S2 Vaccine Infection Events
In 2017, a brucellosis outbreak caused by S2 vaccination was reported in the Tianzhu county Gansu Province, China (Zhang P, 2018). An investigation showed that a total of 206 animal epidemic prevention controllers participated in the immunization work of S2 vaccination of sheep in the Tianzhu county from November to December in 2016. Fifty-one controllers were diagnosed with brucellosis by serology testing, and the rate of infection was 24.8%. All 51 individuals were RBPT-positive, in 36 cases SAT ≥ 1:100, the SAT ranged from 1: 50 to 1:100 in 15 cases. The blood samples from all patients were free of Brucellastrains. The vaccination work did not comply with the biosafety regulations was the main reason for this infection events, including improper handling in vaccination and limited understanding in pathogenicity of the S2 vaccine, inadequate personal protection, and imperfect emergency measures. The 94.13% cases (48/51) represent fatigue and sweat, fever in four cases, and swelling of testis in five cases. All the patients followed a unified therapeutic schedule of combined doxycycline and rifampin. The therapy was sustained for four weeks to six months based on the illness situation of patients. All the patients greatly improved. It is recommended that the animal husbandry and veterinary department should strengthen the protection knowledge of brucellosis and carry out vaccination according to the biological safety regulation.
On November 28, 2019, two students from the prevention and control technology team of Lanzhou Veterinary Research Institute of the Chinese Academy of Agricultural Sciences were found to have serum with anti-Brucella antibodies. Up to December 25, 671 serum samples from students and staff of the Lanzhou Animal Research Institute were screened. It was found that 181 persons were positive for anti-Brucella antibodies, and only one person had clinical symptoms. Active, free, and standardized treatment was carried out in patients who voluntarily agreed. Based on the investigation and many field test results, the expert concluded that from July 24 to August 20, 2019, the expired disinfectant was used in the production process of the S2 vaccine for animal use by Lanzhou biopharmaceutical factory of China animal husbandry, which resulted in incomplete sterilization of the waste gas from the production fermentation tank. The waste gas carrying the fermentation liquid formed the bacterial aerosols thought to be the main reason for this outbreak event. During the production period, the main wind direction in this area is the southeast wind, and the Lanzhou Veterinary Institute is located in the downwind direction of the Lanzhou biological pharmaceutical factory of China animal husbandry. Individuals become seropositive when they inhale or have mucous membrane contacts with infectious bacteria. The government sector has instructed the Zhongmu Lanzhou biopharmaceutical plant to focus on the brucellosis vaccine workshop to immediately carry out a comprehensive inspection on the implementation of the quality management specified for veterinary medicine in the whole plant, and to make the proper rectifications within a time limit. Without prior acceptance of the competent department of the industry, the brucellosis vaccine workshop should not resume production.