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.