[Survey of the effect of the SARS-CoV-2 outbreak on the job training members with high exercise intensity: Analysis of the factors causing infection spread and the effectiveness of the prevention measures].

Abstract

Objectives: Immediately before the state of emergency was declared, there was an outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among special training participants with severe physical stress. For promoting the optimization of infection prevention measures by identifying acts and situations with high risk of infection, we conducted a survey and analysis to understand the detailed process of infection spread in these cases.

Methods: A structured interview was conducted for the special training participants on their health status, changes in symptoms, training methods, and behavior history in their private lives. Additionally, a patrol of the training facility was carried out to understand the training environment, and antibody tests were conducted on the close contacts for more accurately grasping the spread of infection, by identifying subclinical infected persons.

Results: Within 10 days of COVID-19 onset in the first patient, 15 of the 19 original training participants developed symptoms, and 14 patients tested positive for RT-PCR. PCR tests were also performed on four patients who did not develop the disease - two were positive and negative, each. The two negatives turned positive on a later antibody test, suggesting that there was an asymptomatic infection. In addition, all five patients who participated in the training for only a day developed symptoms and tested positive for PCR in a few days. Of the 64 people who underwent testing for antibodies as close contacts, all but one who was living together with a patient were negative on antibody testing.

Conclusions: The onset of COVID-19 occurred after the start of practice-based training continuously; therefore, the practice-based training was thought to be the main cause of the transmission. We speculate that the main factors behind the rapid spread of infection are as follows: during practice-based training, increased ventilation made it difficult to wear a mask; repeated loud vocalizations at close range; and the training pair was not fixed. Physical training without shouting and desk work, however, did not possess the risk of COVID-19, and avoiding certain situations at high risk of respiratory infections may have significantly reduced SARS-CoV-2 transmission. If personnel become infected with SARS-CoV-2, emergency measures should be devised by identifying patients and close contacts and facilitating the investigation of their behavioral history. Furthermore, evaluating and improving the effectiveness of infection control measures is necessary by ascertaining potentially infected persons by performing PCR tests, antigen tests, antibody tests, etc. in combination.