Gargling: Breaking the chain of infection : Dr KK Aggarwal

The main route of transmission is human to human through direct inhalation of respiratory droplets released when an infected person coughs or sneezes.³ The virus also enters the body through the mouth, which functions as a reservoir for the virus. A study published in Nature confirmed active viral replication in the throat with very high pharyngeal (throat) shedding of the virus during the first week of the illness, when the infection is still mild. Infectious viral particles were isolated from throat swabs. The peak levels were reached before the fifth day and were more than 1,000 times higher than with SARS, making COVID-19 a much more contagious disease.⁴

Povidone-iodine (PVP-I) has been shown to rapidly inactivate the SARS and MERS coronaviruses. It has also demonstrated rapid and effective virucidal activity against SARS-CoV-2 virus in in vitro studies.

PVP-I gargle and mouthwash exhibited virucidal activity against SARS-CoV-2 in just 15 seconds. Anderson et al showed ≥ 99.99% virucidal activity with all the PVP-I formulations tested [antiseptic solution (PVP-I 10%), skin cleanser (PVP-I 7.5%), gargle and mouth wash (PVP-I 1%) and throat spray (PVP-I 0.45%)] against SARS-CoV-2, corresponding to ≥ 4 log10 reduction of virus titre, within 30 sec of contact. ⁵

The universal spectrum of antimicrobial activity, faster onset of action, more persistent effect and lack of selection of bacterial resistance are features which give PVP-I an edge over other available antiseptics.

The chain of infection involves six inter-linked components: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry and a susceptible host. Breaking the chain at any one point or more can prevent the spread of infection.

The SARS-CoV-2 virus can replicate in the throat even before it reaches the lungs. Hence, it can spread very easily among people, especially those who are in close contact. Reducing the amount of virus at this initial stage of infection might positively influence the course of the disease. 

Gargling with an antiseptic such as PVP-I may help to break the chain of infection by reducing the viral load in the throat and decreasing the amount of virus released in droplets which is why it should also be recommended as a preventive measure alongside hand hygiene, masking and physical distancing. Gargling helps by removing the oral/pharyngeal protease, which helps the virus to replicate. 

References

1. WHO Weekly Epidemiological Update, Coronavirus disease 2019 (COVID-19), 12 October 2020. Available at: https://www.who.int/docs/default-source/coronaviruse/situation-reports/20201012-weekly-epi-update-9.pdf.

1. Hu B, et al. Characteristics of SARS-CoV-2 and COVID-19. Nat Rev Microbiol. 2020;1-14.

1. Esakandari H, et al. A comprehensive review of COVID-19 characteristics. Biol Proced Online. 2020;22:19.

1. Wölfel R, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020 May;581(7809):465-9.

1. Anderson DE, et al. Povidone-iodine demonstrates rapid in vitro virucidal activity against SARS-CoV-2, the virus causing COVID-19 disease. Infect Dis Ther. 2020:1-7.

1. Tsai C, et al. Possible beneficial role of throat gargling in the coronavirus disease pandemic. Public Health. 2020;185:45-6.

1. Bidra AS, et al. Rapid in-vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using povidone-iodine oral antiseptic rinse. J Prosthodont. 2020;29(6):529-33.

1. Lachapelle JM, Castel O, Casado AF, Leroy B, Micali G, Tennstedt D, et al: Antiseptics in the era of bacterial resistance: a focus on povidone iodine. Clin Pract 2013;10:579-92.

1. Charité – Universitätsmedizin Berlin. “Coronavirus: Virological findings from patients treated in a Munich hospital.” Science Daily, 3 April 2020.

1. Herrera D, et al. Is the oral cavity relevant in SARS-CoV-2 pandemic? Clin Oral Investig. 2020;24(8):2925-30.

1. Kitamura H, et al. Can we prevent influenza-like illnesses by gargling? Intern Med. 2007;46(18):1623-4.

Author : Dr KK Aggarwal , President CMAAO, HCFI and Past National President IMA

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