Fewer vaccine doses can support pneumococcal immunity in babies

Fewer doses of a vaccine that protects against meningitis and pneumonia can still provide a level of immunity in babies, according to a new study. 

The research, led by Murdoch Children’s Research Institute, Pasteur Institute of Ho Chi Minh City and Menzies School of Health Research, has found that administering two doses of the pneumococcal conjugate vaccine (PCV), rather than three, in Vietnam could still provide protection against illnesses such as meningitis and pneumonia in babies.

The Vietnam Pneumococcal Trial II administered the PCV vaccine following the 1+1 vaccine schedule to babies at two months and 12 months of age. Results showed that the schedule reduced the amount of the pneumococcal bacterium in healthy children by up to two-thirds, which could help to stop the spread of disease and promote herd immunity.

The study, published in The Lancet Infectious Diseases, also found that administering just one dose of the vaccine at 12 months of age (known as a 0+1 vaccine schedule) could provide some herd protection. Researchers hope that this will help in situations where access to the vaccine is limited, such as in remote areas or during humanitarian crises. Currently, three doses of PCV are recommended for infants in Vietnam. 

The trial reported that the 1+1 vaccine schedule could be a suitable alternative in countries where the PCV vaccine is already being used or in countries that are in the middle of catch-up campaigns.

Menzies School of Research’s Beth Temple said, “Vaccination strategies that increase the accessibility and affordability of vaccines are urgently needed, and reduced vaccine schedules are one way to address this. 

“If fewer doses can be given, this helps reduce the cost, logistics and resources, and quantity needed to vaccinate a wider group of people. 

“The findings of the study provide substantial evidence to support the use of reduced-dose PCV schedules, and in turn can help protect more of our population against pneumococcal diseases.”

The 1+1 vaccine schedule could be a useful alternative in lower-to-middle-income countries as it’s still possible to achieve effective protection and reduce the transmission of disease in the community using fewer PCV vaccines.

Murdoch Children’s Professor Kim Mulholland said, “Severe pneumonia remains a major cause of child death in the poorer areas of the world. The children at highest risk are those living in poor, crowded housing, particularly those suffering from malnutrition.  

“Sadly, 23 years after PCVs were first introduced, these children are still the most likely to miss out on the vaccine. A fair world would have seen to it that these children were vaccinated first. Our studies in this area are designed to help authorities to protect all children, not just those from wealthy families.”

The Vietnam Pneumococcal Trial II has been made possible through financial support from the Bill & Melinda Gates Foundation.