Development of an inactivated vaccine candidate for SARS-CoV-2.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented public health crisis. Because of the novelty of the virus, there are currently no SARS-CoV-2-specific treatments or vaccines available. Therefore, rapid development of effective vaccines against SARS-CoV-2 are urgently needed. Here, we developed a pilot-scale production of PiCoVacc, a purified inactivated SARS-CoV-2 virus vaccine candidate, which induced SARS-CoV-2-specific neutralizing antibodies in mice, rats, and nonhuman primates. These antibodies neutralized 10 representative SARS-CoV-2 strains, suggesting a possible broader neutralizing ability against other strains. Three immunizations using two different doses, 3 or 6 micrograms per dose, provided partial or complete protection in macaques against SARS-CoV-2 challenge, respectively, without observable antibody-dependent enhancement of infection. These data support the clinical development and testing of PiCoVacc for use in humans.

Preparation and characterization of SARS in-house reference antiserum.

A reference antiserum for SARS is in urgent need in the development of SARS vaccine and other serological test of SARS research. Convalescent serum was collected from clinical confirmed patient. ELISA, Western-blotting and neutralization assay detected specific antibody against SARS coronavirus. This antiserum was prepared as in-house reference antiserum, freeze-dried and sealed in ampoules. The potency of this reference antiserum is defined to be 52.7 U after extensive calibration. Further, collaborative studies for the evaluation of this serum are needed in order to satisfy the requirements for international reference antiserum.

[The study on the 0, 12 month vaccination schedule' of Healive inactivated hepatitis A vaccine in children].

OBJECTIVE: To evaluate the safety, immunogenicity and fit dosage of Healive inactivated hepatitis A vaccine (HAV) in children. METHODS: A total of 85 susceptible aged 4 - 10 years with HAV seronegative children, had been enrolled from two adjacent villages in a county. The volunteers were randomized allocated into two groups and to receive a priming dose of 250 U/0.5 ml/dose or 500 U/1.0 ml/dose of Healive vaccine, produced by Sinovac Biotech Co, Ltd. A booster of the same dose was given at 12th month. Local and systemic side effects were examined and seroconversion rate as well as geometric mean titers of anti-HAV antibody were tested at 3-week, 12-month after the primary dose and at 1 month after the booster dose. RESULTS: The vaccine was well tolerated in both groups. At 21 days after the primary dose, the seroconversion rates were 94.4%, 100.0% and geometric mean titers (GMT) were 195 mIU/ml and 370 mIU/ml in 250 U and 500 U groups respectively. At 12 months after the primary dose, the seroconversion rate of anti-HAV was 100.0%, and GMT raised to 361 mIU/ml, 456 mIU/ml (P > 0.05) respectively. One month after the booster dose, GMT raised to 14 893 mIU/ml, 21 696 mIU/ml. CONCLUSION: GMT of the 0, 12 month schedule was higher than other schedule after the booster vaccination. The Healive inactivated vaccine can be used for emergency vaccination. The Healive inactivated vaccine produced by Sinovac Company Ltd was safe and highly immunogenic. Two hundred and fifty U/dose was considered appropriate for children.