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Chinese authorities have already approved multiple Covid-19 vaccines for emergency use in the country, and nearly a million Chinese have already been vaccinated with one candidate.
Several local governments are already placing orders for domestically developed vaccines, although the Chinese government has not confirmed how many people it intends to vaccinate as part of the emergency approval.
The first international shipments of the vaccine, from the private Chinese company Sinovac, also arrived in Indonesia this week in preparation for a mass vaccination campaign ahead of expected local approval.
China is developing at least five Covid-19 vaccines from four producers. These vaccines, which have been developed very quickly, are largely based on traditional vaccine manufacturing techniques, such as inactivation of the virus.
These methods provide some benefits to vaccines over others. For example, some of the vaccines developed in China can be stored in normal refrigerators, which makes distribution easier. This is in contrast to the Pfizer jab, which should be kept around -70 degrees Celsius.
Too early to tell
The results of clinical trials of vaccines developed by companies based in China have been published for the most part in major international journals.
These journals are independently reviewed by members of the global scientific community who provide open and critical analysis prior to acceptance of the work. They are also some of the most trusted medical research journals in the world, a testament to the quality of science being conducted in China.
Emergency approval for the use of several of the vaccines developed in China has exceptionally come early in the clinical trial process. This has likely raised concerns that security due diligence is not being followed.
However, these are exceptional times. It should also be noted that the vaccine developed by Pfizer, and which received emergency approval in the UK, has yet to receive full regulatory approval and phase 3 clinical trials will soon conclude.
The early release of these vaccines to the general population should really be seen as an unofficial extension of phase 3 clinical trials, rather than a definitive seal of approval.
People who have been vaccinated should continue to be monitored for adverse events and lasting immune responses. Any subsequent reports of serious adverse events due to vaccination will halt use of that vaccine, but could also erode confidence in vaccination and acceptance of the vaccine internationally.
So who are the companies developing these vaccines in China and what do we know about them?
Sinovac
Sinovac Life Sciences is a private Chinese company that focuses on the research, development and manufacture of vaccines for humans and animals. It has developed and commercialized six vaccines for human use and one for animals.
The company’s Covid-19 vaccine, called CoronaVac, is an inactivated vaccine. It was recently shipped to Indonesia.
It is made by growing the Covid-19 virus in laboratories and treating it with a chemical that inactivates it. The chemical blocks the virus in a state where it cannot replicate, but its structure is maintained, allowing the body to recognize it as foreign and generate an immune response.
It is also given with an adjuvant, an immune stimulant that is given to enhance the protective response.
Having shown a substantial immune response and minimal safety concerns (primarily mild pain at the injection site) in phase 1 and 2 clinical trials, CoronaVac is now in phase 3 clinical trials.
Phase 3 trials have recruited tens of thousands of participants to test the efficacy and safety of the vaccines and are being carried out in Brazil, Indonesia and Turkey.
Brazilian officials said in October that the vaccine is safe, amid phase 3 trials.
However, the death of a participant in the phase 3 trial in October prompted Brazilian authorities to temporarily halt the Sinovac trial. Although the details of the death were unclear, the trial was quickly resumed and the Brazilian institute involved in the trial confirmed that the participant’s death was not related to the vaccine. The results of phase 3 trials can be published in a matter of days.
Despite not knowing the results of phase 3 trials, a condition that is generally required to receive regulatory approval, CoronaVac has been approved for emergency use in China to vaccinate high-risk groups since July 2020.
This emergency approval likely followed positive data from Phase 1 and Phase 2 trials of the vaccine.
Sinopharm
Sinopharm is a Chinese state-owned company that researches, develops and distributes vaccines and other pharmaceutical products. It has produced a number of drugs that have been approved by the United States Food and Drug Administration and by the EU authorities.
The two Covid-19 vaccines that Sinopharm is developing are inactivated vaccines. Both follow an inactivation process similar to that of the Sinovac vaccine and also use adjuvants to stimulate an immune response.
Both have undergone phase 1 and phase 2 clinical trials with encouraging results. They produced an effective immune response in the participants and reported adverse reactions, such as injection site pain and fever, which were mild and resolved quickly. Certain doses generated SARS-CoV-2 specific antibodies in all participants in the phase 1 and 2 trial.
Both vaccines are currently in phase 3 trials. Once again, despite incomplete clinical trials, both are reported to have been distributed for use by Chinese government officials and healthcare workers.
Additionally, the United Arab Emirates, an ongoing phase 3 trial site, granted emergency use for one of Sinopharm’s vaccines in September, following testing on 31,000 participants.
Despite this unusual early use of vaccines, phase 3 testing is still required to determine if it is safe and effective in the long term.
CanSino Biologics
This Chinese company has developed a Covid-19 vaccine based on an adenovirus in partnership with the Chinese Academy of Military Medical Sciences. Adenovirus cannot cause disease on its own, but is used to deliver a coronavirus protein.
Phase 2 clinical trials reported that the vaccine is safe and induces significant immune responses in the majority of participants.
This vaccine was also approved for limited use by the Chinese military in June, at the time of the conclusion of phase 2 trials.
Phase 3 clinical trials, which began in August, are ongoing in countries like Saudi Arabia.
The China-based company Anhui Zhifei Longcom has developed a Covid-19 protein subunit vaccine. Subunit vaccines use a purified part of the virus, a protein, to trigger an immune response. Phase 3 clinical trials have recently started.
There have not yet been any announcements or published reports of the results of the phase 1 and 2 trials.
Adam taylor is a Early Career Research Leader, Emerging Viruses, Inflammation and Therapeutics Group, Menzies Health Institute Queensland, Griffith University
This story first appeared in The Conversation. To read the original, Click here.
