BEIJING, April 14 (Xinhua) -- As COVID-19 has spread to more than 200 nations and regions and infected over 1.9 million people globally, countries across the world have joined efforts to develop vaccines, in which lies humankind's best hope of prevailing over the pandemic.

The research and development of vaccines usually take years. But to meet the urgent need of containing COVID-19, various countries are taking different technological approaches in the race against time to develop vaccines.

VACCINES, "ULTIMATE WEAPON"

"We are really building the plane while flying it." Dr. Gregory Poland, director of the Mayo Clinic's Vaccine Research Group in Rochester, the U.S. state of Minnesota, used this metaphor to describe the current phase of vaccine research and development.

"When we encounter these new viruses, especially coronaviruses, the long-term hope for prevention and control lies in vaccines," Poland, who is also editor-in-chief of the scientific journal Vaccine, told a symposium in March.

The World Health Organization (WHO) in March declared COVID-19 a pandemic, prompting a fiercer battle against the novel coronavirus.

Vaccines have always been an ultimate weapon of humankind to fight epidemics. Since cowpox vaccinations -- an embryo of vaccines -- were born in the 18th century, contagious diseases raging across the world including smallpox and Measles have all been effectively controlled through vaccines.

COVID-19 is no exception.

However, the development of vaccines is a time-consuming, high-risk and high-cost endeavor, which includes early-stage design, animal experiment and three phases of clinical trials.

The first phase of clinical trial, which tests the safety of a vaccine, requires no less than 20 days; the second phase needs 200 to 300 volunteers to test the efficiency of a vaccine, and lasts at least one month; the third phase -- a larger scale of vaccination to assess a vaccine's side effects -- varies from three months to five months.

This means that if everything progresses smoothly, it will take at least six months to conclude that a COVID-19 vaccine is effective.

WHO Director-General Tedros Adhanom Ghebreyesus said in February that the first vaccines for the novel coronavirus could be ready in 18 months.

MULTIPLE TECHNOLOGICAL APPROACHES

Scientific researchers have found that coronavirus spike protein binds the peptidase domain of Angiotensin-converting enzyme 2 (ACE2) at the surface of a cell to cause an infection.

The clear interpretation of the infection mechanism of the novel coronavirus has laid a solid foundation for vaccine target selection and research and development.

Vaccine preparation has experienced three generations of improvement: live attenuated vaccines and inactivated vaccines; polysaccharide vaccines, subunit vaccines and polypeptide vaccines; nucleic acid vaccine represented by DNA and mRNA vaccines, as well as gene-engineered vectored vaccines represented by adenovirus vector vaccines.

Globally, the development of COVID-19 vaccines incorporates all three generations of technological approaches.

China has adopted five technological approaches to developing COVID-19 vaccines, namely inactivated vaccines, genetic engineering subunit vaccines, adenovirus vector vaccines, nucleic acid vaccines, and vaccines using attenuated influenza virus as vectors, the Joint Prevention and Control Mechanism of the State Council told a press conference.

Currently, three research organizations have entered the first phase of clinical trial.

The mRNA vaccine -- jointly developed by the National Institute of Allergy and Infectious Diseases subordinate to the U.S. National Institutes of Health, and U.S. biotech firm Moderna -- started its clinical trial in March.

The recombinant vaccine developed by the Institute of Military Medicine under China's Academy of Military Sciences started its clinical trial on March 16.

The DNA vaccine developed by U.S. company Inovio Pharmaceuticals has also entered the clinical testing phase.

As of April 4, another 60 COVID-19 vaccine candidates are at the phase of clinical research, said the WHO, adding that subunit vaccines account for as much as one third, followed by 13 kinds of RNA vaccines.

Research teams including China's Fudan University and Hong Kong University, Queensland University in Australia, Britain's Imperial College London, and India's Cadila Pharmaceuticals Limited, are racing against time to develop vaccines to protect people from COVID-19.

COORDINATED GLOBAL EFFORTS

Though humankind has created a new record of combating infectious disease during the past over two months, the development of COVID-19 vaccines still faces various challenges.

Other challenges lie in the uncertainty of vaccine clinical testing. Noting that three phases of clinical trials need to be done in virus-stricken areas, Xu Xiaoning, chair in Human Immunology & Head, Centre for Immunology & Vaccinology at Imperial College London, said that after the situation with the epidemic in many countries improves, it will become difficult to recruit volunteers to assess the efficiency of vaccines, and this may affect how soon the vaccines could reach the market.

Stressing that vaccine development is a "complex process," Xu said the research and development of COVID-19 vaccines requires at least one year and a half to two years.

If the international community strengthens cooperation, the process may be speeded up, he added.

Right now the pandemic is "a global emergency, and every aspect of the response needs coordination," said Dr. David Nabarro, co-director of the Institute of Global Health Innovation at Imperial College London, who has been appointed as a special envoy for the response to the 2019 novel coronavirus outbreak.

"It's necessary to be sure that there is coordination on identification of candidate vaccines and establishing principles of efficacy and safety, supporting countries with licensing, obviously, doing all the trial work together, and then just deciding on how best to manufacture large quantities and to administer to the whole population," he said.

From international organizations to regional organizations, from non-governmental organizations and research institutes to corporations, the whole world has taken actions to extend multi-level collaboration to develop COVID-19 vaccines.

And China has been an irreplaceable part of the global efforts to tackle the pandemic.

As of the end of March, Chinese scientists had published more than 50 essays about the novel coronavirus on internationally-renowned medical journals, including The Lancet and The New England Journal of Medicine, to share new findings in tracing the origin of the coronavirus and its infection mechanism, among others.

China's research and development of COVID-19 vaccines feature high tranquility. The five technological approaches it adopted are all open to international cooperation, which is already underway, Xu Nanping, vice minister of science and technology, told a press conference on March 26.

In addition, Chinese enterprises have also proactively participated in the construction of the global vaccine industrial chain. China's pharmaceutical company Shanghai Fosun is cooperating with German pharmaceutical company BioNTech on the clinical trials and follow-up commercialization of an mRNA vaccine in China.

Noting China has a very strong capacity to produce these vaccines, Xu said future research and development of the vaccines will enable China to expand global production scale at a faster speed, so as to protect healthy people from getting infected. Enditem



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