Abstract
We appreciate the reviewer’s comment to our article on the correlation between the national BCG vaccination policy and coronavirus disease 2019 among Organisation for Economic Co-operation and Development countries as of April 20, 2020. In this letter, we further updated the data up to November 1, 2020, and found that the updated results also arrive at the similar conclusion as the accepted article.
Keywords: COVID-19, coronavirus infections, epidemiology, bacillus Calmette–Guerin vaccine, OECD, trained immunity
Dear editor:
Recently, we reported the possible relationships between the national Bacille Calmette–Guérin vaccination (BCGV) policy and coronavirus disease (COVID-19) infection using data from the Organisation for Economic Co-operation and Development (OECD) countries (Senoo et al., 2020). In the aforementioned articles, the incidence and mortality rates related to COVID-19 were collected as of April 20, 2020. Thus, in this letter, we updated and analyzed data as of November 1, 2020, and found that the results are similar to that in the accepted article.
The same 37 countries as in our previous study (OECD members with China and Taiwan) were included in this study. We excluded Iceland and Colombia, due to previous omission or joining after the former analysis. Updated data until November 1 of cumulative cases and deaths related to COVID-19 per million of population were collected from the report of the World Health Organization (WHO) (World Health Organization, 2020). Taiwan figures were collected from the Taiwan Centers for Disease Control website in the same manner as in a previous study (Taiwan Centers for Disease Control, 2020). The countries were categorized into the following three groups based on their implementation status of BCGV programs formulated from the World BCG Atlas (2017): Category 1, currently implemented (n = 15); Category 2, previously implemented (n = 17); and Category 3, never implemented (n = 5). We performed comparisons using the Kruskal–Wallis test, followed by the Mann–Whitney U test adjusted post-hoc Bonferroni correction. All statistical analyses were performed using Microsoft Excel 2016 and the modified version of R (The R Foundation for Statistical Computing, Vienna, Austria) called EZR Ver 1.53 (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which allows for a graphical user interface. p-Values < .05 were considered as being statistically significant.
Our results revealed a significant difference in both incidence (p = .0197) and mortality (p = .0281) rates of COVID-19 among three categories. In addition, the Bonferroni-corrected threshold between categories 1 and 3 showed significant differences in both incidence (p = .044) and mortality (p = .032) of COVID-19 (Figure 1).
Figure 1.
The relationship between COVID-19 and national BCG vaccination (BCGV) policy as of November 1, 2020. Cumulative cases and deaths related to COVID-19 per one million population are indicated on the left (cumulative cases) and right (cumulative deaths). Category 1, currently implemented BCGV countries; Category 2, previously implemented BCGV countries; Category 3, countries in which BCGV was never implemented. IQR, interquartile range.
We conclude that the analysis with updated data as of November 1 is similar to that in the previous study, meaning there exists a significant correlation between national BCGV policies and mortality and morbidity of COVID-19 among OECD countries, China, and Taiwan. Our finding is in line with those of other studies (Berg et al., 2020) and further supports the concept of trained immunity that confers “non- specific protective effects against infections other than the target diseases” (Netea et al., 2020).
Footnotes
Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article: TT reports personal fees from Medical Network Systems, MNES Inc., and Bionics co., Ltd, outside the submitted work. Other authors declare no conflicts of interest.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical approval and patient consent statements: Ethical approval by institutional review board is not necessary, because it did not include any patients.
Approval obtained for reproduction or modification of material published elsewhere: Not applicable.
ORCID iD
Kenzo Takahashi https://orcid.org/0000-0001-5672-3273
References
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