< Hygiene

Can the SARS-CoV-2 coronavirus be caught by going to the bathroom?

Text updated on 2020-09-28


Yes, the COVID-19 can become entangled in the bathroom, either by inhaling airborne viral particles or by touching contaminated surfaces.

Bathrooms are narrow, unventilated rooms. At least one case of contamination in an aircraft lavatory has been reported: the contaminated person had removed his mask in the lavatory. So keep your mask on in the bathroom!

Viral particles are present in aerosols. These aerosols may have been exhaled by previous persons or produced when the toilet is flushed. This is because the stools of people infected with the SARS-CoV-2 coronavirus contain many viral particles. This appears to be related to the fact that the ACE2 receptor, to which the coronavirus binds to enter cells, is present on the surface of the digestive tract. When you flush your toilet, some of the contents of the toilet bowl evaporate as droplets into the air (aerosolization). As a result, it is possible for the virus to be caught in the bathroom.

As a precaution: avoid sitting on the rim of the toilet, clean it regularly, use paper to touch door handles, toilet seat and toilet knobs, and close the toilet bowl tightly before flushing. Ventilate the bathrooms as often as possible. Caregivers of young children and the elderly should also be especially careful when handling diapers.


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Sources

Very detailed study of the 310 passengers on a Milan-South Korea flight: medical check-up in the airport before departure, only the asymptomatic persons took the plane (11 symptomatic persons did not take the plane), masks mandatory for the whole duration of the flight except for the bathrooms, 14-day quarantine on arrival in Korea and medical follow-up during the 14 days, tests COVID-19. A 28-year-old was infected when she took off her mask to go to the bathroom on the flight from Milan to South Korea. This person had been quarantined for 3 weeks alone at her home in Italy before the flight and had not used public transport to get to the airport. She had the first symptoms 8 days after the flight. On the plane, she used the same bathroom as a pre-symptomatic person (tested positive 2 days after the flight). The 18 cabin crew and medical personnel were not contaminated. They all wore masks.

Bae, S. H., Shin, H., Koo, H. Y., Lee, S. W., Yang, J. M., & Yon, D. K. Asymptomatic Transmission of SARS-CoV-2 on Evacuation Flight. Emerging infectious diseases, 26(11).

Near a patient with COVID-19 in Singapore, who was coughing and had a mild form of the disease, the SARS-CoV-2 virus was found in large quantities on the toilet bowl.

Ong, S. W. X., Tan, Y. K., Chia, P. Y., Lee, T. H., Ng, O. T., Wong, M. S. Y., & Marimuthu, K. (2020). Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient. Jama.

SARS-CoV-2 coronavirus was isolated from the feces of 3 patients with COVID-19. Viral particles thus isolated from 2 of the 3 patients proved to be infectious when tested on cells in culture.

Fei X, Jing S, Yonghao X, Fang L, Xiaofang H, Heying L, et al. Infectious SARS-CoV-2 in Feces of Patient with Severe COVID-19. Emer. Disgusting. Dis. 2020; 26(8).

DNA from the virus (500-100,000 copies per mL) was found by RT-PCR in the feces of 9 out of 17 infected individuals tested, 0-13 days after the first symptoms. These amounts are less than those observed in respiratory specimens.

Pan, Y., Zhang, D., Yang, P., Poon, L., & Wang, Q. (2020). Viral load of SARS-CoV-2 in clinical samples. The Lancet Infectious Diseases, 20(4), 411-412.

Viral particles were found by RT-PCR in the feces of 8 individuals (including 6 children) among 27 infected people tested. Four weeks after the onset of infection, one adult and two children (2 and 3 years old) still had viral particles in their stool, but no longer had any in their nose and throat swabs.

Ma, X., Su, L., Zhang, Y., Zhang, X., Gai, Z., & Zhang, Z. (2020). Do children need a longer time to shed SARS-CoV-2 in stool than adults?. Journal of Microbiology, Immunology and Infection.

The virus is present in the feces of COVID-19 patients.

Wu, Y., Guo, C., Tang, L., Hong, Z., Zhou, J., Dong, X., ... & Kuang, L. (2020). Prolonged presence of SARS-CoV-2 viral RNA in faecal samples. The Lancet Gastroenterology & Hepatology, 5(5), 434-435.

A meta-analysis of 60 studies, representing a total of 4,243 COVID-19 patients, indicated that 17% of patients had gastrointestinal symptoms and 48% of patients had stool with viral particles during infection. Of these positive cases, 70% of stool samples, collected after observing no sign of the virus in respiratory specimens, still contained the virus.

Cheung, K. S., Hung, I. F., Chan, P. P., Lung, K. C., Tso, E., Liu, R., ... & Yip, C. C. (2020). Gastrointestinal Manifestations of SARS-CoV-2 Infection and Virus Load in Fecal Samples from the Hong Kong Cohort and Systematic Review and Meta-analysis. Gastroenterology.

During the SARS outbreak in 2003, 99 people living in the same building were infected from a single apartment where an infected person had diarrhea. A thorough study shows that flushing triggers resulted in aerosolization of viral particles that were present in the stool. These particles then spread into the bathroom, passed through an exhaust fan and then entered the apartments on the upper floors.

Yu, I. T., Li, Y., Wong, T. W., Tam, W., Chan, A. T., Lee, J. H., ... & Ho, T. (2004). Evidence of airborne transmission of the severe acute respiratory syndrome virus. New England Journal of Medicine, 350(17), 1731-1739.

Even after flushing the toilet several times, some of the viral particles are still present in the water in the toilet bowl. In addition, when you flush the toilet, many droplets containing bacteria and viral particles are formed and can end up more than one meter from the toilet bowl.

Gerba, C. P., Wallis, C., & Melnick, J. L. (1975). Microbiological hazards of household toilets: droplet production and the fate of residual organisms. Appl. approx. Microbiol, 30(2), 229-237.

Mathematical modeling that suggests the existence of an alternative route of transmission of the virus that does not involve direct person-to-person contamination.

Ng, T. W., Danchin, A., & Turinici, G. (2020). A new transmission route for the propagation of the SARS-CoV-2 coronavirus. DOI: 10.21203/rs.3.rs-17870/v1 Preprint

In April 2020 in Shanghai, some people testified that in quarantine, back from abroad, before leaving their hotel room, they were asked to decontaminate their bathrooms by adding chlorine tablets in the toilet bowl, waiting 1 hour, and then flushing (Xinyu Jia, personal communication).


Presence of SARS-CoV-2 in wastewater.

Medema, G., Heijnen, L., Elsinga, G., Italiaander, R., & Brouwer, A. (2020). Presence of SARS-Coronavirus-2 in sewage. medRxiv.

ACE2 protein is abundant in the lungs and small intestine.

Hamming, I., Timens, W., Bulthuis, M. L. C., Lely, A. T., Navis, G. J., & van Goor, H. (2004). Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. The Journal of Pathology: A Journal of the Pathological Society of Great Britain and Ireland, 203(2), 631-637.

Indication that the SARS-CoV-2 virus induces lesions in the cells lining the small intestine and could thus lead to gastrointestinal symptoms.

Zhang H, Li HB, Lyu JR, Lei XM, Li W, Wu G, Lyu J, Dai ZM. (2020) Specific ACE2 Expression in Small Intestinal Enterocytes may Cause Gastrointestinal Symptoms and Injury after 2019-nCoV Infection . Int J Infect Dis. 2020 Apr 17. pii: S1201-9712(20)30238-1. doi: 10.1016/j.ijid.2020.04.027.

Further reading

How long is the coronavirus infectious?

What is the purpose of social distancing?

How do you wash your hands?

Is the SARS-CoV-2 coronavirus transmitted by aerosols?

What do the abbreviations COVID, SARS, CoV, RNA, etc. mean?

Why put on a mask?