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Among healthcare workers, nurses are at exceptionally considerable risk for contracting COVID-19. Regardless of professionals' level of education, Brazilian nursing is one of the healthcare occupations shouldering the highest levels of responsibility and workload. Social support networks to health and nursing can be a strategy to reduce workload and stress and may contribute to implementing the activities and protecting workers' health. This study aimed to map and analyze social support networks at workplaces as informed by frontline nursing professionals working in healthcare units in the Brazilian cities of Rio de Janeiro and Fortaleza, capitals of the States of Rio de Janeiro and Ceará, respectively. This observational and cross-sectional study used an online data collection instrument based on social network analysis methodology. We recruited 163 participants in two reference services for health professionals suspected or with COVID-19 symptoms. The research question was: "Which category or categories of health professionals have supported you or other colleagues the most in the event of diagnosis or suspicion of COVID-19 among nursing categories? Data were organized by nursing category and city and analyzed through social network analysis using Ucinet©, generating graphs and centrality metrics. Results point to the central relevance of nursing categories in the workplace social support in the pandemic, followed by other health professional categories., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 David et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The SARS-CoV-2 pandemic has revived the debate about the routes of virus transmission and their likelihoods. It is of utmost importance to assess the risks of contamination of susceptible people by infectious individuals and to evaluate the level of SARS-CoV-2 and other respiratory viruses transmission in the community. Most countries have imposed non-pharmaceutical measures to contain SARS-CoV-2 transmission, including physical distancing and mask wearing. Here we evaluated the spreading of viruses in open air using harmless Escherichia coli bacteriophages as a surrogate. Phages were sprayed towards Petri dishes seeded with bacteria at different lengths and angles. Our results showed that the transmission rate decreased exponentially with distance. The highest recorded transmission rate was [Formula: see text] PFU/plate when phages were sprayed from a 1 m distance, suggesting that the probability of transmission of a single virus at a 1 m distance is 1:100,000., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: It is widely assumed that all mutant microorganisms present in a culture are able to grow and form colonies, provided that they express the features required for selection. Unlike wild-type Escherichia coli, PHO-constitutive mutants overexpress alkaline phosphatase and hence can hydrolyze glycerol-2-phosphate (G2P) to glycerol and form colonies on plates having G2P as the sole carbon source. These mutations mostly occur in the pst operon. However, the frequency of PHO-constitutive colonies on the G2P selective plate is exceptionally low., Results: We show that the rate in which spontaneous PHO-constitutive mutations emerge is about 8.0 × 10 -6 /generation, a relatively high rate, but the growth of most existing mutants is inhibited by their neighboring wild-type cells. This inhibition is elicited only by non-mutant viable bacteria that can take up and metabolize glycerol formed by the mutants. Evidence indicates that the few mutants that do form colonies derive from microclusters of mutants on the selective plate. A mathematical model that describes the fate of the wild-type and mutant populations under these circumstances supports these results., Conclusion: This scenario in which neither the wild-type nor the majority of the mutants are able to grow resembles an unavoidable "tragedy of the commons" case which results in the collapse of the majority of the population. Cooperation between rare adjacent mutants enables them to overcome the competition and eventually form mutant colonies. The inhibition of PHO-constitutive mutants provides an example of mutant frequency masked by orders of magnitude due to a competition between mutants and their ancestral wild-type cells. Similar "tragedy of the commons-like" cases may occur in other settings and should be taken into consideration while estimating true mutant frequencies and mutation rates.