The COVID-19 outbreak has become the worst pandemic in at least a century. To fight this disease, a global effort led to the development of several vaccines at an unprecedented rate. There have been, however, several logistic issues with its deployment, from their production and transport, to the hesitancy of the population to be vaccinated. For different reasons, an important amount of individuals is reluctant to get the vaccine, something that hinders our ability to control and - eventually - eradicate the disease. In this work, we analyze the impact that this hesitancy might have in a context in which a more transmissible SARS-CoV-2 variant of concern spreads through a partially vaccinated population. We use age-stratified data from surveys on vaccination acceptance, together with age-contact matrices to inform an age-structured SIR model set in the US. Our results clearly show that higher vaccine hesitancy ratios led to larger outbreaks. A closer inspection of the stratified infection rates also reveals the important role played by the youngest groups. Our results could shed some light on the role that hesitancy will play in the near future and inform policy-makers and the general public of the importance of reducing it.
Impact of vaccine hesitancy on secondary COVID-19 outbreaks in the US