Researchers plan to commence a clinical trial on new COVID-19 inactivated vaccine

A medical research team from the University of Hong Kong (HKU) will start a large-scale clinical trial on a new COVID-19 inactivated vaccine (Omicron variant) developed by China National Biotec Group (Sinopharm).

Led by Professor Ivan Hung, Chief of Division of Infectious Diseases and Clinical Professor of Department of Medicine, LKS Faculty of Medicine, The University of Hong Kong (HKUMed) and with the coordination and technical support by HKU Clinical Trials Centre (HKU-CTC), the study aims to evaluate the investigational vaccine's safety and immune response as a booster for adults and will last for around a year. 1,800 adult volunteers who have already received two or three doses of inactivated or mRNA COVID-19 vaccines will be recruited to take part in the study.


As of 26 May, 2022, the number of confirmed COVID-19 cases around the globe has surpassed 500 million with over 6 million deaths. Since the emergence of the pandemic in 2019, scientists worldwide have been striving to develop effective COVID-19 vaccines, hoping to resolve this public health emergency.

Even though different countries have been expediting vaccination, the original strain of SARS-CoV-2 is no longer the dominant disease-causing virus strain. It has been replaced by those more transmissible variants such as Alpha, Beta, Gamma, Delta and Omicron. The Omicron variant, in particular, has become the dominant strain, and has caused the latest wave of pandemic where confirmed cases reached a record high.

Currently, most COVID-19 vaccines in the market target the original strain of SARS-CoV-2. Although they still offer a certain degree of protection against the variants, previous studies have shown that the existing vaccines have significantly reduced immune responses against the Omicron variant, revealing the weaker protective effect of the current vaccines. In this regard, vaccines targeting the Omicron variant must be developed to prevent future outbreaks.

Vaccine development and research initiation process

On 24 November 2021, the Omicron variant was first reported to the World Health Organization (WHO) from South Africa. Within five days, the research team at the Department of Microbiology of HKUMed succeeded in being the first research team in Asia to have isolated the Omicron variant. It has been a significant milestone to the research and development of Omicron-targeting vaccines globally.

Hong Kong has no vaccine plant in town. In order to accelerate the development and production of vaccines against the variant, the team quickly exported the isolated virus to research institutions and vaccine manufacturers (including Sinopharm) in Mainland China, with the full support from the Governments of the Hong Kong SAR and China.

Sinopharm started vaccine development on 9 December, 2021 upon receipt of the isolated virus. With satisfactory immune responses observed from animal experiments, it promptly decided to initiate a clinical trial in Hong Kong by commissioning HKU-CTC as the coordinating centre in late-February this year.

Preparation for a clinical drug trial involves complicated steps - such as designing the trial protocol, building a research team, obtaining approvals from a research ethics committee and the Hong Kong Department of Health, developing project management and quality control plans, setting up an electronic data management system, engaging collaborating laboratories, setting out the study centre, procuring research equipment and consumables, importing investigational drugs, and developing volunteers recruitment strategy - and usually takes at least half a year to nine months.

Considering this trial's importance and urgency, all the parties paid special joint efforts to accelerate the completion of the said preparation process, which was completed in only three months, with the trial kick-started smoothly by late-May.

Research objective

This Omicron-targeting vaccine is developed by application of the inactivated vaccine technology, using killed Omicron virus to trigger people's immune responses and memory to the virus in order to generate specific immunological protection against Omicron.

If the investigational vaccine is proved to be safe and able to trigger adequate immune responses, it could be considered as a next generation COVID-19 vaccine, including application as a booster. It is expected to accelerate the implementation of relaxed infection control measures, cross-border mobility between Hong Kong and the Mainland/overseas countries, and ultimately a return to normal life.

Research method and arrangements

With the support of the Hong Kong SAR Government, this trial will take place at the community vaccination centre located at Sun Yat Sen Memorial Park Sports Centre in Sai Ying Pun. 1,800 volunteers will be recruited, including 900 adults who have received two or three doses of COVID-19 inactivated vaccine and 900 adults who have received two or three doses of COVID-19 mRNA vaccine.

They will be further assigned randomly into three groups, with one group receiving the original strain vaccine, and the other two groups receiving Omicron-targeting vaccines produced by two different manufacturing plants respectively. Each volunteer will receive two vaccine doses at a 28-day interval. Volunteers will need to return to the center for blood taking and follow-up during a one-year period.

All volunteers who are vaccinated in this trial will be granted a "Provisional Vaccine Pass" recognized by the Hong Kong government, which will allow holders to enter or remain on premises subject to the "Vaccine Pass" requirement.

The research team will analyze and submit the research data to regulatory authorities for evaluation after completion of the trial. Hopefully the vaccine could be approved for marketing registration and used by the public quickly.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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