Chinese vaccine maker's two inactivated Covid vaccines have demonstrated efficacy against the virus, a study published in the prestigious US medical journal, Journal of the American Medical Association (JAMA), shows. The confirmation on the efficacy of these vaccines comes in the backdrop of criticism of Chinese vaccine makers for not sharing enough data on efficacy and safety of these vaccines.
The two vaccines developed by China National Biotech Group Co, which is a unit of Sinopharm, showed the efficacy of 72.8 per cent and 78.1 per cent, respectively. The current efficacy rate largely falls in line with Sinopharm's previous claims.
Notably, Chinese companies have aggressively targeted vaccine distribution in developing countries -- from Pakistan to Hungary and Serbia to Peru. The criticism came after the Covid-19 graph continued to show an upward momentum even after they had inoculated a sizeable population.
This also led to hurdles in approval from drug regulators in many countries, including Singapore, and the World Health Organisation (WHO). The JAMA study analysed as many as 40,832 volunteers from countries like the United Arab Emirates, Bahrain, Egypt and Jordan.
They were divided into three groups and either were administered both shots after three weeks, or a placebo. The results showed only 26 people developed Covid-19 infections, of which 21 had received both shots. It also showed that no volunteer developed a major illness after receiving the vaccine.
"The 2 vaccines had rare serious adverse events at a frequency similar to the alum-only control, and the majority were not related to the vaccinations. An exploratory analysis found that the 2 vaccines induced measurable neutralising antibodies, similar to results in the phase 1/2 trials," the study said.
The study results were submitted to the JAMA on March 17, which was accepted for publication on May 12.
The study also had several limitations. Firstly, it did not include pregnant women or those younger than 18 years; thus, the efficacy and safety of the inactivated vaccines in these groups remain unknown. Results from phase 1/2 trials among these groups have not been reported, but evaluation of the safety and immunogenicity of the two vaccines among children and adolescents is ongoing.
Second, the trial was mainly conducted in generally healthy, young men in the Middle East, and there was insufficient power to test the efficacy among those with chronic diseases, women, older adults, those in other geographic populations, and those with previous SARS-CoV-2 infections. This also includes people who are most vulnerable to severe COVID-19 cases and mortality.
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