Background: Serial interval (SI) is one of the most important parameter for COVID-19 modelling purposes as it is related to the reproduction rate of the infection. The first meta-analysis of serial interval were performed with a range of uncertainty in the estimate. This meta-analysis aimed to reduce the uncertainty estimates by assessing publications over a longer period. Methods: A literature search was performed for articles published between 1st December 2019 and 15th February 2022. It retrieved 117 eligible studies containing some 80 for 90 serial interval estimates. A random effects model was used. Heterogeneity was checked. To detect a publication bias, a funnel plot was performed using an Egger’s test. Results: For alpha variant, the serial interval was estimated at 5.17 days (95% CI = 4.87 – 5.47) with a significant heterogeneity (I2 = 97.1%). The meta-analysis did not exhibit evident publication bias (Egger’s test = −0.55, p = 0.58). The meta-analysis allowed for reducing uncertainty in estimating the serial interval, although subgroup analysis did not reduce it sufficiently and showed that studies using a gamma distribution of serial intervals exhibited the highest estimate of 5.6 days. Compared to the other variants of concern, alpha serial interval estimate was bigger than delta, 4.07 days, and omicron, 3.06 days. Conclusion: The meta-analysis was carried out as a real-time monitoring of this parameter to make a choice and a rapid assessment of the control measures implemented, and the effectiveness of the vaccination campaign. The meta-analysis was unable to provide a suitable estimate of serial intervals for COVID-19 modelling purposes although its uncertainty was reduced. Furthermore, serial intervals estimate for alpha variant was close to earlier reports and lower than previous publications, respectively. Another limitation is, that meta-analysis of COVID pandemic studies in principle contains and produces itself a significant source of heterogeneity.

Background: During his life, Beethoven faced a lot of personal problems and diseases that could lead to a prolonged period of serious mental disorder. The aim of this work is to study the link between the distribution of pitch frequencies observed in 101 movements of 32 sonatas and four periods of his compositional style. Methods: The 32 sonatas for piano were chosen because they were composed during the three periods usually considered to reflect Beethoven’s career. A hierarchical generalized additive model was performed to regress the frequency of pitches with Musical Instrument Digital Interface (MIDI) pitches, periods of composition, degrees, rests, and length of the sonata’s movements. Results: The median frequency of pitches was higher during Beethoven’s time of mental distress. This period appeared as transitory between the bright Promethean period and the fullness of the final Ethereal period. This change in the expression of Beethoven’s creativity could well have played the role of a self-therapy. Conclusion: From this singular account of Beethoven’s history of mental problems and his way of dealing with them, it could be concluded that the stimulation of their musical creativity could be beneficial for psychiatrically patients with mental health issues. It also suggests that some mechanisms such as the application of hysteresis to cognitive function at a time of mental distress, may indicate new research avenues in the treatment of mental diseases.