contacted parents and apologised for this incident and, based on external expert advice, recommended revaccination to ensure the children have received the appropriate levels of immunisation protection."
Kiddle said the school-based vaccination programme had been put on hold until solutions were found to prevent a repeat of the problem. These included using laptops and software to provide a more continuous temperature reading, and allowing data to be downloaded before vaccinations began.
The programme would recommence on May 21.
Kiddle said advice from the Immunisation Advisory Centre (IMAC) suggested that the subzero temperatures may have affected the vaccine, "so that we cannot be sure it will work, and hence we advise repeat vaccination".
"It is important to recognise that the children who received these immunisations were not exposed to any risks from receiving the vaccine that got too cold."
He said HPV was the most cold-sensitive of the vaccines involved, and expert advice indicated that there were no problems with a Year 8 child receiving an additional HPV shot.
For Tdap (tetanus, diphtheria and pertussis) shots, an extra dose could produce a greater localised reaction, with the injected arm being sorer than after the earlier injection, but no other problems were expected.
Dr Kiddle said national guidelines were followed for the transport of the vaccine, with ice being added to the chilly bins. "However, we suspect with cooler seasonal temperatures, it is likely the chilly bins were cold to start with, leading to this breach in vaccine temperature.
"A full review of the two incidents is being undertaken to ensure we learn as much as possible about improvements we can make to the programme."
A test of the data loggers on the chilly bins showed that the equipment was apparently not the cause of the temperature dip, Kiddle said.
Checks were being carried out for the outreach immunisation service for under-2-year-olds, but so far no temperature fluctuations had been found.
Over the past 2 years, over 5000 children have been immunised in the NMDHB School Based Vaccination Programme.
- The Nelson Mail
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