Longitudinal attenuation in political polarization: Evidence from COVID-19 vaccination adherence in Brazil

While political polarization in policy opinions, preferences, and observance is well established, little is known about whether and how such divisions evolve, and possibly attenuate, over time. Using the COVID-19 pandemic in Brazil as the backdrop, we examine the longitudinal evolution of a highly relevant and polarizing policy: adherence to the COVID-19 vaccination.

Studies 1 (N = 3346) and 2 (N = 10,214) use nationwide surveys to document initial differences and subsequent changes in vaccination adherence between conservatives ("Bolsonaristas") and non-conservatives ("non-Bolsonaristas"). Study 3 (N = 742) uses an original dataset to investigate belief changes among conservatives and their association with asymmetric changes in vaccination adherence.

Despite substantial differences at the early stages of rollout, the gap in vaccination adherence between conservatives and non-conservatives significantly decreased with the passage of time, driven essentially by a much faster uptake among the initially most skeptic-the conservatives. Study 3 demonstrates that the asymmetric changes in vaccination adherence were associated with meaningful belief changes among the conservatives, especially about the perceived effectiveness of the COVID-19 vaccines and the expected adherence of peers to the vaccination campaign.

Together, these studies show that, in a context where the superiority of the promoted policy becomes clear over time and individuals have the opportunity to revisit prior beliefs, even intense political polarization can be attenuated.