China's COVID vaccine induces immune response within weeks, appropriate for emergency use

On November 17, Sinovac Biotech said in a statement that its Inactivated COVID-19 Vaccine CoronaVac developed by Sinovac Life Sciences (Sinovac LS) has produced a quick immune response against the SARS-CoV-2. Although the experimental vaccine produced lesser antibodies than in individuals who had recovered from a respiratory ailment. While still in the mid-stage trials, the scientists said that vaccine presented adequate safety, and efficacy in providing immunization. The findings were published in the journal The Lancet and the trials involved more than 700 volunteers. 

“Our findings present that CoronaVac is able to induce a fast antibody response inside 4 weeks of immunization by giving two doses of the vaccine at a 14-day interval,” Zhu Fengcai, one of the authors of the paper said. Further, he added, “We imagine that this makes the vaccine appropriate for emergency use throughout the pandemic.” China’s Sinovac is in the Part III clinical trials stage in Indonesia, Brazil, and Turkey. CoronaVac is one of three experimental COVID-19 vaccines being produced by China. Gang Zeng, a Sinovac researcher stated that the Sinovac’s vaccine can be stored at normal fridge temperatures of 2 to 8 degrees Celsius (36°-46°F), whereas Pfizer vaccine needed storage below -70 degrees celsius. “This would offer some advantages for distribution to regions where access to refrigeration is challenging,” Zeng said in the study. 

Earlier, Sinovac had halted the phase III clinical trial of CoronaVac sponsored by Butantan Institute in Brazil due to a serious adverse event (SAE) reported in one of the participants. The company, however, submitted a report by the Data and Safety Monitoring Board (DSMB) to Anvisa. After evaluating the data, Anvisa made a very timely decision to resume clinical research. "The suspension and resumption of such studies are common in clinical research. A suspension does not necessarily mean that the product under investigation has any issue of quality, safety or efficacy", Anvisa said.

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Double-blinded, placebo-controlled

China’s “CoronaVac” was also approved by the National Medical Products Administration (NMPA) for a clinical trial in adolescents and children. The randomized, double-blinded, and placebo-controlled phase I/II clinical trial was conducted among adolescents between the ages of 3-17 years old was approved by the Ethics Committee of the Hebei Provincial CDC. Volunteers were administered low dosage (300SU/dose) and medium dosage (600SU/dose) with two-dose immunization with 28-day intervals.

Meanwhile, the company’s Phase I/II clinical trials of CoronaVac in adults (18 to 59 years old) and elderly volunteers (60 years old and above) were conducted in Jiangsu and Hebei Provinces, China. “No serious vaccine-related adverse events were reported. Both seroconversion rates in adults and elderly volunteers were above 90%, indicating favorable safety and immunogenicity of CoronaVac,” the company announced. 

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