This retrospective cohort study gathered data from electronic health records of nearly one million children enrolled in the Kaiser Permanente Southern California (KPSC) integrated healthcare system. Researchers sought to describe trends in routine childhood vaccination occurring in the pre-pandemic, stay-at-home, and reopening periods of 2020 in a large cohort of Southern California children, and compared these findings to the corresponding periods in 2019.
During the early stages of the COVID-19 pandemic, there was a drastic decline in well-child visits and therefore decreased vaccine administration to children, thus increasing the risk of vaccine-preventable diseases (VPDs). Both weekly vaccine doses administered as well as measles-containing vaccine administration were significantly lower at the beginning of the stay-at-home order in March 2020 compared to 2019.
Decline in vaccination was less severe in children aged <2 years, and vaccination in this age group was quicker to increase back to near pre-pandemic levels. However, vaccination remained lower in older age groups as well as in non-Hispanic Black children. This is likely in part due to focused efforts of healthcare providers to specifically vaccinate the <2 year age group, given the large number of vaccines given during a short time period to these children.
These efforts can be expanded to children of all ages and racial groups to increase vaccine uptake and reduce racial disparities. This study is strengthened by its large and diverse sample of children across multiple medical centers in Southern California, but may not reflect trends among children with poorer access to health care and insurance coverage.
Overall, these findings raise concern that outbreaks of VPDs may be on the horizon, and efforts should be taken to ensure all children are up-to-date on their routine immunizations.