Gargling is a potential preventive strategy to reduce COVID-19 transmission

Coronavirus disease or COVID-19 is caused by a novel Coronavirus, which has been officially named as severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The disease is now six months old, but continues to be a global public health crisis and is showing no signs of stopping. The virus has rampaged across the world infecting more than16 million people; nearly 7 lakh people have died due to the infection.

Since COVID-19 is a new disease caused by a new pathogen, there are no proven treatment options or vaccine. Treatment is mainly supportive although potential therapies are being explored. Existing drugs like hydroxychloroquine, azithromycin are being repurposed for treatment.

Spread of COVID-19 is primarily person to person through respiratory droplets. Surface transmission from contaminated surfaces is another route of disease transmission, although it is now considered a less significant mode of transmission, as per the Centers for Disease Control and Prevention (CDC). Preventive measures such as use of face masks and hand hygiene offer the best protection against the virus.

Throat is a reservoir for the transmission of the virus as the virus mainly replicates here.1 A case series published in June in The Lancet Infectious Diseases has suggested that even asymptomatic and paucisymptomatic patients could be potential sources of infection because of the high viral load in the throat. 2

Since the SARS-CoV-2 has a predilection for the throat in the early stage of the disease, gargling may reduce the viral load in the throat of the infected patients, although it will not eliminate the virus. 3 Gargling, together with use of face masks and hand washing, therefore may be an important preventive strategy against common airborne (particles sized ≤5 µm) and droplet (particles sized >5 µm) infections. 4 A review of over 100 articles, published in the journal Function suggests that even a short-lived reduction in the levels of the shed virus may affect the transmission of disease to at-risk people or doctors in high-risk specialities like dentists, ear, nose, and throat surgeons and anesthetists. 5

Povidone-iodine (PVP-I) has been a widely used antiseptic for several decades owing to its universal spectrum of antimicrobial activity, which covers Gram-positive and Gram-negative bacteria, fungi, protozoa, bacterial spores and viruses. Other striking characteristics of PVP-I are a faster onset of action and more persistent effect and lack of selection of bacterial resistance. 6  

PVP-I, used as 0.23% mouthwash, has been shown to rapidly inactivate SARS-CoV and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in in vitro studies after a 15-second exposure.7 

There is evidence for its virucidal activity against SARS-CoV-2.

A study published July 8, 2020 in the journal Infectious Diseases and Therapy has demonstrated virucidal activity of PVP-I against SARS-CoV-2. The four topical and oral PVP-I products [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%)] tested against SARS-CoV-2 were found to kill the SARS-CoV-2 within 30 seconds of exposure demonstrating ≥99.99% virucidal activity ( ≥ 4 log10 reduction of viral titers) and rapid onset of action. Based on their findings, the study authors suggest that “the use of PVP-I products can augment health and hygiene measures to reduce the spread of COVID-19 in the community”. 7

In an in vitro conducted in the BSL-3 laboratory of the Tropical Infectious Diseases Research and Education Center (TIDREC), University of Malaya, Malaysia, Hassandarvish et al demonstrated the virucidal activity of PVP-I gargle against SARS-CoV-2 in just 15 seconds.8

A study evaluating the stability of SARS-CoV-2 in different environmental conditions observed that the virus remained viable for even a week on surfaces like stainless steel and plastic. However, the virus became untraceable following exposure time of ≥5 minutes to PVP-I (7.5%).7,8

PVP-I has the broadest spectrum of antimicrobial activity compared to other available antiseptics. Evidence of its rapid virucidal activity against SARS-CoV-2 suggests a role for PVP-I in reducing transmission of the infection and thereby containing the spread of the disease in the community. It has also shown significant activity against similar coronaviruses (SARS-CoV and MERS-CoV). PVP-I mouthwash is included in the WHO R&D blueprint for experimental therapies against COVID-19.9 Many patients with COVID-19 complain of sensation of “something stuck in their throat”. These patients can be given an oral antiseptic such as PVP-I rather than antibiotics, to reduce viral load in the throat.

References

  1. Meister TL, Brüggemann Y, Todt D. Virucidal efficacy of different oral rinses against SARS-CoV-2. J Infect Dis. 2020;jiaa471.
  2. Lescure FX, Bouadma L, Nguyen D, et al. Clinical and virological data of the first cases of COVID-19 in Europe: a case series. Lancet Infect Dis. 2020;20(6):697-70.
  3. Tsai C, Wu P. Possible beneficial role of throat gargling in the coronavirus disease pandemic. Public Health. 2020;185:45-6.
  4. Eggers M, Eickmann M, Zorn J. Rapid and effective virucidal activity of povidoneiodine products against Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Infect Dis Ther. 2015;4(4):491-501.
  5. O’Donnell VB, Thomas D, Stanton R, et al. Potential role of oral rinses targeting the viral lipid envelope in SARS-CoV-2 infection. Function. 2020;1(1):zqaa002.
  6. Lachapelle JM, Castel O, Casado AF, et al. Antiseptics in the era of bacterial resistance: a focus on povidone iodine. Clin Pract. 2013;10:579–592.
  7. Anderson DE, Sivalingam V, Kang AEZ. Povidone-iodine demonstrates rapid in vitro virucidal activity against SARS-CoV-2, the virus causing COVID-19 disease. Infect Dis Ther. 2020:1–7.
  8. Hassandarvish P, V Tiong, AB Sazaly, et al. Povidone iodine gargle and mouthwash. Br Dent J. 2020;228(12):900.
  9. Chin AWH, Chu JTS, Perera MRA, et al. Stability of SARS-CoV-2 in different environmental conditions. Lancet Microbe. 2020;1:e10.
  10. WHO R&D Blueprint COVID 19 Experimental Treatments: World Health Organisation. 2020. Available at: https://www.who.int/docs/default-source/coronaviruse/covid-classification-of-treatment-types-rev.pdf, Accessed 30.7.20.