COVID-19 in patients treated with intravesical Bacillus Calmette Guerin

Dear Editor,

We would like to share ideas on the publication “Investigation of the frequency of COVID-19 in patients treated with intravesical BCG”. Karabay et al. concluded that “Intravesical BCG administration does not decrease the frequency of COVID-19 infection¹.” Indeed, effect of BCG on COVID-19 is an interesting issue. While some authors show that BCG might be useful, others present totally discordant ideas. A common consideration on any report of the BCG effect on COVID-19 is the confounding factor. Theoretically, by molecular mechanism via tertiary lymphoid structure (TLS) organogenesis^2,3, BCG might be useful. Trained immunity might occur after BCG vaccination. However, it is necessary to allow a period for immune training. From the observation by Karabay et al.¹, it might be interesting to assess time effect. Additionally, many confounding factors can affect the observed frequency of COVID-19⁴. In the report by Karabay et al.¹, the number of subjects are also few. A larger study might give different results.

• Funding: none.

REFERENCES

• ^1.
  Karabay O, Köse O, Tocoglu A, Uysal B, Dheir H, Yaylaci S, et al. Investigation of the frequency of COVID-19 in patients treated with intravesical BCG. Rev Assoc Med Bras (1992). 2020;66Suppl 2(Suppl 2):91-5. https://doi.org/10.1590/1806-9282.66.S2.91
  » https://doi.org/10.1590/1806-9282.66.S2.91
• ^2.
  O'Neill LAJ, Netea MG. BCG-induced trained immunity: can it offer protection against COVID-19? Nat Rev Immunol. 2020;20(6):335-7. https://doi.org/10.1038/s41577-020-0337-y
  » https://doi.org/10.1038/s41577-020-0337-y
• ^3.
  Koti M, Morales A, Graham CH, Siemens DR. BCG vaccine and COVID-19: implications for infection prophylaxis and cancer immunotherapy. J Immunother Cancer. 2020;8(2):e001119. https://doi.org/10.1136/jitc-2020-001119
  » https://doi.org/10.1136/jitc-2020-001119
• ^4.
  Wiwanitkit V. COVID-19 death and BCG vaccination. Tuberc Respir Dis (Seoul). 2021;84(1):84. https://doi.org/10.4046/trd.2020.0115
  » https://doi.org/10.4046/trd.2020.0115

Publication Dates

• Publication in this collection
  18 Oct 2021
• Date of issue
  Aug 2021

History

• Received
  11 June 2021
• Accepted
  14 July 2021