The outbreak of COVID-19 caused by SARS-CoV-2 rapidly spread worldwide and was declared a global pandemic in March 2020 by the World Health Organization [1]. As of December 2022, approximately 640 million people have been infected with SARS-CoV-2 and 6.6 million have died from this infection globally [2]. Clinical symptoms in people with COVID-19 include fever, cough, sore throat, fatigue, and headache, and patients in moderate-to-severe states develop dyspnea and pneumonia [3]. Several routes of person-to-person transmission of SARS-CoV-2 have been considered, and the risk of infection is thought to increase under crowded conditions of people in poorly ventilated environments [4]. The main routes of infection include droplet infection, wherein infectious viruses are contained in particles ≥5 μm in diameter, which are spread by an infected person through coughing or sneezing and adhere to the mucous membranes of the mouth, nose, and eyes of a non-infected person. SARS-CoV-2 can also be transmitted by inhalation of aerosols <5 μm containing viruses floating in the air [5]. Another is the contact transmission route, in which the virus enters the mucous membranes through contaminated hands by direct contact with droplets containing the virus or indirectly through contact with fomites to which the virus has adhered. For infection prevention and control measures against these virus transmission routes, wearing a mask to prevent the spread of droplets, ventilation of spaces to reduce aerosol transmission, and hand antisepsis are recommended [6].

Therefore, it is necessary to evaluate the environmental surface contamination of SARS-CoV-2 in various situations to recommend effective infection control measures for COVID-19. Although some reports are available on environmental surface contamination with SARS-CoV-2 in medical facilities and public spaces [[7], [8], [9], [10]], studies on environmental surface contamination at event venues, where the risk of infection increases because of the large number of people gathered, are limited. Therefore, we conducted environmental surveys of SARS-CoV-2 contamination at events in concert halls and banquet rooms, and evaluated the changes in environmental surface contamination with SARS-CoV-2 before and after events.