Cases of vaccine-resistant pneumonia are increasing despite the jab being included in routine childhood immunisations.

A national study by the University of NSW and other research centres found the majority of 779 children admitted to hospital with pneumonia had been fully vaccinated.

Data from children hospitalised was collected from 11 tertiary paediatric hospitals across Australia between 2015 and 2018.

UNSW’s Dr Nusrat Homaira said the current vaccine should provide optimal protection against 13 different variations of bacterial pneumonia.

But two serotypes, a group of similar microorganisms like bacteria or viruses, called serotypes 3 and 19A are bypassing the effects of the vaccine.

There are two possible explanations for why the vaccine has failed to prevent children from developing serious pneumonia illnesses.

The study suggested the vaccine does not produce a strong enough immune response due to biochemical properties of serotype 3.

The second possible reason could be that the time frame in which vaccines are administered does not cause lasting immunity.

The data used was from children who were administered vaccines at two months, four months and six months of age.

Most countries administer vaccines at four months, six months and 12 months.

“Having the final dose at 12 months provides more lasting protection than having the last dose at six months,” Dr Homaira said.

Australia has moved its dose schedule to reflect other countries since 2018, while new formulations of bacterial pneumonia vaccines are becoming available.

Researchers are also calling for routine testing of lung fluid to better monitor the development of pneumonia illnesses and newer formulation of vaccines for better protection.

– AAP