In many areas, Group B streptococcus (GBS) is the largest bacterial cause of newborn sepsis and meningitis, as well as a major source of sickness in pregnant women. Serotype-specific conjugate vaccines are now in the works. Researchers used an epidemiological study of health administrative data to estimate the burden of newborn GBS illness in Ontario, Canada and then coupled these estimates with literature on serotype distribution to estimate the burden of sickness that is likely to be vaccine-preventable. 

Between January 1, 2005, and December 31, 2015, 907 of 64320 health care interactions in Ontario in patients less than 1 year of age had codes directly indicating GBS as the etiology of the sickness, with 717 being under one month old. Furthermore, by applying epidemiological data to the remaining patients, researchers were able to predict an additional 2322 instances, 1822 of which were under one month of age. During the same time period, 579 confirmed newborn invasive GBS cases in individuals as young as one month old were reported to public health. The avoidable proportion varied greatly depending on serotype distribution, vaccination coverage, and early vs late-onset illnesses. Future vaccines might prevent up to 52% of early and late-onset illnesses with a vaccine that is 90% efficacious and 60% vaccination coverage.


In Ontario, GBS is underreported. Uncertainty regarding the possible impact of the vaccine suggests that more analysis and research, such as clinical validation trials and an economic evaluation of GBS immunization in Ontario, may be required to prepare for policy decisions.