HKU and Emerging Infectious Diseases: 1997 Avian Flu, 2003 SARS, and 2020 COVID-19

The death of a 3-year-old boy. A novel coronavirus whose sequence two international laboratories "had to revise" to match. A vaccine that took a wager on an intranasal spray rather than an injection. Over nearly three decades, the microbiology and public health teams of The University of Hong Kong (HKU) have been thrust into the global frontline of emerging infectious disease response three times. This article traces the specific research contributions of HKU across these three epidemics chronologically, verifying claims of "world-first" status one by one and proactively seeking counter-evidence. In accordance with our editorial policy (00–12 Neutral Fact Zone), historical, deceased, or award-winning scientists are recorded by their real names.

This article is the event timeline main entry for HKU's flagship strength in emerging infectious diseases. For laboratories and research platforms (SKLEID, HKU-Pasteur, the InnoHK Centre for Virology, Vaccinology and Therapeutics), representative scholars and international honours, and pathogens named with the "HKU" designation, see hku-named-pathogens.md; for the overall structure of the State Key Laboratories, see institutes-and-labs.md; for the Faculty of Medicine and Queen Mary Hospital, see ../11-medical-hospital/.

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# I. 1997: H5N1 Avian Influenza and the "Chicken Cull" Containment

# 1.1 The Index Case: A 3-Year-Old Boy

In 1997, Hong Kong witnessed the world's first confirmed human infection with the highly pathogenic avian influenza H5N1 virus. According to the US CDC Museum Digital Exhibits^※ and a review in Clinical Infectious Diseases^※, in May 1997, a 3-year-old boy died from a respiratory illness, and tests confirmed the infection was linked to the influenza A(H5N1) virus—representing the first known human case caused by this virus. A further cluster of cases emerged between November and December of that year, bringing the annual total to 18 confirmed cases with 6 deaths. The transmission route was directly from poultry to humans, with no intermediate host involved.

The virus was initially identified in Hong Kong as influenza A, but its subtype could not be determined using standard reagents. By August 1997, the US CDC, the Dutch National Influenza Center in Rotterdam, and the UK's National Institute for Medical Research in London had independently confirmed the virus as H5N1 (per CDC MMWR^※).

According to the Wikipedia biography of Professor Yuen Kwok-yung^※, he was among the first to report the severe clinical presentation of H5N1 in Hong Kong patients in The Lancet, with the paper published in February 1998—one piece of direct evidence of the core clinical and laboratory role played by the HKU team in this event. The HKU microbiology team (including Yuen Kwok-yung, Malik Peiris, and others) has consistently served in this core clinical and laboratory capacity during this event and subsequent avian influenza incidents in Hong Kong.

# 1.2 Containment: The Year-End Cull of Over 1.5 Million Chickens

Per the CDC Museum Digital Exhibits^※, the outbreak was ultimately halted by a territory-wide poultry cull: at the end of December 1997, Hong Kong culled more than 1.5 million chickens and suspended the live poultry trade. This decisive move cut the poultry-to-human transmission chain and is regarded as a critical public health intervention that successfully prevented a wider epidemic.

Background (per academic reviews): The experience of 1997 spurred a series of long-term prevention and control measures for avian influenza in Hong Kong (e.g., rest days for live poultry markets, poultry surveillance, separation of humans and poultry), and established HKU's microbiology and public health teams as key collaborators for international agencies like the WHO on influenza surveillance. This institutional accumulation of expertise would prove its worth again during the 2003 SARS and 2020 COVID-19 outbreaks.

# 1.3 Why 1997 is the "Starting Point"

The 1997 H5N1 event is the foundational starting point on HKU's "emerging infectious diseases flagship" timeline, representing a scientific and institutional "first": scientifically, it was the first time empirical evidence shattered the old paradigm that avian flu needed a pig intermediary to infect humans; institutionally, it thrust Hong Kong—and the HKU team—onto the international influenza surveillance stage for the first time, and laid the scientific and talent foundation for the establishment of the State Key Laboratory of Emerging Infectious Diseases (SKLEID) in 2005 (see hku-named-pathogens.md). Alongside the 2003 SARS, 2009 H1N1, H7N9, MERS, and 2020 COVID-19, it forms part of HKU's sustained, two-decade-plus research output trajectory in emerging infectious diseases.

Note: The delineation of identification tasks among various institutions during the 1997 avian flu event and the specific role of HKU are attributed here based on CDC and academic literature sources. Claims of HKU being "first/exclusive" are adopted only when directly substantiated by official or academic sources. Detailed clinical specifics and the diagnostic timeline of individual cases are summarised in the CID review; original case reports should be consulted for case-by-case details. Cull numbers vary slightly across sources; this text uses the conservative phrasing "more than 1.5 million."

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# II. 2003: Identification of the SARS Coronavirus

# 2.1 Pathogen Identification by the HKU Microbiology Team

During the 2003 outbreak of severe acute respiratory syndrome (SARS), the Department of Microbiology at HKU was among the first teams globally to isolate, identify, and confirm the causative pathogen. According to the HKU "Remembering SARS 2003" page^※, a team led by Professor of Virology Malik Peiris and Head of Microbiology Yuen Kwok-yung (including members Guan Yi, Leo Poon, John Nicholls, Chan Kwok-hung, and others) successfully isolated and cultured the virus responsible for SARS, proved it was a novel coronavirus, and developed an antibody test for it. The team's seminal work was published in The Lancet on 19 April 2003.

# 2.2 Tracing the Animal Origin: Civets and Subsequent Corrections

Once the pathogen was identified, the HKU team further traced the animal origin of the SARS coronavirus. According to a paper led by HKU's Guan Yi and published in Science^※ (2003), a team working in collaboration with the Shenzhen CDC isolated viruses closely related to the human SARS coronavirus from Himalayan palm civets and one raccoon dog in a Guangdong market, suggesting small mammals like the palm civet were significant intermediate hosts.

According to the Wikipedia biography of Professor Yuen Kwok-yung^※, he led a team during the 2003 SARS outbreak that discovered SARS-CoV-1 and traced its genetic origins back to wild bats—this "bat–intermediate host–human" transmission chain became the starting point for extensive subsequent research on the numerous bat coronaviruses bearing the "HKU" designation (see hku-named-pathogens.md).

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# III. From 2020 Onwards: Research Contributions during COVID-19

# 3.1 Early Warnings and Virus Isolation (Early 2020)

During the COVID-19 pandemic, the HKU Faculty of Medicine once again positioned itself at the global research front line. According to HKU Bulletin "HKU's Virus Experts Called to Action"^※ (May 2020) and the Wikipedia biography of Professor Yuen Kwok-yung:

• Professor Yuen Kwok-yung has stated that he warned mainland Chinese health officials on 12 January 2020^※ about the potential for human-to-human transmission (this claim was not made public before 19 January);
• Professor Malik Peiris was one of the first scientists outside mainland China to isolate the virus and, collaborating with Professor John Nicholls from the Department of Pathology, produced early microscopic images of the virus replicating inside cells;
• The HKU Faculty of Medicine developed a hamster animal model that reacts to the virus similarly to humans, providing a crucial platform for research on vaccines, pathogenesis, and treatments;
• Per the same source, the HKU team achieved multiple "firsts" in COVID-19 research, including the first evidence of human-to-human transmission via a family cluster, the first epidemiological report on COVID-19, the first electron microscope images of the virus, and the first potential mathematical model of spread.

Representative scholars involved, as listed in the source, include Yuen Kwok-yung, Malik Peiris, Gabriel Leung, Leo Poon, and John Nicholls, among others.

Regarding the ancestral (Wuhan strain) virus HKU-001a (GenBank: MT230904) isolated by HKU, records are available in public gene banks. This publication only records the fact of its isolation and does not discuss the controversy over the origins of COVID-19.

# 3.2 The First Laboratory-Confirmed Re-infection Case (August 2020)

According to Professor Yuen's Wikipedia biography^※, he was a lead author of a paper published in August 2020 in Clinical Infectious Diseases describing the world's first laboratory-confirmed case of COVID-19 re-infection—using genetic sequencing to prove that the same person could be infected by two different virus strains sequentially, rather than merely having a persisting positive test from the initial infection. This finding had significant implications for understanding the durability of immunity to COVID-19 and for informing vaccine strategies.

# 3.3 The Intranasal COVID-19 Vaccine: From "Vaccine Seed" to Emergency Use on the Mainland

HKU's unique contribution to COVID-19 vaccines is an intranasal COVID-19 vaccine based on a DelNS1 live attenuated influenza virus (LAIV) platform. According to information from HKU's Department of Microbiology and the Centre for Virology, Vaccinology and Therapeutics (CVVT)^※, the team created the vaccine seed as early as February 2020, which provided protection in the hamster model.

This vaccine utilises a highly attenuated influenza virus genome, expressing the COVID-19 receptor-binding domain (RBD) at the site where the NS1 gene is deleted, while retaining the key influenza virus antigens. Development was completed through a collaboration between HKU, Xiamen University, and Wantai BioPharm. According to an official HKU press release dated 5 December 2022^※, the vaccine was approved for emergency use in mainland China by the National Medical Products Administration (NMPA) on 5 December 2022. Phase III data released by HKU showed high protection against hospitalisation and severe illness, with efficacy against Omicron exceeding 80% among those already vaccinated. According to multiple reports, the research team was led by Professor Honglin Chen, with members including Zhiwei Chen, Ivan Hung, and Yuen Kwok-yung.

The principle behind it is this: injectable vaccines induce systemic immunity in the blood but offer limited protection at the nasal and throat mucosa—the primary site of viral entry. An intranasal vaccine establishes mucosal immunity right at this entry portal, and it removes the need for a needle injection.

Continuing with this same technology platform, the State Key Laboratory of Emerging Infectious Diseases (HKU) and the InnoHK "Centre for Virology, Vaccinology and Therapeutics (CVVT)" subsequently developed a nasal spray H5N1 avian influenza vaccine (2025, see details in hku-named-pathogens.md), extending the advantage of the DelNS1 platform in achieving respiratory mucosal immunity.

# 3.4 From "Diagnosticians" to "Sentinel Warners and Tool Developers"

The 2020 COVID-19 pandemic is the latest chapter in the timeline of HKU's "emerging infectious diseases flagship." It once again validated the integrated "clinical–laboratory–vaccine" response capacity, and extended HKU's output from "pathogen identification" (as in SARS) into "re-infection mechanisms" and "vaccine development." HKU's role in COVID-19 was similar to its role in SARS, yet also represented a progression. The similarity lies in the proven effectiveness of the "sentinel rapid-response" model. The progression lies in the increased depth of the output: during SARS, HKU's most prominent contribution was "recognising the virus"; by the time of COVID-19, the output had extended in both directions—upstream towards "early warning" and downstream towards "intervention tools" (elucidating re-infection mechanisms, developing the intranasal vaccine right through to its approval for use). This depth of reach is a hallmark of a university's research capacity maturing from "isolated breakthroughs" to "systematic output."

Unverified/Awaiting confirmation: This article relays the account of the specific "early warning" event in January 2020 based on the interview statements recorded in Professor Yuen's biography. The complete timeline and the records from various parties involved have differing narratives; this article only attributes the statement to its source and does not make a ruling on the events. Phase-specific clinical data for the intranasal vaccine vary depending on the research stage and population; precise figures should be verified against peer-reviewed papers. The names of team members, as stated, are based on official announcements and paper authorship.

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# IV. The Epidemiology Track: The School of Public Health and the WHO Collaborating Centre

HKU's strength in "emerging infectious diseases" is built upon two complementary tracks: the laboratory side (microbiology/virology—isolating pathogens and developing vaccines, see above and hku-named-pathogens.md); and the population side (epidemiology/public health—studying transmission dynamics and prevention/control). For the institutional overview of the School of Public Health, see ../11-medical-hospital/school-of-public-health-and-chinese-medicine.md.

# 4.1 WHO Collaborating Centre: HKU's First (2014)

According to the official page of the School of Public Health, HKU^※, the School (under the Li Ka Shing Faculty of Medicine) was designated as the "WHO Collaborating Centre for Infectious Disease Epidemiology and Control" by the World Health Organization (WHO) on 19 December 2014. This was HKU's first WHO Collaborating Centre of its kind, signifying formal international recognition of its epidemiological research.

# 4.2 Research Strengths: Beyond the Virus Itself

Unlike the laboratory side's focus on "isolating pathogens and developing vaccines," the School of Public Health focuses on how diseases spread through populations and how to control them. According to its official page, its research and teaching cover the epidemiology of influenza and other emerging viruses, control of both communicable and non-communicable (chronic) diseases, tobacco control, and air pollution, as well as behavioural science, exercise science, life course epidemiology, health economics, and health services management.

Background: Placing the "laboratory" and "population" tracks side-by-side provides a complete explanation for why HKU has been able to both "identify the virus" and "articulate how to stop it" during successive epidemics. During SARS and COVID-19, HKU had both the microbiology teams isolating the pathogen and the public health teams evaluating countermeasures—the two tracks reinforcing each other.

# 4.3 COVID-19 2020: Studying Containment "Without a Complete Lockdown"

One of the most internationally noted outputs from the HKU School of Public Health during the COVID-19 pandemic was its epidemiological assessment of Hong Kong's containment model. According to a 2020 announcement from the School of Public Health^※, the team studied how Hong Kong managed and controlled its first wave of the epidemic without resorting to a complete lockdown. According to the relevant academic paper^※, the team systematically evaluated the impact of non-pharmaceutical interventions (NPIs)—such as social distancing, mask-wearing, and school closures—on the transmission of both COVID-19 and influenza. This type of "intervention effectiveness" research provided an empirical reference from Hong Kong for global policymaking during the pandemic.

Unverified/Awaiting confirmation: The annual output since the Centre's founding is summarised here based on its official page and representative studies; for a complete list of outputs, refer to the official pages of the School of Public Health and the Centre. The names of key scholars are based on the School's official pages. The specific numerical conclusions from NPI studies vary across different papers depending on the data and period analysed; precise figures should be verified against the peer-reviewed literature.

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# V. Summary and "Unverified" Items

• Securely Sourced: The first human H5N1 infection in 1997 (CDC/academic), the identification of the SARS coronavirus in 2003 (The Lancet), tracing SARS to civets (Science), COVID-19 virus isolation and the intranasal vaccine, and the WHO Collaborating Centre for Infectious Disease Epidemiology and Control (2014) are all supported by official or academic sources.
• Proactively Sought Counter-Evidence and Precision: "Who was the absolute first" for SARS (multiple teams near-simultaneously), "whether civets are the definitive source" (subsequent evidence points to bats), and the "world's first intranasal COVID-19 vaccine" claim (attributed to the media, not an HKU definitive statement) have all been addressed.
• Unverified / Not Expanded Upon: This article does not touch upon the origins of COVID-19 (a matter beyond the scope of research breakthroughs and highly politicised).
• Cross-References: For laboratories and research platforms (SKLEID, HKU-Pasteur, InnoHK), representative scholars and international honours, and pathogens named with the "HKU" designation, see hku-named-pathogens.md. For other breakthroughs like living donor liver transplantation, see liver-transplant-breakthroughs.md. For the State Key Laboratories structure, see institutes-and-labs.md. For the Faculty of Medicine and Queen Mary Hospital, see ../11-medical-hospital/.

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