Objective To evaluate the preventive effect of Chinese medicine preventive decoction on close contacts of patients with coronavirus disease 2019（COVID-19）. Methods Chinese medicine preventive decoction was applied to people who were judged to be close contacts of patients with COVID-19 in Shandong Province from February 9 to February 18

2020 on the date of inclusion. The patients took the decoction for 5 consecutive days. Prescription composition: Huangqi（Radix Astragali seu Hedysari） 10 g

Baizhu（stir-fryed Rhizoma Atractylodis） 10 g

Fangfeng（Radix Saposhnikoviae） 10 g

Rendongteng（Caulis Lonicerae） 15 g

Lianqiao（Fructus Forsythiae） 10 g

Huangqin（Radix Scutellariae） 10 g

Chaihu（Radix Bupleuri） 10 g

Banxia（Rhizoma Pinelliae Preparata） 6 g

Huoxiang（Herba Pogostemonis） 10 g

Chenpi（Pericarpium Citri Reticulatae） 6 g

Fuling（Poria） 15 g

Beishashen（Radix Glehniae） 6 g

Shengjiang（Rhizoma Zingiberis Recens） 10 g

200 ml decoction per bag

2 bags a day

in the morning and evening. Scan code registration method was used to fill in the information voluntarily. The nucleic acid detection and disease status of close contacts was followed up during the 14-day isolation observation period

and the effective rate of the decoction prevention was calculated. Results Upto February 18

there were 689 close contacts from 16 cities in Shandong Province who registered and took the decoction by scanning the QR code. Among them

there were 392 males（56.89%） and 297 females（43.11%） aged from 3 to 77 years old

with an average of（27.91±14.80） years old. The exposure routes include 644 cases（93.47%） with one route of exposure

36 cases（5.22%） with two routes of exposure

7 cases（1.02%） with three routes of exposure

and 2 cases with five routes of exposure（0.29%）. Comparing with the reported cases of the Shandong Provincial Center for Disease Control and Prevention upto March 3

only one case appeared among the list

and this case was an asymptomatic infection with a positive nucleic acid test for the COVID-19. Conclusion Chinese medicine prevention combined with conventional preventive and isolation measures have a good preventive effect on the COVID-19. It is recommended to use Chinese medicine in such public health incidents in time and in order to effectively reduce the conversion rate of close contacts to confirmed patients.