Low effectiveness rates, missing data spur concern amid PRC’s talk of combining COVID-19 vaccines
Revelations that the People’s Republic of China (PRC) is considering combining different coronavirus vaccines to compensate for the low effectiveness of its domestically manufactured shots have again spotlighted the PRC’s lack of transparency since the deadly virus first was detected in Wuhan, China, in late 2019.
In April 2021, the PRC’s disease control chief admitted that Chinese-developed vaccines offer low protection against COVID-19, The Associated Press (AP) reported. “We will solve the issue that current vaccines don’t have very high protection rates,” Gao Fu said at a conference in Chengdu, a city in southwest China. “It’s now under consideration whether we should use different vaccines from different technical lines for the immunization process.”
Gao quickly sought to backtrack, claiming that he wasn’t referring specifically to the effectiveness of Chinese vaccines, according to the AP. Later that month, however, an official with China National Biotech Group announced that the company, a subsidiary of state-owned Sinopharm, has a plan for “sequential use” of its vaccines, the online news magazine The Diplomat reported. Sequential immunization entails combining different vaccines to increase effectiveness.
With demand outpacing supply, researchers worldwide are studying the possibility of combining vaccines. “Mixing and matching COVID-19 vaccines raises several potential complications,” noted a February 2021 article in the journal Science. “One is regulatory: What if, say, only one is authorized for emergency use? Another is immunological: Whereas some vaccines share the same underlying technology platforms — such as the messenger RNA technology used by both the Pfizer-BioNTech collaboration and Moderna — others do not.”
Public health authorities caution that COVID-19 vaccines are not interchangeable and that more trial data is needed. “The safety and efficacy of a mixed-product series have not been evaluated,” the United States Centers for Disease Control and Prevention (CDC) states.
The World Health Organization (WHO) in May 2021 issued emergency-use approval to a COVID-19 vaccine developed by Sinopharm. The vaccine, pictured, is estimated to be 79% effective among adults. It is the first Chinese vaccine approved for emergency use by the WHO, which also is weighing similar approval for the CoronaVac vaccine manufactured by the Chinese company Sinovac. Clinical trials of CoronaVac have produced varying efficacy rates, including just 51% in one study.
In comparison, the Moderna and Pfizer-BioNTech vaccines produced by drugmakers in the United States and other Western nations were about 95% effective in clinical trials, according to the CDC. Unlike Moderna and Pfizer-BioNTech, the Sinopharm and Sinovac vaccines use an inactivated coronavirus.
More than 500 million doses of the Sinopharm and Sinovac vaccines had already been supplied within China and shipped to other nations ahead of emergency-use approval, a designation that allows a vaccine to be included in COVAX, the global vaccination initiative co-led by the WHO, Reuters reported.
The U.S. is the largest contributor to COVAX, donating U.S. $2 billion in March 2021 with another $2 billion planned through 2022, according to the U.S. State Department. “People everywhere should have access to rigorously tested, safe and effective COVID-19 vaccines,” U.S. Secretary of State Antony J. Blinken said in announcing the contribution.
Meanwhile, questions of incomplete or limited trial data continue to shadow the PRC’s vaccine development. Even as it approved Sinopharm, the WHO cited data gaps. “Few older adults (over 60 years) were enrolled in clinical trials, so efficacy could not be estimated in this age group,” the agency noted, calling for nations using the vaccine to “conduct safety and effectiveness monitoring” among older age groups.
A week before the WHO’s anticipated mid-May decision on CoronaVac, agency officials said they were still awaiting requested information from Sinovac, Reuters reported.
Sinopharm also has not released phase 3 clinical trial data to scientists for independent assessment, and it’s unclear how robust the vaccine will be against coronavirus variants, The New York Times newspaper reported.
“Chinese researchers were among the first to begin developing vaccines against COVID-19 in early 2020, but they have yet to publish full trial results,” noted a May 2021 article in the international journal Nature.
Officials worldwide have condemned the PRC’s withholding of vital information from public health organizations and scientists, contending that the pattern of concealment has compounded a pandemic that has infected about 160 million people globally, killing more than 3 million and devastating national economies.
Four days after issuing emergency-use approval for Sinopharm, the WHO announced that it was reviewing data related to a spike in coronavirus cases in the Seychelles, an archipelago nation of about 95,000 people in the Indian Ocean. Among individuals there testing positive for COVID-19 in late April and early May, 37% had been fully vaccinated, Reuters reported. Almost 60% of the Seychelles’ population is fully vaccinated. Of those, 57% received Sinopharm and 43% received the AstraZeneca vaccine.
IMAGE CREDIT: THE ASSOCIATED PRESS