Authors: Martha Powell, Future Science Group
Recently, researchers from the Wellcome Sanger Institute (Cambridge, UK), Simon Fraser University (Burnaby, Canada) and Imperial College London (London, UK) have optimized computer models for vaccines targeting Streptococcus pneumoniae, suggesting that vaccine programs need to be tailored to target specific subgroups of the population.
The study, published in Nature Microbiology, simulated pneumococcal vaccine performance over time to assess the potential risk of much more virulent strains replacing the vaccine-targeted serotypes.
The researchers started by optimizing a computer model for vaccine effectiveness on different serotype combinations. They then further analyzed the effectiveness of the vaccines using genomic data from Massachusetts (MA, USA) and the Maela refugee camp (Tak, Thailand).
There are approximately 100 serotypes of S. pneumoniae however, the current conjugate vaccine (PCV13), which is routinely given to children, only targets 13 serotypes.
“This approach to optimizing vaccines will help to address several problems, such as invasive disease among infants or adults and minimizing antibiotic resistance in the post-vaccine population. Such an approach also enables public health policy-makers to assess the likely effectiveness of an existing vaccine for a local population based on genomic surveillance data,” stated Author Caroline Colijn (Simon Fraser University and the Wellcome Sanger Institute).
The researchers also highlight that in Maela, infant infection with S. pneumoniae may be significantly reduced by removing some components from the conjugate vaccine. This could keep certain serotypes in circulation, thus preventing their replacement by more virulent strains.
“Our research shows that the best vaccine designs strongly depend on the bacterial strains present in the population, which vary considerably between countries. The best vaccine designs also depend on the age group being vaccinated. These ideas will be critical for applying lessons learned from introducing vaccines in high-income countries to combatting the disease where the burden is highest,” explained author Nicholas Croucher (Imperial College London).
Further analysis also allowed the researchers to determine that if adult vaccines were redesigned to complement infant vaccines, disease rates could be reduced by 50%.
“With the power of the latest DNA sequencing technology, we are heading towards a future where large-scale genomic surveillance of major bacterial pathogens is feasible. The approach we describe in this study will play an important role in accelerating future vaccine discovery and design to help reduce rates of disease,” commented author Jukka Corander (Wellcome Sanger Institute).
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Source: Colijn C, Corander J and Croucher NJ. Designing ecologically optimised pneumococcal vaccines using population genomics. Nat. Microbiol. doi:10.1038/s41564-019-0651-y (2020); www.imperial.ac.uk/news/195034/tailor-made-vaccines-could-almost-halve-rates/