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

The death of a three-year-old boy. A novel coronavirus that two international laboratories reportedly "had to revise their sequences to match". A vaccine that bet on a nasal spray rather than a needle. In the past three decades, Hong Kong University's microbiology and public health teams have been pushed three times to the front line of global responses to emerging infectious diseases. This article traces, in chronological order, HKU's specific scientific contributions across these three outbreaks, and fact-checks claims such as "world first", actively seeking counter-evidence. Historical, deceased or award-winning scientists are named according to this museum's house style (neutral factual zone, items 00–12).

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

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# 1. 1997: H5N1 avian flu and the "cull-the-chickens" containment

# 1.1 The first case: a three-year-old boy

In 1997, Hong Kong recorded the world's first confirmed human infection with highly pathogenic H5N1 avian influenza. According to the US CDC Museum digital exhibition^※ and a Clinical Infectious Diseases review^※, a three-year-old boy died of a respiratory illness in May 1997, and testing confirmed an infection with influenza A(H5N1) — the first known human case caused by this virus. A further cluster of cases followed in November–December of that year, bringing the year's total to 18 confirmed cases and 6 deaths. Transmission was directly from chickens to humans, with no intermediate host involved.

The virus was initially identified in Hong Kong as an influenza A virus, but its subtype could not be determined with standard reagents. By August 1997, the US CDC, the Dutch National Influenza Centre 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 Yuen Kwok-yung^※, he was the first to report the severe clinical presentation of H5N1 in Hong Kong patients, in The Lancet, with the paper published in February 1998 — direct evidence of the HKU team's central clinical and laboratory role in this episode. The HKU microbiology team (Yuen Kwok-yung, Malik Peiris and others) continued to play a central clinical and laboratory role in this event and in Hong Kong's subsequent avian influenza incidents.

# 1.2 Containment: culling over 1.5 million chickens in late December

According to the CDC Museum digital exhibition^※, the outbreak was ultimately contained by a territory-wide poultry cull: in late December 1997, Hong Kong culled more than 1.5 million chickens and suspended the live poultry trade. This decisive measure broke the bird-to-human transmission chain and is regarded as the key public health intervention that prevented the outbreak from spreading further.

Background (based on academic reviews): The 1997 experience gave rise to a series of long-term avian influenza control measures in Hong Kong — the market rest-day system for live poultry, poultry surveillance, separation of people from poultry, and so on — and made HKU's microbiology and public health teams important collaborators for the WHO and other international bodies in influenza surveillance. This institutional accumulation would prove its worth again in the 2003 SARS outbreak and the 2020 COVID-19 pandemic.

# 1.3 Why 1997 is the "starting point"

The 1997 H5N1 episode is the initiating event on the timeline of HKU's flagship strength in emerging infectious diseases — a "first" on both the scientific and the institutional level. Scientifically, it was the first empirical demonstration that the old paradigm — "avian flu must pass through pigs before it can infect humans" — was wrong. Institutionally, it pushed Hong Kong (and the HKU team) onto the front stage of international influenza surveillance for the first time, and built the scientific and human capital that led to the establishment of the State Key Laboratory of Emerging Infectious Diseases (SKLEID) in 2005 (see hku-named-pathogens.md). Together with 2003 SARS, 2009 H1N1, H7N9, MERS and COVID-19, it forms part of a continuous output stream in emerging infectious diseases spanning more than two decades.

Note: for the division of identification work among institutions in the 1997 avian flu episode and HKU's specific role, this museum follows CDC and academic literature attributions; claims that HKU was "first" or "exclusive" are adopted only where directly supported by official or academic sources. The Clinical Infectious Diseases review summarises the clinical details and diagnostic timelines of individual cases; case-by-case detail requires consulting the original case reports. Figures for the number of poultry culled vary slightly between sources; this article adopts the conservative "over 1.5 million" figure.

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# 2. 2003: Identifying the SARS coronavirus

# 2.1 The HKU microbiology team identifies the pathogen

During the 2003 severe acute respiratory syndrome (SARS) outbreak, the Department of Microbiology at HKU was among the first teams in the world to isolate, identify and confirm the causative pathogen. According to the HKU "Remembering SARS 2003" web page^※, the team led by Professor Malik Peiris, head of virology, and Professor Yuen Kwok-yung, head of microbiology (with members including Guan Yi, Leo Poon, John Nicholls and Chan Kwok-hung), succeeded in isolating and culturing the virus that caused SARS, demonstrated that it was a novel coronavirus, and developed antibody detection methods. The team's pioneering work was published in The Lancet on 19 April 2003.

# 2.2 Tracing the animal origin: civets and later corrections

Once the pathogen was identified, the HKU team went on to trace the animal origin of the SARS coronavirus. According to a paper by Guan Yi et al. published in Science^※ (2003), the team led by HKU's Guan Yi, collaborating with the Shenzhen CDC, isolated viruses closely related to the human SARS coronavirus from Himalayan palm civets and a raccoon dog at a market in Guangdong, indicating that civets and other small mammals were important intermediate hosts.

According to the Wikipedia biography of Yuen Kwok-yung^※, he led his team during the 2003 SARS outbreak in discovering SARS-CoV-1 and tracing its genetic origin to wild bats — a "bat–intermediate host–human" line of inquiry that became the starting point for the large body of "HKU-numbered" bat coronavirus research that followed (see hku-named-pathogens.md).

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# 3. From 2020 onwards: research contributions to COVID-19

# 3.1 Early warnings and virus isolation (early 2020)

During the COVID-19 pandemic, the HKU medical school was again at one of the world's research front lines. According to the HKU Bulletin article "HKU's Virus Experts Called to Action"^※ (May 2020) and the Wikipedia biography of Yuen Kwok-yung:

• Yuen Kwok-yung has said that on 12 January 2020 he alerted mainland Chinese health officials^※ to the possibility of human-to-human transmission (this claim was not made public before 19 January);
• Professor Malik Peiris was among the first scientists outside mainland China to isolate the virus, and worked with Professor John Nicholls of the Department of Pathology to produce early microscope images of the virus replicating inside cells;
• The HKU medical school developed a hamster animal model that responds to the virus similarly to humans, providing a key platform for vaccine, pathogenesis and therapy research;
• According to the same page, the HKU team achieved a number of "firsts" in COVID-19 research, including the first evidence of household clusters of human-to-human transmission, the first epidemiological report on COVID-19, the first electron microscope images of the virus, and the first mathematical model of potential spread.

Representative scholars named on the page include Yuen Kwok-yung, Malik Peiris, Gabriel Leung, Leo Poon and John Nicholls.

On the prototype (Wuhan strain) virus isolate HKU-001a (GenBank: MT230904) that HKU isolated, see the public sequence database record; this museum merely records the fact of isolation and does not enter into the debate over COVID-19's origins.

# 3.2 The first laboratory-confirmed case of reinfection (August 2020)

According to the Wikipedia biography of Yuen Kwok-yung^※, he was a lead author on a paper published in Clinical Infectious Diseases in August 2020 describing the world's first laboratory-confirmed case of COVID-19 reinfection — using genetic sequencing to prove that the same person had been infected sequentially by two different virus strains, rather than simply testing positive again. The finding had important implications for understanding immune persistence and vaccine strategy for COVID-19.

# 3.3 The intranasal COVID-19 vaccine: from "vaccine seed" to emergency use in mainland China

HKU's distinctive contribution to COVID-19 vaccines was an intranasal COVID-19 vaccine built on a delNS1 live attenuated influenza virus (LAIV) platform. According to materials from the HKU Department of Microbiology and the Centre for Virology, Vaccinology and Therapeutics (CVVT)^※, the team had already produced the vaccine seed in February 2020, and it provided protection in the hamster model.

The vaccine uses a highly attenuated influenza virus genome, with the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein expressed at the site where the NS1 gene has been deleted, while retaining key influenza vaccine antigens. Development was carried out by HKU in collaboration with Xiamen University and Wantai BioPharm. According to an official HKU announcement of 5 December 2022^※, on 5 December 2022 the vaccine received approval from China's National Medical Products Administration (NMPA) for emergency use in mainland China; HKU's published Phase III data showed high protection against hospitalisation/severe disease and over 80% efficacy against Omicron in people 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 rationale: injectable vaccines induce systemic immunity in the blood, but offer limited protection at the mucosa of the nose and throat — the virus's first port of entry. An intranasal vaccine establishes mucosal immunity directly at the site of entry, and requires no needle.

Extending the same technology platform, the State Key Laboratory of Emerging Infectious Diseases and the InnoHK Centre for Virology, Vaccinology and Therapeutics (CVVT) subsequently developed an intranasal H5N1 avian influenza vaccine (2025; see hku-named-pathogens.md), building on the delNS1 platform's advantage in respiratory mucosal immunity.

# 3.4 From "diagnostician" to "early-warner + tool-developer"

COVID-19 is the latest link in the timeline of HKU's flagship strength in emerging infectious diseases: it validated once again HKU's integrated "clinical–laboratory–vaccine" response capability, and extended HKU's output from "pathogen identification" (SARS) to "reinfection mechanisms" and "vaccine development". HKU's role in COVID-19 was both similar to and an advance on its role in SARS — similar in that the "sentinel–rapid response" model worked again; advanced in the "depth" of output: in SARS, HKU's most prominent contribution was "recognising the virus"; in COVID-19, output extended in both directions — upstream towards "early warning" and downstream towards "intervention tools" (elucidating reinfection mechanisms, developing an intranasal vaccine through to regulatory approval). This depth marks the evolution of a university's research capability from "single-point breakthrough" to "systematised output".

Unverified/pending: on the specific course of the January 2020 "early warning", this article relays Yuen Kwok-yung's account as reported in his biography; different narratives of the full timeline and of the various parties' records exist, and this article only attributes the claim to its source without adjudicating. The phase-by-phase clinical data for the intranasal vaccine vary with study stage and population; precise figures should be taken from peer-reviewed papers. Named team members follow official announcements and paper author lists.

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# 4. The epidemiology line: the School of Public Health and the WHO Collaborating Centre

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

# 4.1 The WHO Collaborating Centre: HKU's first such centre (2014)

According to the official web page of the HKU School of Public Health^※, the School (within the Li Ka Shing Faculty of Medicine) has been designated by the World Health Organization (WHO) as a "WHO Collaborating Centre for Infectious Disease Epidemiology and Control" since 19 December 2014 — HKU's first WHO Collaborating Centre of this kind, marking formal international recognition of its epidemiological research by an authoritative international body.

# 4.2 Research strengths: more than the virus itself

Unlike the laboratory side's "isolate the pathogen, develop the vaccine", the School of Public Health focuses on how disease spreads through populations and how it can be controlled. According to the official page, its research and teaching span the epidemiology of influenza and other emerging viruses, control of infectious and non-infectious (chronic) diseases, tobacco control and air pollution, as well as behavioural science, exercise science, life-course epidemiology, health economics and health services management.

Background: Only by putting the "laboratory" and "population" strands together does one fully understand why HKU has been able, in successive outbreaks, both to "recognise the virus" and to "explain how to prevent it". In SARS and COVID-19, HKU had both a microbiology team isolating the pathogen and a public health team evaluating interventions — the two strands supported each other.

# 4.3 COVID-19: studying control without a full lockdown

One of the most internationally noted outputs of the School of Public Health during COVID-19 was its epidemiological assessment of Hong Kong's response model. According to a School of Public Health announcement from 2020^※, the team studied how Hong Kong managed to control the first wave of the pandemic without resorting to a complete lockdown; according to the related academic paper^※, the team systematically assessed the impact of non-pharmaceutical interventions (NPIs) — such as social distancing, mask-wearing and school closures — on the transmission of COVID-19 and influenza. This kind of "intervention effectiveness" research provided empirical reference points from Hong Kong for policy-making during a global pandemic.

Unverified/pending: on the centre's year-by-year output since its establishment, this article gives an overview based on the official page and representative studies; the full list of outputs is on the School's and the Centre's official pages. Named key scholars follow the School's official page. The specific numerical conclusions of the NPI studies vary across papers with data and time periods; precise figures should be taken from the peer-reviewed papers.

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# 5. Summary and unverified items

• Well-sourced: 1997 first human H5N1 case (CDC/academic), identification of the SARS coronavirus (2003, The Lancet), civet source-tracing (Science), isolation of SARS-CoV-2 and the intranasal vaccine, and the WHO Collaborating Centre for Infectious Disease Epidemiology and Control (2014) — all supported by official or academic sources.
• Counter-evidence sought and claims refined: SARS "who was absolutely first" (multiple teams near-simultaneous), whether civets were the "ultimate origin" (later evidence pointed to bats), and the intranasal vaccine as "world first" (attributed to the media, not as an HKU conclusion).
• Unverified / not covered: this article does not enter into the debate over COVID-19 origins (beyond the scope of scientific breakthroughs, and highly politicised).
• Cross-references: laboratories and research platforms (SKLEID, HKU-Pasteur, InnoHK), representative scholars and international honours, and pathogens named after "HKU", see hku-named-pathogens.md; other breakthroughs such as live-donor liver transplantation, see liver-transplant-breakthroughs.md; the architecture of the State Key Laboratories, see institutes-and-labs.md; the medical school and Queen Mary Hospital, see ../11-medical-hospital/.

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