New research from the University of Otago, Christchurch,
backs a recent Pharmac decision to provide broader
protection against a potentially fatal childhood
disease.
Late last year, in response to concerns
raised by child health experts, Pharmac amended the national
childhood immunisation schedule to include a 13-valent
pneumococcal vaccine (PVC-13) in response to rising case
numbers of Invasive Pneumococcal Disease (IPD).
Now, a
study comparing IPD incidence rates between Australia and
Aotearoa New Zealand backs Pharmac’s decision to upgrade
the vaccine from the existing 10-valent to a 13-valent
vaccine.
The study, published in The Lancet Western
Pacific medical journal, compared IPD case numbers in
both countries over a five-year period from
2017-2021.
It concludes that while the Indigenous
Australian population experienced the highest rates of the
disease (followed by Pasifika and New Zealand Māori), the
overall IPD rate in Aotearoa for pre-school children
increased during this time period, particularly cases of the
potentially life-threatening 19A IPD serotype.
While
ethnicity-adjusted IPD rates for children under two were
similar for both countries between 2017-2020, case numbers
in New Zealand rose sharply in 2021.The crude rate of IPD in
NZ children under two years of age was found to be more than
three times higher than in Australia, with 64.3 per cent of
isolates identified as serotype 19A. New Zealand’s
proportion of serotype 19A IPD cases increased from 11.5 per
cent to 29.5 per cent for children under five years old,
whereas Australian rates remained static at 5 per
cent.
Study co-author Professor Tony Walls, Paediatric
Infectious Diseases Specialist at the University of Otago,
Christchurch, says the results reinforce the timeliness of
Pharmac’s decision to switch to the PVC-13
vaccine.
“The World Health Organization recommends
that a switch in the vaccine used in any national PCV
programme should be considered if the epidemiology of IPD
changes significantly. This study, the first undertaken
comparing IPD rates in both countries, proves that
significant change was occurring in New Zealand, and that an
upgrade to the PVC-13 vaccine was urgently required,” says
Professor Walls.
“Pneumococcal disease is currently
the world’s number one vaccine-preventable cause of death
among infants and children younger than five years of age.
This decision will help arrest the concerning rise in IPD
case numbers in this country and better protect our young
children from the worrying and life-threatening risks the
disease poses.”
Australia’s national immunisation
schedule has funded a PVC13 vaccine since 2011. However,
while New Zealand’s immunisation schedule included a PVC13
vaccine from 2014-2017, it had reverted to a 10-valent
pneumococcal vaccine (PVC10) in 2017, due to low IPD case
numbers at the time, and in order to re-direct funding into
other vaccines.
Pneumococcal disease is caused by the
common bacteria Streptococcus pneumoniae. At the more
minor end, it can cause localised ear or sinus infections.
But IPD occurs if the bacteria get into the blood, resulting
in a severe form of pneumonia, bacteraemia (blood infection)
and meningitis, potentially affecting the heart muscle,
joints and abdomen. In 2022 there were 41 deaths due to IPD
in New Zealand. Also of concern, treatment can be
compromised due to rising rates of antibiotic
resistance.
Study co-author, University of Otago,
Christchurch Post-doctoral Research Fellow Nienke Hagedoorn,
says young Pasifika and Māori children in Aotearoa are
disproportionally affected, as are other vulnerable
groups.
“The risk of invasive pneumococcal disease
for Pasifika children and tamariki Māori is almost three
times higher than the risk for other ethnicities in New
Zealand. However, our study shows rates of serotype 19A are
also increasing among New Zealanders aged over 65 as
well,” says Hagedoorn.
“It’s important for
surveillance to also monitor serotype and IPD incidence in
older New Zealanders to inform ongoing policy on
pneumococcal vaccines. Their burden of disease should also
be considered as the influence of infant vaccinations can
also provide indirect immunity in older age
groups.”
Professor Walls warns the recent switch
from PVC10 to PVC13 may take a few years to significantly
reduce our burden of disease.
“Catch-up
immunisations for children under five are not part of the
PVC programme change, therefore those who received PVC10 may
not have adequate protection against serotype 19A,” he
says.
The study authors say improving immunisation
coverage nationwide, particularly in high-risk groups,
should be a key aspect of any plan to reduce the impact of
IPD due to stereotype
19A.
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