To estimate the time-dependent transmission potential of primary pneumonic plague (PPP), we analyzed historical records from six outbreaks. Based on contact investigation information (source of infection information) of three outbreaks, we generalized the probability density function of the serial interval with a Gamma distribution using maximum likelihood estimations. Furthermore, we used a likelihood-based approach to estimate effective reproduction numbers at time t, R_t, incorporating records from the remaining three outbreaks by assuming independence within unknown contact networks. According to our estimates, the R_t of PPP during the initial phases of each epidemic were roughly in the order of 1.3 (95% confidence interval (CI): 0.0-4.3) in Oakland, 1.4 (0.0-4.6) in Rangoon and 6.5 (0.0-16.0) in Ecuador. The expected values of R_t were shown to slightly exceed unity, even in latter stages. While declining trends in R_t were observed in Oakland and Ecuador, no such trend was observed in Rangoon. The findings suggest that the three outbreaks investigated could have been accompanied by demographic stochasticity. The statistical usefulness of the transformation procedure, even with a small number of recorded cases available, was demonstrated, and the expected responses to bioterrorism using Yersinia pestis were discussed.

Methods: This prospective cohort study analyzed patients with osteoporotic vertebral fractures admitted to the hospital between March 2018 and October 2019. Logistic regression analysis was performed to explore the predictors of vertebral collapse at >4 weeks after admission. Model 1 used basic medical information and physical functions at admission; model 2 used basic medical information and physical function and activity at >4 weeks after admission. Results: In the model 1 results of logistic regression analysis, cardiovascular disease (odds ratio [OR], 12.27; 95% confidence interval [CI], 1.28–117.91) was extracted as a factor affecting vertebral collapse at ≥4 weeks after admission. In the model 2 results of logistic regression analysis, cardiovascular disease (OR, 34.57; 95% CI, 2.53–471.74), movement control during one leg standing at 4 weeks (OR, 7.25; 95% CI, 1.36–38.71), and Pain Catastrophizing Scale score at 4 weeks (OR, 1.11; 95% CI, 1.01–1.21) were extracted as factors affecting vertebral collapse at ≥4 weeks after admission. Conclusions Our results indicate that physical functions and comorbidity affect collapse at ≥4 weeks after admission in patients with osteoporotic vertebral fractures.