Upper respiratory tract infections (URTIs) are one of the most frequently encountered illnesses in clinical practice. They figure among the 10 most common clinician- and patient-reported reasons for primary care visits.¹ Though URTIs can be bacterial in origin, most of them are caused by viruses such as the rhinovirus, human parainfluenza virus, adenovirus, metapneumovirus, human respiratory syncytial virus and human coronaviruses. The various URTIs such as common cold, pharyngitis, rhinitis, sinusitis often have similar clinical presentations and it is also clinically difficult to differentiate between the different viral etiologies.²

Covid-19 is the latest addition to the differential diagnosis of respiratory infections as it can present as a mild illness of the upper respiratory tract. As per the WHO’s latest Covid-19 Weekly Epidemiological Update (dated Aug. 31, 2022), currently, the BA.5 sublineage of the Omicron variant of concern is the dominant circulating strains globally and accounts for nearly 80% Covid-19 cases in many parts of the world. BA.5 is also presumed to be the most contagious strain of SARS-CoV-2 as of now. Sore throat, hoarse voice, headache, fatigue, blocked/runny nose, shortness of breath, fever, cough with/without sputum, sneezing are now the most common presenting symptoms of Covid-19, which overlap with the symptoms of other URTIs. Loss of taste and/or smell, which were considered almost pathognomonic of Covid-19 during the Delta wave now occur less often. Because of the ongoing pandemic, all patients with URTIs must therefore be considered as potential Covid-19 infections and should be isolated and tested for SARS-CoV-2.

Besides the overlapping symptoms, Covid-19 and other common respiratory viruses causing URTIs also share common modes of transmission. The most common route of entry for these viruses is the respiratory tract. They spread via droplets, aerosols produced during coughing, sneezing, or just talking, singing, or breathing or direct contact with contaminated surfaces or objects (fomites) in the immediate vicinity of the patient.

Upper respiratory infections start with the attachment and colonization of respiratory pathogens to the oropharyngeal mucosa. ⁴ The replication and shedding of virus in the early stage of Covid-19 occurs mainly in the throat. ⁵ Corroborating this, a Nature study demonstrated active viral replication in the throat with very high pharyngeal virus shedding within the first week of the illness in hospitalized Covid-19 patients. The peak levels were reached before the fifth day of the illness.³

Gargling, a traditional home remedy for sore throats, might therefore be potentially useful in reducing transmission of virus. It has been shown to be effective in preventing URTIs among healthy people.⁶ Because of the tropism of SARS-CoV-2 for throat in early infection, gargling may be a beneficial practice in the Covid-19 pandemic as well.⁷

Gargling with an oral antiseptic such as povidone-iodine (PVP-I) has been advocated as a preventive measure against respiratory infections. Gargling with PVP-I at least 4 times daily reduced the incidence of acute exacerbations of chronic respiratory infections.⁸

Compared to the other commonly used antiseptics such as chlorhexidine, octenidine, the widely used PVP-I has “the broadest spectrum of antimicrobial action” with activity against Gram‐positive and Gram‐negative bacteria, bacterial spores, fungi, protozoa and several viruses.” PVP-I also has the “highest virucidal activity profile among several antiseptics.”⁴  It has demonstrated activity against several respiratory viruses including the severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses and also SARS-CoV-2. The faster onset of action, lack of reported resistance and excellent safety profile are the other beneficial features of PVP-I.

PVP-I demonstrated ≥99.99% in vitro virucidal activity against SARS-CoV-2 corresponding to ≥ 4 log10 reduction of the viral load within 30 sec of contact with all the four PVP-I products tested including gargle and mouth wash (1%).⁹ Thrice-daily gargling with PVP-I for 30 sec led to 100% viral clearance in just 4 days, whereas the viral clearance after gargling with essential oils was 80%, 20% with tap water and 0% in the control group with no intervention. ¹⁰ The potent virucidal activity against SARS-CoV-2 has also been demonstrated as early as 15 seconds following use of PVP-I gargle and mouthwash.^11,12

Early clearance of the virus is crucial as URTIs including Covid-19 are highly infectious at the early stage of the infection. While the need of the hour certainly is inactivation of SARS-CoV-2, gargling with an antiseptic such as PVP-I complementary to the routinely advocated preventive measures such as masking, hand hygiene, physical distancing, cough hygiene may protect against Covid-19 as well as non-Covid respiratory infections. Although gargling does not eradicate the virus from the throat, it may reduce severity of infection by reducing the viral load and viral shedding thereby decreasing the risk of community transmission.⁷

References

1. Finley CR, et al. What are the most common conditions in primary care? Systematic review. Can Fam Physician. 2018 ;64(11):832-40.
2. Teng CL, et al. The management of upper respiratory tract infections. Med J Malaysia. 2001;56(2):260-6; quiz 26.
3. Wölfel R, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465-9.
4. Kanagalingam J, et al. Practical use of povidone-iodine antiseptic in the maintenance of oral health and in the prevention and treatment of common oropharyngeal infections. Int J Clin Pract. 2015;69(11):1247-56.
5. O’Donnell VB, et al. Potential role of oral rinses targeting the viral lipid envelope in SARS-CoV-2 infection. Function. 2020;1(1):zqaa002.
6. Satomura K, et al. Prevention of upper respiratory tract infections by gargling: a randomized trial. Am J Prev Med. 2005;29(4):302-7.
7. Tsai C, et al. Possible beneficial role of throat gargling in the coronavirus disease pandemic. Public Health. 2020;185:45-6.
8. Nagatake T, et al. Prevention of respiratory infections by povidone-iodine gargle. Dermatology. 2002;204 Suppl 1:32-6.
9. 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.
10. Mohamed NA, et al. Early viral clearance among covid-19 patients when gargling with povidone-iodine and essential oils – a clinical trial. MedRxiv. Sept 9, 2020.
11. Hassandarvish P, et al. In vitro virucidal activity of povidone iodine gargle and mouthwash against SARS-CoV-2: implications for dental practice. Br Dent J. 2020 10;1-4.
12. 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.