Chinese Sinopharm and Coronavac Coronavirus Disease 2019 (COVID-19) shots have been administered in many countries, accounting for approximately 50 percent of doses delivered globally. However, their effectiveness is being questioned, with some studies showing that the immunity provided by two vaccine doses is slowly waning.
Both Sinopharm and Coronavac vaccines are inactivated vaccines that make use of dead SARS-CoV-2 viruses. Such vaccines tend to be less potent, as they trigger immune reactions to several viral proteins.
In contrast, the newly developed mRNA vaccines, like those from Moderna and Pfizer, target the virus’ spike protein that is used by the organism to enter human cells. As such, mRNA vaccines are more targeted than inactivated vaccines. However, even the mRNA vaccines have been shown to have waning efficacy.
“You don’t choose the target with inactivated vaccines, you just throw in all these different antigens,” Jorge Kalil, a physician and immunologist at the University of Sao Paulo Medical School, Brazil, said to Nature. Studies have shown that the protection offered by Chinese vaccines tends to drop off after a few months.
A Hong Kong study found that an individual inoculated with Coronavac has a lower antibody response one month after their second dose when compared to Pfizer. A study from China found T cells and B cells specific for SARS-CoV-2 just five months after the second dose of Sinopharm.
Success
You are now signed up for our newsletter
Success
Check your email to complete sign up
In Thailand, only 60 percent of those who had Coronavac had developed high levels of neutralizing antibodies a month after the second shot, compared to 86 percent for the AstraZeneca vaccine. Moreover, three months after the second dose of Coronavac, the antibody level fell to 12 percent.
There have been several reports of countries suffering from viral outbreaks despite having a large proportion of citizens inoculated with Chinese vaccines, including nations such as Mongolia, Seychelles, and Bahrain.
In June, when 50 to 68 percent of the population in these three countries were fully vaccinated, they still ranked among the top 10 nations with the worst COVID-19 outbreaks.
Many countries are now beginning to avoid Chinese vaccines and pursue other options, which has impacted China’s trade data. In August, China’s human vaccine exports fell to 1.96 billion dollars from 2.48 billion dollars in July, a drop of 21 percent.
Thailand, which initially ordered Chinese vaccines, was forced to suspend orders and opt for Western vaccines due to pressure from protestors.
“The government already knows that studies and research show inactivated virus vaccines are less effective against virus mutations when compared to mRNA-based vaccines… We should know the vaccination rate that excludes all two-dose Sinovac shots because the immunity may not be enough anymore. Any regions that are ready can then reopen,” Wiroj Lakkhanaadisorn, an opposition lawmaker in Thailand, said to Bloomberg.
In mid-September, Beijing announced that it had fully vaccinated one billion people. However, reports from that time showed COVID-19 outbreaks occurring in several parts of the country, including Fujian province and Harbin city. In Fujian, schoolchildren were contracting COVID-19 as well.
“One child cried for two hours at home before leaving for the hospital… My own eyes welled when I saw these children in protection suits getting out of the ambulance,” a nurse said, adding that children as young as five to six years old were getting COVID-19.
