Comments on: The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality

Association Between Vitamin D and Novel SARS-CoV-2 Respiratory Dysfunction – A Scoping Review of Current Evidence and Its Implication for COVID-19 Pandemic

“…Both studies found a strong inverse correlation between mean vitamin D level in various European countries and COVID-19 mortality (Ilie et al, 2020;Singh et al, 2020) or COVID-19 incidence (Ilie et al, 2020) which was also supported by the results of the systematic review by Laird et al (2020). However, ecological approaches are at risk of potential confounding effects given the variation in measurements of a dependent variable such as number of detected COVID-19 cases; which for example may be significantly different from the number of true cases primarily due to differences in local screening policies (Garg et al, 2020;Gostic et al, 2020;Maruotti et al, 2020). Additionally, none of the abovementioned studies report the duration of time between the identification of first cases in a country and the reported death rates are unknown.…”

How strong is the epidemiological evidence to support any potential protective role for vitamin D levels on COVID-19 infections and mortality? - A time-series analysis of European Populations

“…The race to discover potential protective variables for COVID-19 incidence and mortality is ongoing with a range of things being proposed to be correlated with COVID-19 impact [2][3][4][5][6][7][8] [1], so more prone to biases due to relative disparate data sets [9]. Nevertheless, the potential protective impact of higher (or lower) vitamin D levels on COVID-19 incidence and adverse outcome possibility could be ascertained through controlled trials to ascertain its actual effect so as to limit any adverse impact due to prevailing vitamin D levels or alternatively that may be resulting from over or under supplementation of vitamin D with or without a medical prescription in the populations.…”

“…potentially playing a protective role based upon a one point cross-sectional analysis of the data by Ilie et al [5]. However, cautionary notes by us [7] and more recently by Maruotti et al [8] We hypothesized that if indeed vitamin D levels may have any potential protective role in COVID-19 as suggested previously, the COVID-19 impact on the select European countries with different vitamin D levels would consistently negatively covary/correlate rather than appearing as an effect of random fluctuation or seasonality just observable on 8 April 2020. The methodology previously employed failed to consistently support the potential protective role of vitamin D over the time period [5].…”

“…Based upon a correlation and regression analysis of a single day COVID-19 incidence and mortality data with serum vitamin D levels in populations[5], vitamin D had been proposed as a potential protective variable that may be explored further through dedicated studies. As indicated by us and others the oneday data analysis had weaknesses[7,8] and it would have been better had the analysis been not constrained by commonly used p-value cutoffs and improper model application on the biological data set, and preferably estimating the correlation post-peak of infections to reduce the effect of potential confounders of data reporting delay in infection and adverse outcome, and analyzing the correlation or regression at multiple points to arrive at potential dependable estimates.We now have COVID-19 data for the European countries for a larger time frame that by 26 July 2020 included a total of 1,829,634 cases and 179135 deaths accounting for the worldwide 11.11% cases and 27.45% deaths. The reanalysis of the data for an extended period indicates the potential problem of the analysis and model presented by Ilie et al[5] which was previously predicted/indicated by us and others[7,8].…”

“…As indicated by us and others the oneday data analysis had weaknesses[7,8] and it would have been better had the analysis been not constrained by commonly used p-value cutoffs and improper model application on the biological data set, and preferably estimating the correlation post-peak of infections to reduce the effect of potential confounders of data reporting delay in infection and adverse outcome, and analyzing the correlation or regression at multiple points to arrive at potential dependable estimates.We now have COVID-19 data for the European countries for a larger time frame that by 26 July 2020 included a total of 1,829,634 cases and 179135 deaths accounting for the worldwide 11.11% cases and 27.45% deaths. The reanalysis of the data for an extended period indicates the potential problem of the analysis and model presented by Ilie et al[5] which was previously predicted/indicated by us and others[7,8]. The simple linear regression modeling of the covariation of vitamin D levels with COVID-19 cases per million as suggested by the authors did not indicate a statistically significant correlation (p-value≥0.05) upto 8 Apr, which became statistically significant (at p-value cut off <0.05) by 12 April and stayed that way till 12 Jun then again become insignificant and remained so till the end of the analysis period, i.e., 26 July 2020.…”