Study Shows Risks of Adverse Events Following COVID-19 Vaccines

A global study, known as the Global COVID Vaccine Safety (GCoVS) Project, was recently conducted by the Global Vaccine Data Network (GVDN) with funding from the CDC. [The study](https://www.sciencedirect.com/science/article/pii/S0264410X24001270), released on February 12th, 2024, observed over 99 million individuals vaccinated against COVID-19 across multiple countries and focused specifically on reviewing the overall occurrence rate of rare adverse events that occurred following the administration of the COVID-19 vaccines from December 2020 until August 2023. With such a large evaluated population size and number of geographical locations reviewed, the GCoVS is one of the largest epidemiology studies on vaccine injuries ever done. ## COVID-19 Vaccines and Adverse Events Reviewed The study reviewed the three main vaccines that were widely administered throughout the world and that had the highest number of doses administered, including the Pfizer/BioNTech BNT162b2, Moderna mRNA-1273, and Oxford/Astra Zeneca/Serum Institute of India ChAdOx1 vaccines. Using a common protocol, the observational study compared observed with expected rates of 13 selected adverse events across neurological, hematological, and cardiovascular conditions. The specific adverse events following vaccination that were evaluated in the study include neurological conditions like Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), Bell’s Palsy (BP), and transverse myelitis (TM). Other adverse events reviewed include cardiovascular conditions like myocarditis, pericarditis, and thrombosis, and hematologic conditions including cerebral venous sinus thrombosis (CVST), splanchnic vein thrombosis (SVT), pulmonary embolism (PEM), and immune thrombocytopenia purpura (ITP). ## Results of the Global Study The study found that there was an increased risk of developing specific adverse events (neurological conditions, cardiovascular conditions and hematologic conditions) following the administration of each of the three different COVID-19 vaccines when compared to historical occurrence rates of adverse events following other common vaccines. Some key observations for each of the vaccines are as follows: **Oxford/Astra Zeneca/Serum Institute of India ChAdOx1** - There was a statistically significant increase in GBS cases, TM cases and ADEM cases observed within 42 hours after a first dose of the Oxford/Astra Zeneca/Serum Institute of India ChAdOx1. - For cardiovascular conditions, the Oxford/Astra Zeneca/Serum Institute of India ChAdOx1 vaccine showed a statistically significant increase in observed cases of Myocarditis and Pericarditis by the last dose of the vaccine was administered. - The first dose of the Oxford/Astra Zeneca/Serum Institute of India ChAdOx1 vaccine showed a statistically significant increase in observed hematologic conditions, including immune thrombocytopenia purpura (ITP), thrombocytopenia (THR), pulmonary embolism (PEM), and cerebral venous sinus thrombosis (CVST). **Moderna mRNA-1273** - The Moderna mRNA-1273 vaccine showed a statistically significant increase in ADEM and Bell’s Palsy cases within 42 days after a first dose was administered. - For cardiovascular conditions, the Moderna mRNA-1273 vaccine showed a statistically significant increase in observed cases of Myocarditis and Pericarditis for the first dose of the vaccine. - The first dose of the Moderna mRNA-1273 vaccine showed a statistically significant increase in observed hematologic conditions, including thrombocytopenia (THR), pulmonary embolism (PEM), and splanchnic vein thrombosis (SVT). **Pfizer/BioNTech BNT162b2** - The Pfizer/BioNTech BNT162b2 vaccine showed a statistically significant increase in observed cases of Bell’s palsy within 42 hours of receiving a first dose. - For cardiovascular conditions, the Pfizer/BioNTech BNT162b2 vaccine showed a statistically significant increase in observed cases of Myocarditis and Pericarditis for the first dose of the vaccine. - The first dose of the Pfizer/BioNTech BNT162b2 vaccine showed a statistically significant increase in observed hematologic conditions, including immune thrombocytopenia purpura (ITP), thrombocytopenia (THR), pulmonary embolism (PEM), cerebral venous sinus thrombosis (CVST) and splanchnic vein thrombosis (SVT). ## In Conclusion This multi-country analysis confirmed the already established risks of developing adverse events following a COVID-19 vaccination, including myocarditis, pericarditis, Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), cerebral venous sinus thrombosis (CVST), and immune thrombocytopenia purpura (ITP). However, some vaccines, particularly the first dose of the vaccine, led to larger than expected occurrences of developing GBS, ADEM, and CVST when compared to historical occurrence rates of the adverse events following other commonly administered vaccines. Although the study is funded largely by the CDC, the results do not necessarily represent the official views or is an endorsement by the CDC, HHS or the U.S. Government. For more information regarding the study please review [the full article about the Global COVID Vaccine Safety (GCoVS) Project on science direct.](https://www.sciencedirect.com/science/article/pii/S0264410X24001270)