A cluster of pneumonia associated with the SARS-Cov-2 outside of Wuhan related to a house-warming banquet.

Dear editor,

We read the recent published review by Han and colleagues in this journal with great interest, which described the epidemiology, clinical features and treatment of Corona Virus Disease 2019 (COVID-19) and mentioned that people who were asymptomatic or in incubation period can be the sources of infection.

An ongoing epidemic caused by a new coronavirus, which was formally named as SARS-Cov-2 by Coronavirus research group (CSG) of the International Committee, started in late 2019 in Wuhan, Hubei province, China and had become a worldwide public health concern. A total of 81300 cases were confirmed in China so far (March 20, 2020) and increasingly more cases were confirmed abroad, especially in Europe. On Jan 30, 2020, the WHO Emergency Committee declared the outbreak as a global health emergency. Furthermore, it still remains unclear about the origin, transmission mode and incubation period of the SARS-Cov-2. Previous research has demonstrated the person-to-person transmission of the novel Coronavirus.

Here, we report the clinical features of a cluster of seven patients suffered from pneumonia associated with the SARS-Cov-2 in Lishui City of Zhejiang Province, China. Epidemiological, demographic, clinical, laboratory, radiological and treatment data were collected through detailed interviews with each patient and electronic medical records. Laboratory confirmation of the virus was performed using RT-PCR by Lishui Center for Disease Control and Prevention (CDC). Case definitions of confirmed COVID-19 are in accordance with the interim guidance from a rapid advice guideline.

The first enrolled patient (Patient A) returned to Lishui from Wenzhou on Jan 18, 2020 and participated a house-warming banquet. Two days later, he suffered with fever, chill, cough and generalized weakness, and was hospitalized on Jan 23, later diagnosed as COVID-19 on Jan 25. Patient B, father of patient A, presented with cough and fever on Jan 21 and was diagnosed on Jan 27. On the same day, patient C was diagnosed as COVID-19 with primary symptoms of cough and sputum. Tracking the medical history of patient C, he began to cough on Jan 16 (two days before the banquet) when he was still in Yongkang, a city adjacent to Lishui. Patient D developed a bad cough on Jan 22 and patient E presented with similar symptom on Jan 26. They were diagnosed on Feb 1 and Feb 2, respectively. Patient F was hospitalized on Jan 30 with fever, chill, cough and generalized weakness and diagnosed as COVID-19 on Feb 1. All the above six patients attended the same house-warming banquet. Oddly enough, patient G, who did not attend the same party, had fever on Feb 1 and was soon diagnosed on Feb 2. Tracing the history of epidemiology, she had dinner with patient C on Jan 24. It is worth noting that the cluster of seven patients did not go to Wuhan or Hubei province in the preceding 14 days, and they denied any exposure with wild animals, confirmed COVID-19 patients or febrile patients (Fig. 1).

Fig. 1

Timeline of symptom onset of the cluster patients related to a house-warming banquet.

Two possible scenarios of transmission exist. The first and most likely scenario is that patient A acquired the infection from an asymptomatic patient in Wenzhou (a city with most cases in Zhejiang province) before Jan 18, 2020. This period overlapped with the time period during the announcement of the first case of COVID-19 in Wenzhou (symptom onset on Jan 4, diagnosed on Jan 21) according to the Zhejiang Provincial Health Committee (http://www.zjwjw.gov.cn/col/col1659205/index.html). The other five patients (B∼F) attended the same house-warming banquet and had lunch together in a crowded, noisy hotel restaurant with patient A. Even more, patient B and C had taken the same car with patient A from Lishui back to Qingyuan. As a result, all the five patients were in close contact with patient A, who most likely had been infected before. Then patient G was infected because she was exposed to patient C. The second scenario is that patient C acquired the infection in Yongkang, because he had begun coughing two days before the banquet. As described in the first scenario, other patients were all in close contact with him and got infected. Though the median incubation varies from 3∼6.4 days according to the previous studies, , it is sometimes difficult to calculate the incubation period accurately such as patient A and patient C. Regardless of how the virus transmitted among the seven patients, it further indicated that the SARS-Cov-2 infection could cause clustering onset. Quarantine and keeping social distance paly pivotal roles in the prevention of local outbreak of COVID-19. The exact transmission mode still needs to be further studied.

The seven patients were aged 23–72 years old. Except patient G, the remaining 6 patients were all males. All patients had no chronic disease except patient C, who had mania years ago. On admission, cough (7/7), generalised weakness (7/7), sore throat (7/7), fever (4/7) and insomnia (4/7) were the main symptoms. The range of incubation period from exposure to symptoms was 3∼11 days (Table 1 ).

Table 1

Summary of clinical features of the cluster patients infected with SARS-Cov-2 (on admission).

Index	Patient A	Patient B	Patient C	Patient D	Patient E	Patient F	Patient G
Age(Year)	45	72	51	36	51	23	47
Sex	Male	Male	Male	Male	Male	Male	Female
Occupation	Business man	Farmer	Farmer	Farmer	Farmer	Civil servant	Farmer
Smoke	Y	Y	N	Y	Y	Y	N
Alcohol drinking habit	Y	Y	N	Y	Y	Y	N
Chronic medical illness	N	N	Mania	N	N	N	N
Interval between Admission to hospital and Symptom onset (days)	3	4	Uncertain	7	4	1	0.5
Incubation period (days)	Uncertain	3	Uncertain	4	8	11	8
Presenting symptoms and sign
Fever	Y	Y	N	N	N	Y	Y
Chill	Y	Y	N	N	N	N	N
Cough	Y	Y	Y	Y	Y	Y	Y
Nasal congestion	Y	N	N	N	Y	N	Y
Rhinorrhoea	Y	N	N	N	Y	N	Y
Sneezing	Y	N	N	N	Y	N	Y
Dyspnea	Y	N	N	N	N	N	N
Sore throat	Y	Y	Y	Y	Y	Y	Y
Chest pain	N	N	N	N	N	N	N
Generalized weakness	Y	Y	Y	Y	Y	Y	Y
Diarrhoea	Y	N	Y	Y	N	N	N
Nausea and(or) Vomiting	Y	N	Y	N	N	N	N
Headache	N	N	N	N	N	N	Y
Insomnia	Y	Y	Y	N	N	N	Y
Body temperature (°C)	39	38	36.3	36.8	37	38.4	37.5
Oximetry saturation (%)	98	95	98	99	99	99	98

N: no; Y: yes.

Regarding the inflammatory indicators, leucocytes, neutrophils, lymphocytes and procalcitonin (PCT) of all the patients were normal and C-reactive protein (CRP) were slightly increased in three patients on admission. Liver function was mildly abnormal in one patient and no patient developed renal dysfunction. Abnormalities in chest CT images were detected among all patients, among which 5 patients showed bilateral pneumonia while only 2 patients showed unilateral pneumonia. All patients showed multiple mottling and ground­glass opacities. Compared with COVID-19 patients initially found in Wuhan, all patients in this study had mild to moderate symptoms. No complications such as acute respiratory distress syndrome, renal dysfunction, myocardial injury and secondary bacterial infection occurred. Symptoms and abnormalities in chest CT scan of all the 7 patients disappeared or significantly improved after antiviral and supportive treatments.

In conclusion, this study further indicates that the SARS-Cov-2 infection can cause clustering onset, person-to-person transmission and intercity spread, and it is more likely to happen in crowded places. We urgently need to pay attention to the scale of transmission from asymptomatic or mildly symptomatic patients during the early phase of infection.

Ethics approval

The study has been approved by the research ethics committee of Lishui Peoples’ Hospital (LLW-FO-403). Written informed consent has been waived in light of the urgent need to collect clinical data.

Declaration of Competing Interest

None