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BEIJING, July 24, 2020 /PRNewswire=KYODO JBN/ --

A news report by Science and Technology Daily:

Good news. On July 20th, The Lancet published two papers online at the same

time, revealing the results of clinical trials for two COVID-19 vaccines. From

China and the United Kingdom respectively, the two stars on the track of

adenovirus vector vaccine display a one-on-one competition.

What are the similarities and differences between the two vaccines in terms of

clinical trial design and results despite that they have taken the same R&D

approach? What are the characteristics of Chinese vaccines' R&D? How to

perceive the potential of Oxford's vaccine?

Two-dose Protection or Single-dose immunity, which is more effective?

Led by Chen Wei, academician at China Academy of Engineering and researcher at

Academy of Military Medical Sciences, Ad5-nCoV is the first COVID-19 vaccine

around the globe to enter Phase II clinical trial. The most important feature

of the trial is that eligible participants over 60 years old are involved,

consisting 13% of the 508 total participants.

CanSino Biologics Inc. (CanSinoBIO) is in partnership with Chen's team

regarding vaccine development. The president of CanSinoBIO, Yu Xuefeng,

received interview by Science and Technology Daily. He noted, "From the

perspective of trial design, the two trials share the same mechanism, namely

inducing balanced humoral and cellular immune responses. There are also

differences. We hope that a single-dose can be effective in the time of

pandemic whereas the Oxford team further testes a "two-dose" protection."

According to news from Oxford website, Professor Andrew Pollard, head of the

Oxford Vaccine Group, said: "We saw the strongest immune response in the 10

participants who received two doses of the vaccine, indicating that this might

be a good strategy for vaccination."

Yu held a different view. He thought that the "fastest would be a single-dose

injection" under the trend of the pandemic. The result of Chinese Vaccine's

Phase II clinical trial showed that 95% of the participants in the high-dose

group and 91% in the low-dose group showed either cellular or humoral immune

responses at day 28 after vaccination.

"This means that single-dose vaccine not only takes effect quickly, but also

has potential to be  effective of vaccination."

One thing to note is that the elderly participants have a higher tolerability

for the vaccine whereas they also display a lower level of immune response.

Chen's idea is widely quoted by the media. Once infected by the virus, the

elderly is faced with high risks of severe diseases or even death. Therefore,

they are an important target population for the COVID-19 vaccine.

Yu pointed out that with an additional dose, the immune response will be

effectively intensified. The effect of two-dose vaccination was demonstrated  

in the clinical trial for the Ebola vaccine developed by CanSinoBIO with the

same technology. For clinical trials in the future, how to achieve better

protection for the elderly can be explored.

Chimpanzees or human being, which vector is safer?

Except for their efficacy, what about the safety of the two vaccines?

The AZD1222 vaccine by Oxford and AstraZeneca combines a weakened version of a

common cold virus (adenovirus) that causes infections in chimpanzees and the

genetic material of the SARS-CoV-2 virus.

According to Yu, Ad5-nCoV uses adenovirus type 5 as vector, a weakened version

of common adenovirus that can result in the infection of human beings rather

than chimpanzees. "Although some participants may have 'existing immunity' due

to their infection of adenovirus type 5 and impact the immune response,

Ad5-nCoV ensures safety to the greatest extent from the source of the

adenovirus vector."

Currently, the two vaccines are almost equally safe in terms of "safety

evaluation" observed by public information from the media. Andrew Pollard and

colleagues report their phase 1/2 randomized trial of one injection of

chimpanzee adenovirus-vectored COVID-19 vaccine. Local and systemic adverse

events such as fatigue, headache, and local tenderness occurred commonly in

COVID-19 vaccines, but were tolerable and mostly ameliorated by paracetamol. No

serious adverse events occurred.

Chen and colleagues reported results from a phase 2 randomized trial of

single-dose immunization schedule of Ad5-vectored COVID-19 vaccine. Most

injection site and systemic solicited reactions from the participants in China

were mild or moderate. Adverse reactions occurred in this study includes fever,

fatigue, headache, and injection site pain.

According to the comment article written by Professor Naor Bar-Zeev and

Professor William J Moss, "Overall, the results of both trials are broadly

similar and promising, notwithstanding differences in the vector, in the

geographical locations of the populations studied, and the neutralization

assays used. These COVID-19 vaccine trials are small so inferential caution is

warranted, but the explorations are laudable. Ethnic diversity in both these

trials was very limited."

"Equal Global Access to COVID-19 Vaccine": China and UK's Common Goal and

Commitment

"It is good news," Dr. Mike Ryan, executive director of the WHO's emergencies

program, said at a press conference at the organization's Geneva headquarters

shortly after the data was published in The Lancet. "In generating T-cell

responses and generating neutralizing antibodies, this is a positive result.

But again, there is a long way to go. We now need to move into larger-scale

real-world trials."

He noted that once one of the vaccines is proven effective, the next challenge

will be ensuring that there are enough doses to distribute globally.

"CanSinoBIO has always been in a strategic partnership with Academician Chen's

research team and the Oxford University research team respectively. However,

CanSinoBIO chose to cooperate with Chen's research team in the early stage of

COVID-19 vaccine development," Yu said. "But it is undeniable that the

cooperation between the Oxford team and AstraZeneca has potential advantages in

the recruitment of volunteers for the Phase III clinical trial."

Although the vaccine developed by Oxford team still lags behind CanSinoBIO

regarding the level of adenovirus vaccine production line, its developing

progress is expected to be "accelerated" with the aid of huge funding and the

support of the global vaccine distribution network, and eventually achieve

large-scale production after the results of its Phase III clinical trial are

revealed.

Author: Fang Linlin  Translated by Long Yun & Lu Zijian

SOURCE: Science and Technology Daily