Clinical and epidemiological characteristics
As shown in Table 1 and Fig. 1, of all 504 patients reported as of January 12 in one city in China, 31(6.2%) patients were excluded due to the incomplete status of the information (including clinical outcomes and symptoms) by the publishing date, because complete information collection and organization requires more time and effort, and 473(93.8%) patients had completed characteristics. The median age was 47.6 years (IQR, 37–56; range, 2–93 years), and 222 (48.4%) were females. The median time from onset to diagnosis was 6.0 days (range: 0–23 days). Fever (71.7%) and cough (43.1%) were the most common symptoms, whereas diarrhea or anorexia (3.2%) were rare. 160 (33.8%) patients had a history of travel or residence to Wuhan. As of March 2, 2020, 51 (10.8%) were severe patients and 422 (89.2%) were non-severe patients. There were 425 cases discharged in total, 47 cases staying, and 1 death occurred in Wenzhou.
Table 1
Clinical and epidemiological characteristics of the COVID-19 patients
Early clinical symptoms | Wenzhou |
n/(%) |
Female sex–No., % | 222/473(48.4%) |
Age, Median (range) – years | 47.6(2–93) |
Travel or residence history within 14 days–No., % | |
Recently been to Wuhan | 160/473(33.8%) |
Outside Wuhan or WZ city | 24/473(5.1%) |
No | 289/473 (61.1%) |
Contact with source of transmission within 14 days–No., % | |
Contacted with people from Wuhan | 36/473(7.6%) |
Contacted with patient | 195/473(41.2%) |
Related the Yintai world trade center | 17/473(3.6%) |
Unknow | 225/473(47.6%) |
Discovered source of transmission | |
Undiscovered source of transmission | 61/473(12.9%) |
Symptoms | |
Asymptom–No., % | 23/473(4.9%) |
Symptoms | |
Fever | 339/473(71.7%) |
Headache | 31/473(6.6%) |
Cough | 204/473(43.1%) |
Sore throat | 39/473(8.2%) |
Sputum production | 50/473(10.6%) |
Fatigue | 57/473(12.1%) |
Diarrhea or castalgia | 15/473(3.2%) |
Muscle soreness | 29/473(6.1%) |
Disease severity | |
Severe–No., % | 51/473(10.8%) |
Clinical outcomes* | |
Discharge from hospital | 425/473(89.9%) |
Staying in hospital | 47/473(9.9%) |
Death | 1/473(0.2%) |
Time from onset to diagnosis (days) | |
Median (range) | 6.0(0–23) |
Features Of Asymptomatic Transmission Of Sars-cov-2 In Wenzhou
The point worth noting about this novel coronavirus pneumonia in Wenzhou city is the emergence of three kinds of unconventional cases. As shown in Table 1, there are 23 asymptomatic carriers accounts for 4.9% of the total patients, 36 (7.6%) patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact and 61 (12.9%) patients who had an unknown source of transmission, which suggests that asymptomatic carriers were also likely to have transmitted the virus. We divided all patients into two groups, one with a history of residence and travel in Wuhan and the other without, and then made a time distribution chart based on the time of onset of diseases. As indicated in Fig. 1, in addition to the change in the daily number of new cases with a history of residence and travel in Wuhan, we can see the change in the daily number of new cases with no link to Wuhan. 313 cases that had no link to initial epidemic area account for 66.2% of 473 cases and 160 cases with links to initial epidemic area account for 33.8% of the total. We described the curve of onset dates for both imported and local cases in Fig. 1. The earliest onset time of the imported cases was January 4, with a peak on January 21. The number of new cases gradually reduced after January 27. The local cases started to onset on January 6, numbers peaked on January 26, and decreased significantly after that. After February 14, no case occurred in Wenzhou.
An Outbreak Of Infection In A Public Place
Moreover, there was an outbreak of infection in a public place at the Yintai world trade center. On January 20, a 39-year-old saleswoman went to a local hospital for treatment by herself after breaking out with a fever at 38.5° C, accompanied by chills, dizziness, and headache, and symptoms of soreness and fatigue. She was subsequently diagnosed with COVID-19 on January 28, but the source of which is unknown. As of the date of publication, a total of 16 additional patients resulting from a contact within this mall have been confirmed, namely two staff members, two salesmen, one janitor, nine customers, and two individuals outside the mall but with close contact with one of the above.
Intervention And Surveillance Strategy
On January 21, 2020, Wenzhou government publicly announced the 24/7 telephone hotline to 13 local CDC and WZCDC in Wenzhou. At the same time, Wenzhou government mobilized the staffs of towns, districts, villages and grids to survey people from Wuhan and deploy primary medical staff to conduct the follow-up surveys. Moreover, with the aim of curbing the transmission of COVID-19, the government implemented strict intervention measures, such as implementing the hospital's pre-inspection and triage system, isolating suspected patients, strengthening the management of close contacts, strengthening the temperature measurement, disinfection in critical public places (stations, airports and other transportation sites), as well as publicizing hygiene knowledge [18, 19].
On January 22, 2020, Wenzhou government cancelled all public events and banned the wildlife trading. It also implemented a daily and zero-reporting systems for COVID-19 cases by Direct Network Report systems of Infectious Diseases and established proactive self-reporting channels for people returning from Wuhan and those with symptoms. Meanwhile, it publicly announced 33 24-hour fever clinical institutions and 9 designated medical institutions [19, 20].
On January 23, 2020, Wenzhou government launched the first-level response to major public health emergencies [21].
On January 24, 2020, Wenzhou government implemented stricter interventions. It suspended live poultry trading, postponed or canceled all large gatherings (including those in religious venues), and closed public entertainment venues (including theaters, video halls, amusement halls, dance hall, karaoke halls, Internet cafes, public bath, public swimming pools and cultural auditoriums). Body temperature testing and daily disinfection was implemented in public places. Individuals in Wenzhou must wear masks when going out. People who came to Wenzhou from Wuhan and their close contacts were required to quarantine at home for 14 days. If they had fever or respiratory symptoms, especially persistent fever, they must go to the local fever clinic in time [21].
On January 26, 2020, Wenzhou government set up a 24-hour public telephone hotline for citizens to encourage active self-report who had recently come to Wenzhou and had not undergone medical isolation [22].
On January 27, 2020, Wenzhou government implemented other intervention measures. People from Hubei Province, close contacts, and fever cases were required to self-quarantine at home or at designated locations for 14 days. Inter-provincial and inter-city shuttle buses and chartered passenger transport were suspended. The essential public places for public, such as farmers’ markets, large shopping malls or supermarkets, were required to reasonably adjust business hours and regularly have disinfection. Elderly care service agencies were required to temporarily implement closed management. All colleges, primary and secondary schools were required to suspend all gathering activities and were forbidden to start new semester on schedule while all kinds of extracurricular training activities were also put on hold. Wenzhou government required the society postpone resumption of work [23].
On January 29, 2020, 14 highway intersections entering Wenzhou were closed and the S1 line of the municipal railway and all ferries in Wenzhou were suspended [24].
From February 1 to February 15, 2020, Wenzhou introduced a regulation that only one person in each household could go out for purchase every 2 days [25, 26].
Starting from February 16, 2020, a normalization mode of the epidemic prevention and control was implemented in Wenzhou and the "Wenzhou Health Code" was promoted and applied throughout the city. Villages (residential areas) and communities continued to implement closed management. But when a cluster of cases break out, the community must immediately implement full or partial closed management according to the risk level. When one confirmed case occurred, the whole building must implement closed management. During the closed management period, cadres of the towns (streets) and villages (communities, residential) were on rotational duty 24 hours a day and were obliged to provide psychological counseling services. Village (resident) residents were in principle not allowed to enter and exit except for special circumstances [27, 28].
Personnel and three kinds of people who were ready to return to work, return to school or return to Wenzhou could apply online for "Wenzhou Health Code" by themselves. They would open Alipay and search for "Wenzhou Health Code", fill in personal health information, and submit the application after confirmation (after successful application). After application, the "health code" is available in the Alipay "card package" certificate column. Applicants must fill in the information truthfully, and those who fail to fill in factfully could potentially face legal consequences that would be shown in the personal integrity record. Those who caused serious medical consequences would be held accountable in accordance with the law. After the application was reviewed, a three-color "health code" would be generated, including green, yellow and red code. Those who displayed a "green code" and whose temperature measurement was normal were allowed to pass while those who displayed a "yellow code" would be subject to 14-day and 7-day home quarantine observation according to the epidemic-risk areas and low-risk areas respectively. Those that displayed the "red code" were send to designated hospital for treatment or medical isolation and observation for 14 days. Villages (residential areas) and communities were continually implemented closed-loop management in Wenzhou. When entering the implementation of one-way temperature measurement, the village and community personnel shall rely on the “health green code” passes, and those who had not applied for the health code could enter with valid certificates. Individual with a “yellow health code” could enter for the first time, and strictly followed the regulations to implement home isolation observation after entering. The closed-loop measures were implemented by the local township (street) government for open communities without management and security. In key areas for prevention and control, the relevant counties (cities, districts) could appropriately extend the village (resident) travel control measures as deemed appropriate.
From February 20 to 22, 2020, work and production activities gradually resumed in Wenzhou. The relevant checkpoints were removed and the highway entrances and exits were simultaneously reopened [29].
Evaluation Of Effects For Prevention And Control Strategy
We estimated that the basic reproductive number (R0) to be 2.75 (95%CI: 2.37–3.23) for the cases with symptom onset between January 9 and January 22 by Exponential Growth method, thus we expected the proportion of infections would increase thereafter in Wenzhou. The results showed that in the early stage of the epidemic, COVID-19 in Wenzhou had strong infectivity, consistent with results of previous studies [17].
Based on the study of Li Q, et al [17], we estimated the effective reproduction number (Rt) of Wenzhou from January 11 to March 2, 2020 with a 7-day moving average, which was an index to evaluate the effect of prevention and control strategy. Rt fluctuated within the range of 2.50 to 3.74 from January 11 to January 16 while gradually reached the peak of 3.74 on January 16. Rt gradually decreased after January 16 and decreased to 1.00 on January 30. Rt continually decreased and reached the lowest point (0.03) on February 21. Though the trend of Rt was slightly increasing between February 22 to March 2, the estimation of Rt still below 0.38. The daily estimated values of Rt were shown in Table 2 and Fig. 2.
Table 2
Estimates of the effective reproduction number (Rt) for laboratory-confirmed COVID-19 cases from January 11 to March 2, 2020
Date | Mean | Std | Median | 95% CI |
2020/1/11 | 3.69 | 1.84 | 3.38 | 1.00 ~ 8.08 |
2020/1/12 | 2.98 | 1.49 | 2.73 | 0.81 ~ 6.53 |
2020/1/13 | 3.06 | 1.37 | 2.86 | 0.99 ~ 6.26 |
2020/1/14 | 2.50 | 1.12 | 2.34 | 0.81 ~ 5.13 |
2020/1/15 | 3.21 | 1.14 | 3.08 | 1.39 ~ 5.79 |
2020/1/16 | 3.74 | 1.08 | 3.63 | 1.93 ~ 6.13 |
2020/1/17 | 3.29 | 0.88 | 3.21 | 1.80 ~ 5.22 |
2020/1/18 | 2.07 | 0.60 | 2.02 | 1.07 ~ 3.40 |
2020/1/19 | 1.75 | 0.47 | 1.71 | 0.96 ~ 2.78 |
2020/1/20 | 1.74 | 0.40 | 1.71 | 1.05 ~ 2.60 |
2020/1/21 | 1.84 | 0.35 | 1.82 | 1.21 ~ 2.59 |
2020/1/22 | 2.10 | 0.33 | 2.08 | 1.51 ~ 2.79 |
2020/1/23 | 1.85 | 0.27 | 1.84 | 1.36 ~ 2.41 |
2020/1/24 | 1.83 | 0.23 | 1.82 | 1.40 ~ 2.31 |
2020/1/25 | 1.72 | 0.19 | 1.71 | 1.36 ~ 2.12 |
2020/1/26 | 1.76 | 0.17 | 1.76 | 1.44 ~ 2.12 |
2020/1/27 | 1.44 | 0.14 | 1.44 | 1.18 ~ 1.73 |
2020/1/28 | 1.30 | 0.12 | 1.30 | 1.07 ~ 1.54 |
2020/1/29 | 1.10 | 0.10 | 1.09 | 0.91 ~ 1.30 |
2020/1/30 | 0.91 | 0.09 | 0.91 | 0.75 ~ 1.09 |
2020/1/31 | 0.82 | 0.08 | 0.82 | 0.68 ~ 0.98 |
2020/2/1 | 0.76 | 0.07 | 0.75 | 0.62 ~ 0.90 |
2020/2/2 | 0.63 | 0.06 | 0.63 | 0.52 ~ 0.76 |
2020/2/3 | 0.60 | 0.06 | 0.60 | 0.49 ~ 0.72 |
2020/2/4 | 0.54 | 0.06 | 0.54 | 0.44 ~ 0.65 |
2020/2/5 | 0.48 | 0.05 | 0.47 | 0.38 ~ 0.59 |
2020/2/6 | 0.49 | 0.05 | 0.49 | 0.39 ~ 0.60 |
2020/2/7 | 0.46 | 0.05 | 0.46 | 0.36 ~ 0.57 |
2020/2/8 | 0.46 | 0.05 | 0.46 | 0.36 ~ 0.58 |
2020/2/9 | 0.43 | 0.05 | 0.43 | 0.33 ~ 0.54 |
2020/2/10 | 0.43 | 0.06 | 0.42 | 0.32 ~ 0.54 |
2020/2/11 | 0.38 | 0.06 | 0.38 | 0.28 ~ 0.50 |
2020/2/12 | 0.40 | 0.06 | 0.40 | 0.29 ~ 0.53 |
2020/2/13 | 0.36 | 0.06 | 0.36 | 0.26 ~ 0.49 |
2020/2/14 | 0.30 | 0.06 | 0.30 | 0.20 ~ 0.43 |
2020/2/15 | 0.19 | 0.05 | 0.19 | 0.11 ~ 0.30 |
2020/2/16 | 0.15 | 0.04 | 0.14 | 0.07 ~ 0.25 |
2020/2/17 | 0.11 | 0.04 | 0.10 | 0.04 ~ 0.20 |
2020/2/18 | 0.12 | 0.05 | 0.12 | 0.05 ~ 0.23 |
2020/2/19 | 0.04 | 0.03 | 0.03 | 0.00 ~ 0.11 |
2020/2/20 | 0.05 | 0.03 | 0.04 | 0.01 ~ 0.13 |
2020/2/21 | 0.03 | 0.03 | 0.02 | 0.00 ~ 0.11 |
2020/2/22 | 0.04 | 0.04 | 0.02 | 0.00 ~ 0.13 |
2020/2/23 | 0.04 | 0.04 | 0.03 | 0.00 ~ 0.17 |
2020/2/24 | 0.06 | 0.06 | 0.04 | 0.00 ~ 0.21 |
2020/2/25 | 0.08 | 0.08 | 0.05 | 0.00 ~ 0.28 |
2020/2/26 | 0.10 | 0.10 | 0.07 | 0.00 ~ 0.38 |
2020/2/27 | 0.14 | 0.14 | 0.10 | 0.00 ~ 0.52 |
2020/2/28 | 0.20 | 0.20 | 0.14 | 0.00 ~ 0.73 |
2020/2/29 | 0.28 | 0.28 | 0.19 | 0.01 ~ 1.02 |
2020/3/1 | 0.39 | 0.39 | 0.27 | 0.01 ~ 1.44 |
2020/3/2 | 0.55 | 0.55 | 0.38 | 0.01 ~ 2.03 |