The aim of this paper is to identify bull and bear markets in the Bovespa index. For this, we estimated Markovian regime-switching models that incorporate duration dependence in which the transition probability also depends on the number of periods that the process has been in a particular state. The results indicated a regime with positive returns and low volatility and another with high volatility and negative returns. Moreover, the probability of switching out of the regime declines with the persistence of bull and bear markets. The smoothed probabilities evidenced the success of the methodology in identifying the main market downturns in Brazil. Finally, investment strategies were formulated based on the predicted probabilities of the models and these provided a higher average return and Sharpe ratio than the Bovespa index.

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SARS-CoV-2 genome surveillance is important for monitoring risk groups and health workers as well as data on new cases and mortality rate due to COVID-19. We characterized the circulation of SARS-CoV-2 variants from May 2021 to April 2022 in the state of Santa Catarina, southern Brazil, and evaluated the similarity between variants present in the population and healthcare workers (HCW). A total of 5291 sequenced genomes demonstrated the circulation of 55 strains and four variants of concern (Alpha, Delta, Gamma and Omicron—sublineages BA.1 and BA.2). The number of cases was relatively low in May 2021, but the number of deaths was higher with the Gamma variant. There was a significant increase in both numbers between December 2021 and February 2022, peaking in mid-January 2022, when the Omicron variant dominated. After May 2021, two distinct variant groups (Delta and Omicron) were observed, equally distributed among the five Santa Catarina mesoregions. Moreover, from November 2021 to February 2022, similar variant profiles between HCW and the general population were observed, and a quicker shift from Delta to Omicron in HCW than in the general population. This demonstrates the importance of HCW as a sentinel group for monitoring disease trends in the general population.