Vaccine hesitancy is a state of indecision and uncertainty about vaccination before a decision is made to act (or not act). It represents a time of vulnerability and opportunity. Multiple surveys that were conducted to examine the sentiments concerning coronavirus disease 19 (Covid-19) vaccination have exposed new levels of volatility around vaccine hesitancy, particularly when the hesitancy is powered by digital media platforms. Spikes in vaccine hesitancy often coincide with new information, new policies, or newly reported vaccine risks. Some of the variability is due to factors such as a decline in the public’s trust of experts, preferences for alternative health, political polarization, and belief-based extremism. In this review, we use the examples of hesitancy regarding the measles–mumps–rubella (MMR), human papillomavirus (HPV), and Covid-19 vaccines to look at the multifaceted issues that fuel vaccine hesitancy. Each of these examples is part of a larger, complex story.
Timing is everything when it comes to vaccine acceptance or hesitancy, and the mutable nature of vaccine hesitancy calls for new modes of analysis to characterize not only the temporal features of hesitancy but also the spatial (e.g., regional) features and the many behavioral manifestations and their effects on vaccine uptake. Such real-time data also allow investigation into contextual events that can help us understand the drivers of hesitancy. Vaccine acceptance can be increased, but responsiveness to emerging concerns is key. Given that physicians and other health care providers are still among the most trusted figures when it comes to health care advice, local information about the nature and scope of vaccine hesitancy in their communities may help them anticipate and support important conversations in the clinic.