The need for clarity on the safety and efficacy of China’s vaccines has taken on more urgency after Sinopharm revealed it had already vaccinated roughly a million people even before the completion of clinical trials. The campaign has alarmed overseas scientists who say it exposes people to undue risks.
Chinese officials have repeatedly assured the public that the country’s coronavirus vaccines are safe, while providing few details. Last month, Liu Jingzhen, the chairman of Sinopharm, said that no one among the people who had received the company’s vaccines had experienced any adverse reactions. He said that “only a few had mild symptoms.”
Confused by the all technical terms used to describe how vaccines work and are investigated? Let us help:
- Adverse event: A health problem that crops up in volunteers in a clinical trial of a vaccine or a drug. An adverse event isn’t always caused by the treatment tested in the trial.
- Antibody: A protein produced by the immune system that can attach to a pathogen such as the coronavirus and stop it from infecting cells.
- Approval, licensure and emergency use authorization: Drugs, vaccines and medical devices cannot be sold in the United States without gaining approval from the Food and Drug Administration, also known as licensure. After a company submits the results of clinical trials to the F.D.A. for consideration, the agency decides whether the product is safe and effective, a process that generally takes many months. If the country is facing an emergency — like a pandemic — a company may apply instead for an emergency use authorization, which can be granted considerably faster.
- Background rate: How often a health problem, known as an adverse event, arises in the general population. To determine if a vaccine or a drug is safe, researchers compare the rate of adverse events in a trial to the background rate.
- Efficacy: The benefit that a vaccine provides compared to a placebo, as measured in a clinical trial. To test a coronavirus vaccine, for instance, researchers compare how many people in the vaccinated and placebo groups get Covid-19. Effectiveness, by contrast, is the benefit that a vaccine or a drug provides out in the real world. A vaccine’s effectiveness may turn out to be lower or higher than its efficacy.
- Phase 1, 2, and 3 trials: Clinical trials typically take place in three stages. Phase 1 trials usually involve a few dozen people and are designed to observe whether a vaccine or drug is safe. Phase 2 trials, involving hundreds of people, allow researchers to try out different doses and gather more measurements about the vaccine’s effects on the immune system. Phase 3 trials, involving thousands or tens of thousands of volunteers, determine the safety and efficacy of the vaccine or drug by waiting to see how many people are protected from the disease it’s designed to fight.
- Placebo: A substance that has no therapeutic effect, often used in a clinical trial. To see if a vaccine can prevent Covid-19, for example, researchers may inject the vaccine into half of their volunteers, while the other half get a placebo of salt water. They can then compare how many people in each group get infected.
- Post-market surveillance: The monitoring that takes place after a vaccine or drug has been approved and is regularly prescribed by doctors. This surveillance typically confirms that the treatment is safe. On rare occasions, it detects side effects in certain groups of people that were missed during clinical trials.
- Preclinical research: Studies that take place before the start of a clinical trial, typically involving experiments where a treatment is tested on cells or in animals.
- Viral vector vaccines: A type of vaccine that uses a harmless virus to chauffeur immune-system-stimulating ingredients into the human body. Viral vectors are used in several experimental Covid-19 vaccines, including those developed by AstraZeneca and Johnson & Johnson. Both of these companies are using a common cold virus called an adenovirus as their vector. The adenovirus carries coronavirus genes.
- Trial protocol: A series of procedures to be carried out during a clinical trial.
In October, Zheng Zhongwei, a senior health official, said the government had established a “follow-up program” to track the people who had been vaccinated, though he gave no details.
Sinovac Biotech, a Beijing-based private vaccine maker, has already begun exporting its vaccines to countries like Indonesia and Brazil. Sinopharm, which has another vaccine in late-stage testing, has said it is preparing to deliver 500 million doses worldwide, according to the state-run newspaper Science and Technology Daily.
It is unclear whether the Emirates will start using the Chinese vaccine — which Sinopharm developed with the Beijing Institute of Biological Products — for mass inoculations. The government had already approved the vaccine for emergency use in September for frontline workers at risk of contracting Covid-19.
Some other countries where Sinopharm is conducting trials are counting on Chinese vaccines to help protect their populations. Morocco says it is preparing to vaccinate 80 percent of its adults, relying initially on a Sinopharm vaccine, though it would wait for China to approve the vaccine, according to Médias24, a Moroccan news website.
The Chinese vaccines are also appealing to developing countries because they could be easier to distribute. Sinopharm has said its vaccines need only be refrigerated at temperatures of 2 to 8 degrees Celsius (or 35 to 46 degrees Fahrenheit) and could remain stable for up to three years. In contrast, Pfizer and Moderna’s vaccines, which are made with genetic materials that fall apart when they thaw, require industrial freezers, making transportation and storage more challenging.