  The outbreak of COVID-19 had a huge global impact, and non-scientific beliefs
and political polarization have significantly influenced the population's
behavior. In this context, COVID vaccines were made available in an
unprecedented time, but a high level of hesitance has been observed that can
undermine community immunization. Traditionally, anti-vaccination attitudes are
more related to conspiratorial thinking rather than political bias. In Brazil,
a country with an exemplar tradition in large-scale vaccination programs, all
COVID-related topics have also been discussed under a strong political bias. In
this paper, we use a multidimensional analysis framework to understand if
anti/pro-vaccination stances expressed by Brazilians in social media are
influenced by political polarization. The analysis framework incorporates
techniques to automatically infer from users their political orientation, topic
modeling to discover their concerns, network analysis to characterize their
social behavior, and the characterization of information sources and external
influence. Our main findings confirm that anti/pro stances are biased by
political polarization, right and left, respectively. While a significant
proportion of pro-vaxxers display haste for an immunization program and
criticize the government's actions, the anti-vaxxers distrust a vaccine
developed in a record time. Anti-vaccination stance is also related to
prejudice against China (anti-sinovaxxers), revealing conspiratorial theories
related to communism. All groups display an "echo chamber behavior, revealing
they are not open to distinct views.
