• Pfizer and BioNTech issue a press release to announce that they have submitted a variation to the European Medicines Agency (EMA) requesting to update the Conditional Marketing Authorization of their coronavirus vaccine with data supporting a third booster dose in individuals 16 years of age and older. The same data, from a 306-person phase III trial was submitted to the US FDA, and the companies plan to file it with other regulatory authorities in the coming weeks. Source

• South China Morning Post publishes a report from non-peer-reviewed research finding that a booster shot of Sinovac’s coronavirus vaccine improves responses to the Delta variant. Four weeks after getting a third dose, levels of neutralizing antibodies were over 2½ times than those among either people who received two doses, or who had recovered from COVID-19. The researchers, who were from the Chinese Academy of Sciences, Peking University and Sinovac, said that third dose would also extend the duration of protection from the vaccine. Source

• China Daily reports results from a 56-person study conducted by researchers from the Chinese Academy of Sciences, Peking University and Sinovac Biotech. They found a third dose of Sinovac’s coronavirus vaccine administered six months after the second dose boosted “…neutralizing potency, breadth, and longevity of immune response against SARS-CoV-2,” including the Delta variant. Source

• A panel of experts at Chile’s Institute of Public Health approve Sinovac’s coronavirus vaccine for use in children ages six and over. Source

• A pre-print publication assesses efficacy and safety of mixing coronavirus vaccine doses of CanSino’s recombinant adenovirus type-5-vectored Convidecia with Sinovac’s inactivated virus-based CoronaVac in 300 healthy adults who were 18-59 years of age. Study participants had already received one (N=100) or two (N=200) doses of CoronaVac. Adverse events and neutralizing antibody titers among people who got two or three doses of CoronaVac versus one or two doses of CoronaVac plus one dose of Convidecia dose were compared at 14 and 28 days after vaccination. Researchers reported more frequent injection site reactions among people who received both vaccines versus those among people only given CoronaVac, although they noted mild-to-moderate adverse reactions in both groups. At 14 days post-vaccination, mixing induced significantly higher titers of neutralizing antibodies; overall, those who got three doses and different vaccines had at least a 78-fold increase in their average neutralizing antibody levels, while those who got three doses of the same vaccine had a 15.2-fold increase. In the two-dose group, those who got different vaccines had a 25.7-fold increase, versus a 6.2-fold increase among those who got two doses of CoronaVac. At 28 days after vaccination, average neutralizing antibody levels decreased, but they remained significantly higher among people who got different vaccines. The authors suggested that a mixing CoronaVac and Convidecia could be potentially associated with superior protection against SARS-CoV-2. Source

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