Sinovac Biotech (NSDQ: SVA) reported that a third dose of its inactivated SARS-CoV-2 vaccine improved the protection of CoronaVac® by 60%, including protection from the Delta variant. The third dose was administered six months after the second shot, when the efficacy of the vaccine was already in decline. CoronaVac® was approved by WHO under emergency rules. Sinovac said the study provides a "theoretical basis" for a third dose of the vaccine, implying more studies would be required before regulatory approval.

In the study, a third dose of CoronaVac® induced broader neutralization for variants of concern (VOCs), particularly the Delta variant. It created a rapid immunological memory response and a long-lasting humoral response.

In the study of immunogenic profiles of antibodies from three and two-dose CoronaVac® recipients and convalescents, the findings showed three-dose subjects had better neutralization breadth in VOCs, expeditious recall, and long-lasting humoral immune response. An analysis of 171 complex structures of neutralizing antibodies identified structure-activity correlation and revealed very potent, VOCs-resistant, and broad-spectrum patches.

In May, Sinovac began the process of obtaining approval for CoronaVac in Europe. It also brought its third China production plant for the vaccine online, doubling its annual capacity to 2 billion doses. Sinovac’s COVID-19 vaccine  has received emergency use approval (EUA) in over 30 countries including China.

Sinovac's product portfolio includes vaccines for:

• enterovirus71 (EV71),
• hepatitis A and B,
• seasonal influenza,
• H5N1 pandemic influenza (avian flu),
• H1N1 influenza (swine flu),
• varicella vaccine and
• mumps.

 The company is developing a number of new products including:  

• a Sabin-strain inactivated polio vaccine,
• pneumococcal polysaccharides vaccine,
• quadrivalent influenza vaccine and
• the SARS-CoV-2 (commonly referred to as COVID-19) vaccine. 

See our other articles on Sinovac. 

Disclosure: none.