Vaccine Safety Datalink
The Vaccine Safety Datalink (VSD) is a three-decade long research network established to conduct post-licensure observational studies of vaccine safety. The VSD is a collaboration of KPNW and twelve other integrated health systems and the Centers for Disease Control and Prevention. The VSD is led at CHR by Allison Naleway, PhD, Distinguished Investigator. The VSD utilizes standardized electronic health record-derived data on insurance enrollment, demographic characteristics, medical encounters from all settings, vaccination and prescribed medications to examine the safety of vaccines, including vaccines against COVID-19.
Near Real-Time Safety Surveillance
Since 2006, the Vaccine Safety Datalink has conducted weekly vaccine surveillance known as Rapid Cycle Analysis. When the first COVID-19 vaccine was administered in December 2020, weekly monitoring of this new vaccine started immediately. VSD investigators developed an internal dashboard to facilitate visualization and rapid reviews of large weekly automated vaccine safety surveillance data on COVID-19 vaccines. This report includes interim findings on risk of adverse events after receipt of mRNA COVID-19 vaccines through June 2021.
Another VSD study identified and tracked cases and incidence of Guillain-Barre Syndrome (GBS) following COVID-19 vaccination and assessed the risk of GBS after vaccination for Ad.26.COV2.S (Janssen) and mRNA vaccines. GBS has occurred in the past following other vaccinations so it was important to study it in this context.
The VSD updated previously reported comparisons of myocarditis and pericarditis incidence during a risk interval after mRNA vaccination versus a later comparison interval and presented new head-to-head comparisons assessing whether risk differs between the two mRNA vaccines.
COVID-19 Vaccine Safety in Pregnancy
The Vaccine Safety Datalink is one of four systems used by the CDC to monitor the safety of COVID-19 vaccines after pregnancy.
A retrospective cohort study of live births from eight Vaccine Safety Datalink health care organizations evaluated risks for preterm birth (<37 weeks' gestation) and small-for-gestational-age at birth (birthweight <10th percentile for gestational age) after COVID-19 vaccination (receipt of ≥1 COVID-19 vaccine doses) during pregnancy. Results consistently showed no increased risk when stratified by mRNA COVID-19 vaccine dose, or by second or third trimester vaccination, compared with risk among unvaccinated pregnant women.
In a study of COVID-19 vaccines and acute adverse events, the VSD evaluated the incidences of 25 medically attended events (known reactogenic adverse events and clinically serious outcomes) among vaccinated women compared with unvaccinated matched controls. COVID-19 vaccines were not associated with an increased risk of the clinically serious acute adverse events that were evaluated.
The VSD conducted case-control surveillance of COVID-19 vaccination during pregnancy and spontaneous abortion. Among women with spontaneous abortions, the odds of COVID-19 vaccine exposure were not increased in the prior 28 days compared with women with ongoing pregnancies. Another study aimed to understand how time since vaccine roll-out or other methodologic factors could affect results.
COVID-19 Vaccination in Children
The VSD studied the safety of COVID-19 vaccination among children ages 5-11, analyzing data from three safety monitoring systems to study v-safe, the voluntary smartphone-based system that monitors reactions and health effects; the Vaccine Adverse Events Reporting System (VAERS), the national spontaneous reporting system comanaged by the CDC and Food and Drug Administration; and the Vaccine Safety Datalink.
Data Mining Safety Assessments
Complementing its real-time surveillance for pre-specified health outcomes using pre-specified risk intervals, the VSD conducts tree-based data-mining to look for clustering of a broad range of health outcomes after COVID-19 vaccination. In one study, the VSD used this untargeted, hypothesis-generating approach to assess the safety of first booster doses of Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273) and Janssen (Ad26.COV2.S) COVID-19 vaccines.
COVID-19 Vaccination and Mortality
To assess mortality not associated with COVID-19 after vaccination against the disease in a general population setting, members from seven VSD sites, including the Center for Health Research, conducted a cohort study among approximately 11 million people enrolled in VSD sites. After standardizing mortality rates by age and sex, the study found that COVID-19 vaccine recipients had lower non-COVID-19 mortality than did unvaccinated individuals.