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Virology, transmission, and pathogenesis of SARS-CoV-2

BMJ 2020; 371 doi: (Published 23 October 2020) Cite this as: BMJ 2020;371:m3862

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N-acetylcysteine as a possible adjuvant in the treatment of SARS-CoV-2

Dear Editor,

We refer to the article Virology, transmission and pathogenesis of SARS-CoV-2 (1) stating that a distinctive feature of Covid 19 is the presence of mucous plugs in the respiratory tract explaining the severity of this disease. In an earlier contribution in NTVG (2) we recommended treatment of these mucous plugs with mucolytic agent N-acetylcysteine reliving bronchiolar obstruction.

Furthermore the SARS-CoV-2 virus is, like the influenza virus, an RNA virus with a lipid double membrane envelope. Treatment strategies that favorably influence the course of influenza may also be effective in SARS CoV-2. In 1997 an Italian study was published on the effects of n-acetylcysteine on influenza at a dosage of 600mg twice daily. The outcome showed a significant decrease in the frequency of flu-like episodes, the severity and the duration of the illness. (3) NAC has been shown in vitro to inhibit the replication and expression of pro-inflammatory molecules in cells infected with the H5N1 influenza A virus. (4) NAC has been shown to have an antioxidant and immunomodulating effect in the treatment of influenza pneumonia (5), mitigating the chance of the cytokine storm responsible for the lung pathology.

We suggest considering N-acetylcysteine as an adjuvant to the standard treatment of SARS-CoV-2, also taking into account the favorable risk / benefit ratio and low costs of this drug.

Dr. D.J. Der Kinderen (
Dr. J.W. Koten (

1. Cevic, M, Kuppalli J, Kindrachuck J, Peiris M. Virology, transmission and pathogenesis of SARS-CoV-2. BMJ 2020;371:m3862
2. DerKinderen D, Koten JW. N-acetylcysteïne als adjuvant bij de behandeling van SARS-CoV-2.
3. The Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment. Eur Respir J 1997; 10: 1535-1541
4. Geiler J, Michaelis M, Naczk P, Leutz A, Langer K, et al. N-acetyl-L-cysteine (NAC) inhibits virus replication and expression of pro-inflammatory molecules in A549 cells infected with highly pathogenic H5N1 influenza A virus. Biochem Pharmacol 2009; 79: 413
5. Casanova T, Garigliany M. N-Acetylcysteine: An Old Drug With Variable Anti-Influenza Properties. Journal of Controversies in Biomedical Research 2016; 2: 1–8.

Competing interests: No competing interests

27 November 2020
Daan J. Der Kinderen
Jan W. Koten
De Bilt, The Netherlands