Scientists say vaccine candidates are safe

Special: Fight against the new coronavirus

Chinese experts reassure investors after a British patient gets sick using a similar drug

Top CanSino Biologics scientists said on Wednesday that COVID-19 vaccine candidates were generally safe and effective, with clinical trials of the same type of vaccine developed in the UK when participants were suspected of having life. Reassure investors after suspension-threate side effects.

On Wednesday, a Phase 3 clinical trial of a British vaccine developed by the University of Oxford and the biotechnology company AstraZeneca experienced symptoms similar to a rare but severe spinal inflammatory disorder called cross-sectional myelitis. It was discontinued worldwide after the UK trial, according to the US medical news website Stat News.

The volunteer’s diagnosis and cause of the illness have not been identified, but she has been reported to be improving and will be discharged soon, said Pascal Soriot, CEO of AstraZeneca. On the other hand, if there is any link between the disorder and the vaccine, an independent investigation is being conducted.

UK pharmaceutical and healthcare product regulators will soon decide whether trials can be resumed. Candidate trials in the United Kingdom, Japan, Brazil, South Africa and the United States have been suspended.

CanSino Biologics Chief Scientist Zhu Tao reassured investors at a meeting Wednesday, and the company’s co-developed Chinese vaccine candidate and biomedical expert Chen Wei is generally safe, effective and medical. Reported no serious side effects requiring attention.

The Chinese recombinant adenovirus vector vaccine (called Ad5-nCoV) uses an attenuated and modified cold virus as a vector to introduce some of the genetic material of the novel coronavirus into the body and cause the disease. Train to recognize and repel.

Zhu often compares the two because Chinese and British vaccines use the same technology, but there are subtle differences in the untrained eye.

For example, the Chinese vaccine adenovirus came from humans, and the British vaccine vector came from chimpanzees. Given the genetic similarity to human chimpanzees, the two viral vectors are very similar, but the differences between them are not well understood and are still under investigation.

“It may ultimately result in preference, cost, and availability,” said Beijing’s biology professor, who demanded anonymity. “Since humans are barely exposed to these viruses, scientists have long used chimpanzee-derived viral vectors, so our immune system is less likely to attack these harmless vectors, and vaccines. Is guaranteed to be effective. “

“On the other hand, human-derived viral vectors are safe because they come from our body, but that also means that more people may have immunity to these vectors. , The vaccine may not be effective per dose. As an elderly person, booster shots may be needed. “

Zhu states that Ad5-nCoV is expected to provide two years of protection, and current evidence states that a single dose is sufficient to provoke a sufficient immune response, but twice. The protection can be further strengthened by administration of. The current demographics covered by the vaccine are over 18 years old, and a version available for groups aged 6-18 is under development.

In response to vaccine safety concerns, Zhu may have misunderstood China’s findings as different vaccine developers use different test standards, definitions and virus strains and should not read carefully. Said it could be confusing.

According to the British medical journal The Lancet, in a phase II trial of Chinese vaccines, 9% of the 253 volunteers who received the high-dose vaccine and one of the 129 volunteers in the low-dose group “Serious grade 3 side effects”.

However, the Grade 3 category of Chinese studies primarily refers to fever, allowing scientists to distinguish fever from skin irritation and other minor reactions. The study stated that the grade 3 response was “self-limited and resolved within 3-4 days without medication.”

In traditional clinical trials, side effects are assessed on a scale of 1 to 5, grade 3 effects are serious reactions requiring medical intervention, grade 4 is life-threatening and requires hospitalization, and grade 5 is fatal. It is a target. Cancer Institute.