By the end of March 2021, 79 cases of unusual blood clots had been reported in those who have received the AstraZeneca vaccine in the United Kingdom, 19 of whom died (Holligan, 2021). However, the World Health Organization’s advisory vaccine safety panel clarified that the cases were very rare among 200 million people vaccinated with AstraZeneca globally. AstraZeneca said its studies found no causal link with blood clots; yet, the European Medicines Agency (EMA)’s team concluded that a causal link was not just possible, but probable (European Medicines Agency, 2021).     
 
As a consequence of the emergence of blood clot cases, vaccine hesitancy is surging in Europe as well as other parts of the world. Belgium restricted AstraZeneca to adults aged 56 and above, followed by Spain that restricted its administration to those between 60 and 64, Italy, France, Finland, and Germany also implemented similar approaches. At the individual level, more than 35% (N=1041) of Ireland’s population and 30% (N=2025) of the UK population admits their COVID-19 vaccine hesitancy (Murphy et al, 2021). While in the United States, about 31% of Americans would rather take a wait-and-see approach and 20% remain quite reluctant (Hamel et al., 2021).   
 
While COVID-19 vaccine hesitancy is becoming pervasive, it is even more difficult to achieve a herd community before winter arrives, when the situation may be exacerbated because of seasonal flu. Amid a pandemic that is devastating society and economies globally, it would be ideal to develop herd immunity through the deployment of effective vaccines rather than repeated waves of infection. However, many people feel the magnitude of benefits does not outweigh the possibility of risk. One way to combat vaccine hesitancy is to understand that the rapid development of the COVID-19 vaccines does not mean safety measures were overlooked. Several reasons have been summarized by John Hopkins Medicine. Importantly, communication between vaccinated individuals and prospective vaccine recipients about side effects and risks could be another strategic approach to tackle COVID-19 vaccination hesitancy.    
For further readings about COVID-19 vaccines, we recommend the perspective piece by Barney S. Graham which presents a neutral viewpoint with comprehensive information about rapid COVID-19 vaccine development. Another highly-recommended piece is by Dr. Anthony S. Fauci that explains the decades of robust basic science behind COVID-19 vaccines.