A senior figure at a Chinese pharmaceutical company that tested Covid-19 vaccines on its own executives before human trials took place has defended the decision, saying they were “leading by example”.
China National Biotec Group (CNBG), which has two experimental vaccines in the final stage of human trials, has been under fire for trying them on 180 executives in the group and its mother company China National Pharmaceutical Group (Sinopharm) in March, days before the vaccines were approved for human trial.
The volunteers included Sinopharm chairman Liu Jingzhen, along with CNBG’s chairman Yang Xiaoming and vice-president Zhang Yuntao, who took shots in March.
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“We are very confident in our own vaccines,” Zhang said. “We are in charge of the vaccine development and we need to lead by example, so we tested the vaccine on our own bodies.”
Testing drugs on one’s employees is deemed unethical under modern pharmaceutical protocols, but sometimes in China it is considered a noble sacrifice.
Chinese media have recounted how Nobel laureate Tu Youyou tested an anti-malaria drug on herself in 1972 and Gu Fangzhou, a Chinese virologist who developed a domestic oral polio vaccine, tested it on his baby son.
Major General Chen Wei, who led a team of military scientists developing a Covid-19 vaccine in partnership with Chinese firm CanSino, also took a jab before their vaccine was given to volunteers recruited for human trials.
Zhang said the CNBG and Sinopharm executives were not part of clinical trials, which are randomised and controlled, but had been monitoring antibody levels to try to gauge the vaccines’ effectiveness. The phase 1 and 2 trials for CNBG’s two Covid-19 vaccines were conducted in China, and the data was published in the journal Cell and the Journal of the American Medical Association.
“We couldn’t test directly the protectiveness of the vaccines, but we can compare the antibody levels with those of the recovered Covid-19 patients,” Zhang said. “The antibody level and duration [of high antibody level] are even higher. My arm went blue from drawing blood dozens of times.”
CNBG is testing two vaccines in various countries for safety and protectiveness data, with which the company can apply for regulatory approval. Although protectiveness data was not yet complete, the safety data was very satisfactory, Zhang said.
China has four vaccines in phase 3 human trials, three of which – including both of CNBG’s – use the traditional but no longer popular “inactivated” method that involves killing the full virus under a high level of biosecurity. Few of the world’s nearly 200 Covid-19 vaccine candidates are using the method.
Moncef Slaoui, an immunologist and the scientific head of the US’ national Covid-19 vaccine plan Operation Warp Speed, told Science magazine last month that developing inactivated vaccines for Covid-19 was “not a good idea”, because administering an inactivated respiratory syncytial virus vaccine in the 1960s had “enhanced disease”, and inactivating large amounts of virus particles posed a biosafety risk.
None of the announced vaccine candidates selected by Warp Speed used actual viruses. Some used mRNA (messenger ribonucleic acid), which tells cells how to make proteins. An mRNA vaccine is designed to mock an attack by the protein spikes with which the coronavirus invades human cells, and trigger an immune response to any future coronavirus-infected cells carrying the same spikes.
Zhang said CNBG had considered mRNA vaccines before choosing the more traditional inactivated option.
“There has been no approval of mRNA vaccines for humans before and its safety needs long-term monitoring,” Zhang said. “Covid-19 vaccines are not simply about technological innovation. It will be used on healthy people of all age groups, so safety comes first.”
The company is seeking conditional approval for its vaccines, which could be granted this year.
“Having the trial in multiple places is to test the vaccine among different [racial and ethnic] groups,” he said. “More continuous monitoring [of safety data] is required before such vaccines get full approval.”
Even longer monitoring will be needed after the approval, if received. Administering a vaccine to a large population can expose antibody-dependent enhancement (ADE): antibody protection that has the potential to amplify the infection or trigger harmful immune responses.
The CNBG vaccines did not show potential for ADE during animal trials, nor has it been detected among the roughly 400,000 people who have taken the experimental vaccines under China’s emergency use programme or in the trials held in various countries. But that does not mean ADE will definitely not occur.
“Clinical trials will not be the end of the vaccine development,” Zhang said. “It needs continuous monitoring.”
More from South China Morning Post:
- Chinese firm finds hostility and smears add hurdles to Covid-19 vaccine race
- Coronavirus: WHO backed China’s emergency use of experimental vaccines, health official says
This article Chinese execs took firm’s Covid-19 vaccine pre-trials ‘to lead by example’ first appeared on South China Morning Post