Table 1.
Top 30 keywords extracted from electronic notices over time.
| Rank | Stage 1: 1 Jan. to 26 Jan. 2020 | Stage 2: 27 Jan. to 22 Feb. 2020 | Stage 3: 23 Feb. to 7 May 2020 | Stage 4: 8 May to 31 August 2020 | ||||
|---|---|---|---|---|---|---|---|---|
| Sentences (n = 211) | Sentences (n = 523) | Sentences (n = 863) | Sentences (n = 1268) | |||||
| Keywords after Processing (n = 376) | Keywords after Processing (n = 512) | Keywords after Processing (n = 558) | Keywords after Processing (n = 637) | |||||
| Keyword | TF-IDF | Keyword | TF-IDF | Keyword | TF-IDF | Keyword | TF-IDF | |
| 1 | Person on duty | 1.8 | Operation | 1.1 | Hospital inflow | 1.4 | Caregiver | 1.4 |
| 2 | Nation of occurrence | 1.4 | Daegu-Gyeongbuk | 1 | Public health center | 1.3 | Health | 1.3 |
| 3 | Sore throat | 1.4 | Texting | 0.9 | Endoscope | 1.2 | Cohort ward | 1.3 |
| 4 | Countermeasure | 1.2 | Case definition | 0.9 | Level D | 1.2 | Mobile | 1.2 |
| 5 | Restrict visits | 1.2 | Travel restrictions | 0.9 | Schedule | 1.2 | Texting | 1.2 |
| 6 | Cough | 1.1 | Management | 0.9 | Central disaster control headquarters | 1.2 | Suspected case | 1.2 |
| 7 | Pneumonia of unknown origin | 1.1 | Visited China | 0.9 | Infectious disease | 1.1 | Intensive care unit | 1.2 |
| 8 | Visited China | 1.1 | Attend | 0.9 | Resident caregiver | 1.1 | Commuting to and from work | 1.2 |
| 9 | Respiratory symptoms | 1.1 | Shutdown | 0.9 | Convalescent hospital | 1.1 | Academic conference | 1.2 |
| 10 | Caregiver for the sick | 1 | Overseas travel | 0.9 | Support | 1.1 | Restriction of work | 1.1 |
| 11 | Specimen | 1 | Drug utilization review (DUR) | 0.8 | Clinic | 1.1 | Agency head | 1.1 |
| 12 | Vigilance stage | 1 | N95 mask | 0.8 | Within 14 days | 1 | Asymptomatic | 1.1 |
| 13 | Hospital beds | 1 | Specimen | 0.8 | Infectious disease report | 1 | Public health center | 1.1 |
| 14 | Admission | 1 | Recommendation | 0.8 | On duty | 1 | Resident caregiver | 1.1 |
| 15 | Contact | 1 | Restrict visits | 0.8 | Salary | 1 | Restaurant | 1.1 |
| 16 | Infectious disease response center | 0.9 | Occurred area | 0.8 | Target person | 1 | Meal | 1.1 |
| 17 | Personal protective equipment | 0.9 | Fever | 0.8 | Cohabitant | 1 | Epidemiological investigation | 1.1 |
| 18 | Examination | 0.9 | Caregiver | 0.8 | Visitor | 1 | Emergency room | 1.1 |
| 19 | Surgical mask | 0.9 | Screening questionnaire | 0.8 | Hospital rooms | 1 | Attention phase | 1.1 |
| 20 | Management | 0.9 | Screening clinic | 0.8 | Seoul or Gyeonggi | 1 | Organizer | 1.1 |
| 21 | Epidemic | 0.9 | Unknown origin pneumonia | 0.8 | Screening questionnaire | 1 | Central disaster control headquarters |
1.1 |
| 22 | Doctor | 0.9 | Risk factors | 0.8 | Health Insurance Review and Assessment Service | 1 | Clinics | 1.1 |
| 23 | Movement | 0.9 | Negative result | 0.8 | National safe clinics | 1 | Treatment | 1.1 |
| 24 | Entry to country | 0.9 | Visited Japan | 0.8 | Risk factors | 1 | Event | 1.1 |
| 25 | Provide information | 0.9 | Reception | 0.8 | Negative results | 1 | 2 m | 1 |
| 26 | Proper use of PPE | 0.9 | Information | 0.8 | Healthcare personnel | 1 | Personal protective equipment | 1 |
| 27 | Entry to hospital | 0.9 | Restriction | 0.8 | Self-quarantine | 1 | Recommendation | 1 |
| 28 | International Traveler Information System (ITS) | 0.8 | Action | 0.8 | Transmission | 1 | Karaoke | 1 |
| 29 | Reinforcement | 0.8 | Procedure | 0.8 | Mass outbreak | 1 | Occupational Safety and Health Management Office | 1 |
| 30 | Upgrade | 0.8 | Entrance | 0.8 | Prevention of spread | 1 | Operation | 1 |
| 31 | Alarm signal | 0.8 | Statistical Reporting | 0.8 | Environmental management | 1 | Approval | 1 |
| 32 | Stages of Interest | 0.8 | Control | 0.8 | Drug utilization review (DUR) | 0.9 | Facility inspection | 1 |
| 33 | Local public health center | 0.8 | Academic conference | 0.8 | Polymerase chain reaction (PCR) | 0.9 | Trainees | 1 |
| 34 | Return to country of origin | 0.8 | Test results | 0.7 | Infection controls | 0.9 | Negative results | 1 |
| 35 | Cough etiquette | 0.8 | Sharing | 0.7 | Recommendations | 0.9 | Admission | 1 |
| 36 | Visitor management | 0.8 | Return to nation | 0.7 | Confirmed cases | 0.9 | Religious facilities | 1 |
| 37 | Screening clinic | 0.8 | Hospital visitor | 0.7 | Fever | 0.9 | Attendance | 1 |
| 38 | Risk alert phase | 0.8 | Visited Southeast Asia | 0.7 | Fever respiratory clinic | 0.9 | Control | 1 |
| 39 | Press release | 0.8 | Visited Macao | 0.7 | Department head | 0.9 | Infection controls | 0.9 |
| 40 | Mass outbreak | 0.8 | Restrict visits | 0.7 | Screening clinic | 0.9 | Wearing personal protective equipment | 0.9 |