Using Twitter for the identification of COVID-19 vaccine-associated haematological adverse events

Abstract

Although Operation Warp Speed (the US federal funding effort for vaccine development by pharmaceutical corporations) helped to facilitate the worldwide development of three US Food and Drug Administration (FDA) emergency-use approved COVID-19 vaccines in the USA in record time in 2020, it also resulted in rapid and large-scale vaccine dissemination before real-word safety studies outside of the original clinical trials could be done. Following widespread international use of several COVID-19 vaccines, rare, unexpected, and serious haematological complications began to be noticed by haematologists in the UK, Norway, Germany, Canada, and the USA in early 2021.