By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

SOURCE: Lui G, Lai CKC, Chen Z, et al. SARS-CoV-2 RNA detection on disposable wooden chopsticks, Hong Kong. Emerg Infect Dis 2020;26:2274-2276.

Although some may feel threatened by the possible presence of SARS-CoV-2 virus on their cereal box, Lui et al added a twist to the tale of surface contamination. Using real-time PCR (RT-PCR), they examined the risk of viral contamination of chopsticks used by patients with COVID-19 infection.

Five patients hospitalized for COVID-19 infection were recruited for this study, including one patient who remained asymptomatic, two whose symptoms had resolved, and two with active infection with moderate to severe COVID pneumonia. Patients received a set of plain, unvarnished, wooden chopsticks in a sealed plastic bag for meals. The chopsticks were collected, dipped in a buffered solution, and shaken for 30 seconds. SARS-CoV-2 RNA was detected using RT-PCR and compared with the results of serial sputum samples and nasopharyngeal (NP) and throat swabs.

Chopsticks from all five patients were positive at various points, similar to the results of sputum and NP/throat swabs, including those from the asymptomatic patient. This patient had been exposed to a known infected patient and, although she remained asymptomatic, she was hospitalized for isolation. On day 2 of her hospitalization (12 days after exposure), her throat and sputum samples tested positive for SARS-CoV-2, along with a pair of chopsticks. Although she was described as asymptomatic, a high-resolution chest CT showed patchy bilateral ground glass infiltrates and small areas of consolidation. Chopsticks from two other patients were positive for up to two to three days post-resolution of symptoms, although viral RNA could be detected in sputum specimens for up to eight days. Multiple sets of chopsticks were positive during the acute phase of illness in the remaining two patients (at days 5-7 in one patient with pneumonia and respiratory failure, and at days 7-8 in the final patient with fever and pneumonia).

This small study suggests salivary contamination of utensils with SARS-CoV-2 virus can occur. Sharing food and utensils, or using communal food bowls, which is common throughout Asia, probably is not a good idea if one is trying to avoid COVID-19. The Chinese government had been pushing to change the age-old practice of sharing morsels of food with children and partners using your own chopsticks as a demonstration of love and respect or even intimacy. Several restaurants have changed their practices by adding “serving chopsticks” to communal food bowls, but the practice remains limited, and many families have been resistant to this change.1


  1. Qin A. Coronavirus threatens China’s devotion to chopsticks and sharing food. The New York Times. May 25, 2020.