Sheena Sullivan

University of California, Los Angeles | UCLA · Department of Epidemiology

Background: In Australia, seasonal inactivated influenza vaccine is typically offered in April. However, the onset, peak and end of a typical influenza season vary, and optimal timing for vaccination remains unclear. Here, we investigated vaccine-induced antibody response kinetics over 6 months in different age groups. Methods: We conducted a pr...

Ambient particulate matter (PM2.5) is an important component of natural and human-generated air pollution and a major contributor to the global burden of disease. Short-term effects of PM2.5 exposure on respiratory illness have been described but most evidence arises from high pollution settings. We used case-crossover methods to estimate effects o...

Objectives: To assess associations between SARS-CoV-2 infection and the incidence of hospitalisation with selected respiratory and non-respiratory conditions in a largely SARS-CoV-2 vaccine-naïve population . Design, setting, participants: Self-control case series; analysis of population-wide surveillance and administrative data for all laborato...

Background Influenza vaccines require annual readministration; however, several reports have suggested that repeated vaccination might attenuate the vaccine's effectiveness. We aimed to estimate the reduction in vaccine effectiveness associated with repeated influenza vaccination. Methods In this systematic review and meta-analysis, we searched ME...

Background Influenza circulated at historically-low levels during 2020 and 2021 due to COVID-19 pandemic travel restrictions. In Australia, international arrivals to Australia were required to undertake 14 days hotel quarantine to limit new introduction of SARS-CoV-2 virus. Methods We used routine testing data for travellers arriving on repatriati...

Background Hong Kong has enforced stringent travel restrictions particularly for inbound travellers since the emergence of SARS-CoV-2. Understanding the characteristics of imported COVID-19 cases is important for establishing evidence-based control measures. Methods We conducted a retrospective cohort study to summarise the characteristics of case...

Human respiratory syncytial virus (RSV) is an important cause of acute respiratory infection with the most severe disease in the young and elderly. Non-pharmaceutical interventions and travel restrictions for controlling COVID-19 have impacted the circulation of most respiratory viruses including RSV globally, particularly in Australia, where durin...

Responses to the early (February–July 2020) COVID-19 pandemic varied widely, globally. Reasons for this are multiple but likely relate to the healthcare and financial resources then available, and the degree of trust in, and economic support provided by, national governments. Cultural factors also affected how different populations reacted to the v...

Annual epidemics of seasonal influenza cause hundreds of thousands of deaths, high levels of morbidity, and substantial economic loss. Yet, global influenza circulation has been heavily suppressed by public health measures and travel restrictions since the onset of the COVID-19 pandemic. Notably, the influenza B/Yamagata lineage has not been conclu...

Prior vaccination can alternately enhance or attenuate influenza vaccine immunogenicity and effectiveness. Analogously, we found that vaccine immunogenicity was enhanced by prior A(H3N2) virus infection among participants of the Ha Nam Cohort, Viet Nam, but was attenuated by prior vaccination among Australian Health Care Workers (HCWs) vaccinated i...

Background: When new vaccine components or platforms are developed, they will typically need to demonstrate non-inferiority or superiority over existing products, resulting in the assessment of relative vaccine effectiveness (rVE). This review aims to identify how rVE evaluation is being performed in studies of influenza to inform a more standardi...

Studies of successive vaccination suggest that immunological memory against past influenza viruses may limit responses to vaccines containing current strains. The impact of memory induced by prior infection is rarely considered and is difficult to ascertain, because infections are often subclinical. This study investigated influenza vaccination amo...

Background: Large-scale evaluation of COVID-19 is likely to rely on the quality of ICD coding. However, little is known about the validity of ICD-coded COVID-19 diagnoses. Objectives: To evaluate the performance of diagnostic codes in detecting COVID-19 during pregnancy. Methods: We used data from a national cohort of 78,283 individuals with a...

A key aim of serosurveillance during the COVID-19 pandemic has been to estimate the prevalence of prior infection, by correcting crude seroprevalence against estimated test performance for PCR-confirmed COVID-19. We show that poor generalisability of sensitivity estimates to some target populations may lead to substantial underestimation of case nu...

Background SARS-CoV-2 infection has been associated with increased risk of adverse perinatal health outcomes. However, few large-scale, community-based epidemiological studies have been conducted. Methods We conducted a national cohort study using de-identified administrative claims data for 78,283 pregnancies with estimated conception before 30 A...

During the coronavirus disease pandemic, international travel controls have been widely adopted. To determine the effectiveness of these measures, we analyzed data from 165 countries and found that early implementation of international travel controls led to a mean delay of 5 weeks in the first epidemic peak of cases.

Background: Hospital-based contact tracing aims to limit spread of COVID-19 within healthcare facilities. In large outbreaks, this can stretch resources and workforce due to quarantine of uninfected staff. We analysed the performance of a manual contact tracing system for healthcare workers (HCW) at a multi-site healthcare facility in Melbourne, A...

Annual epidemics of seasonal influenza cause hundreds of thousands of deaths, high levels of morbidity, and substantial economic loss. Yet, global influenza circulation has been heavily suppressed by public health measures and travel restrictions since the onset of the COVID-19 pandemic. Notably, the influenza B/Yamagata lineage has not been conclu...

Background Many countries/regions implemented strict border measures (e.g., 14-day quarantines) as a blanket policy to prevent COVID-19 importations, while proposed “travel bubbles” as an alternative to reduce the impact of border controls. We aim to examine the differential importation risks with departure origins and post-arrival controls. Metho...

Background Influenza is the most common vaccine-preventable disease in Australia, causing significant morbidity and mortality. We assessed the burden of influenza across all ages in terms of influenza-associated mortality and hospitalizations using national mortality, hospital-discharge and influenza surveillance data. Methods Influenza-associated...

Human respiratory syncytial virus (RSV) is an important cause of acute respiratory infection (ARI) with the most severe disease in the young and elderly. Non-pharmaceutical interventions (NPIs) and travel restrictions for controlling COVID-19 have impacted the circulation of most respiratory viruses including RSV globally, particularly in Australia...

Background and Aims Influenza vaccination is recommended by the World Health Organisation for pregnant women, offering the dual benefit of protecting pregnant women and their newborn infants against influenza infection. Various factors can influence vaccine immunogenicity, with obesity being one factor implicated in varied responses. This study aim...

Background: Mongolia is a vast, sparsely populated country in central Asia. Its harsh climate and nomadic lifestyle make the population vulnerable to acute respiratory infections, particularly influenza. Evidence on the morbidity, mortality and socioeconomic impact of influenza in Mongolia is scarce; however, routine surveillance for influenza-like...

Background: Mongolia is a vast, sparsely populated country in central Asia. Its harsh climate and nomadic lifestyle make the population vulnerable to acute respiratory infections, particularly influenza. Evidence on the morbidity, mortality and socioeconomic impact of influenza in Mongolia is scarce; however, routine surveillance for influenza-lik...

Background There was an acute outbreak of vanA Enterococcus faecium (VREfm) in a tertiary Melbourne teaching hospital between 2015 and 2016 amongst Cardiothoracic Surgery (CTS) ward and Intensive Care Unit (ICU) patients. Prior to this outbreak vanB VRE had been the predominate genotype encountered. Methods A retrospective, matched (1:2), case–con...

Background Serological testing for SARS-CoV-2 complements nucleic acid tests for patient diagnosis and enables monitoring of population susceptibility to inform the COVID-19 pandemic response. It is important to understand the reliability of assays with different antigen or antibody targets to detect humoral immunity after SARS-CoV-2 infection and...

Background Epidemiological studies suggest that influenza vaccine effectiveness decreases with repeated administration. We examined antibody responses to influenza vaccination among healthcare workers (HCWs) by prior vaccination history and determined the incidence of influenza infection. Methods HCWs were vaccinated with the 2016 Southern Hemisph...

Test-negative studies are commonly used to estimate influenza vaccine effectiveness (VE). In a typical study, an “overall VE” estimate may be reported based on data from the entire sample. However, there may be heterogeneity in VE, particularly by age. We therefore discuss the potential for a weighted average of age-specific VE estimates to provide...

Many viruses cause seasonal respiratory infections in temperate climates that peak in the winter months. They cause varying degrees of respiratory illness across all age groups, and include respiratory syncytial virus (RSV), parainfluenza viruses (types 1‐4), human metapneumovirus, rhinoviruses, seasonal coronaviruses (OC43, 229E, NL63, HKU1), ente...

Background: Serological testing for SARS-CoV-2 complements nucleic acid tests for patient diagnosis and enables monitoring of population susceptibility to inform the COVID-19 pandemic response. As we move into the era of vaccines, the detection of neutralising antibody will become increasingly important. Many serological tests have been developed u...

The coronavirus disease pandemic was declared in March 2020, as the southern hemisphere’s winter approached. Australia expected co-circulation of severe acute respiratory syndrome coronavirus 2, influenza and other seasonal respiratory viruses. However, influenza notifications were 7,029 (March–September) compared with an average 149,832 for the sa...

Background Seroprotection and seroconversion rates are not well understood for 2-dose inactivated influenza vaccination (IIV) schedules in autologous haematopoietic stem cell transplantation (autoHCT) patients. Materials/methods A randomised single-blind controlled trial of IIV in autoHCT patients in their first year post-transplant was conducted....

In 2018, a 15-year-old female adolescent in Australia was infected with swine influenza A(H3N2) variant virus. The virus contained hemagglutinin and neuraminidase genes derived from 1990s-like human seasonal viruses and internal protein genes from influenza A(H1N1)pdm09 virus, highlighting the potential risk that swine influenza A virus poses to hu...

In 2018, a 15-year-old female adolescent in Australia was infected with swine influenza A(H3N2) variant virus. The virus contained hemagglutinin and neuraminidase genes derived from 1990s-like human seasonal viruses and internal protein genes from influenza A(H1N1)pdm09 virus, highlighting the potential risk that swine influenza A virus poses to hu...

We compared 2019 influenza seasonality and vaccine effectiveness (VE) in four southern hemisphere countries: Australia, Chile, New Zealand and South Africa. Influenza seasons differed in timing, duration, intensity and predominant circulating viruses. VE estimates were also heterogeneous, with all-ages point estimates ranging from 7-70% (I2: 33%) f...

Background Interseasonal influenza outbreaks are not unusual in countries with temperate climates and well-defined influenza seasons. Usually, these are small and diminish before the main influenza season begins. However, the 2018/19 summer-autumn interseasonal influenza period in Australia saw unprecedented large and widespread influenza outbreaks...

Self-collected nasal swabs offer a cheaper alternative to professional-collected swabs for influenza testing. However, the diagnostic accuracy of self-collection has not been quantitatively reviewed. We identified 14 studies that compared diagnostic accuracy of self-collected to professional-collected swabs in influenza symptomatic individuals. Sel...

Background: The precision of vaccine effectiveness (VE) estimates is dependent on sample size and sampling methods. In Victoria, participating general practitioners (GPs) are not limited by the number of influenza-like illness (ILI) patients they collect respiratory samples (swabs) from in sentinel surveillance. However, in the context of scarce r...

Background We estimated the effectiveness of seasonal inactivated influenza vaccine and the potential influence of timing of immunization on vaccine effectiveness (VE) using data from the 2016 southern hemisphere influenza season. Methods Data were pooled from three routine syndromic sentinel surveillance systems in general practices in Australia....

Vaccination is the most practical means available for preventing influenza. Influenza vaccines require frequent updates to keep pace with antigenic drift of the virus, and the effectiveness, and sometimes the safety, of the vaccine can therefore vary from season to season. Three key populations that the World Health Organization recommends should b...

Background: The protection conferred by influenza vaccination is generally thought to last less than a year, necessitating annual revaccination. However, the speed with which influenza vaccine effectiveness might decline during a year is unknown, which is of particular importance for locations with year-round influenza activity. We aimed to assess...

The continuous improvement in laboratory capacity for influenza surveillance has helped drive the development of diagnostic and virology laboratories in the Global Influenza Surveillance and Response System (GISRS) in the Western Pacific Region, at the same time strengthening their ability to detect and respond to infectious threats beyond influenz...

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The factors that determine the pattern and rate of spread of influenza virus at a continental-scale are uncertain. Although recent work suggests that influenza epidemics in the United States exhibit a strong geographical correlation, the spatiotemporal dynamics of influenza in Australia, a country and continent of approximately similar size and cli...

Summary of the data set. The number of laboratory-confirmed influenza cases in Australia, per day, from 1st January 2006 until 31st December 2016, showing (A) patient age ranges; and (B) the type/subtype of the virus detected. (TIF)

The order of grey vertical bars in Fig 4 in the main text that mark the pairwise distances between the major cities. (DOCX)

(A) The mean (and 95% confidence intervals) week of epidemic onset timing for influenza A (both subtypes and unsubtyped data) and B in Australia. (B) The mean (and 95% confidence intervals) week of epidemic onset timing for influenza A/H1N1, A/H3N2 and B. (TIF)

Maximum likelihood phylogenetic trees of influenza virus, showing the two largest clades isolated from Australia that had specific sampling location available from each year shown in Fig 6 in the main text (A-B: A/H1N1 2009; C-D: A/H3N2 2014; E-F: influenza B 2015). HA genetic sequences were downloaded from the GISAID EpiFlu database (platform.gisa...

For over a decade virtually all A(H3N2) influenza viruses have been resistant to the adamantane class of antivirals. However, during the 2017 influenza season in Australia, 15/461 (3.3%) adamantane-sensitive A(H3N2) viruses encoding serine at residue 31 of the M2 protein were detected, more than the total number identified globally during the last...

Influenza viruses are associated with substantial global burden of morbidity and mortality every year. Estimates of influenza-associated mortality often vary between studies due to differences in study settings, methods and measurement of outcomes. We reviewed 103 published articles assessing population-based influenza-associated mortality through...

One important assumption in case-control studies is that control selection should be independent of exposure. Nevertheless, it has been hypothesized that virus interference might lead to a correlation between receipt of influenza vaccination and increased risk of infection with other respiratory viruses. We investigated if such a phenomenon might a...

Objective We aimed to describe the theoretical basis and the potentialapplications of the test-negative design for estimating influenzavaccination effectiveness in sentinel influenza surveillance.IntroductionThe test-negative design is a variation of the case-control study,in which patients are enrolled in outpatient clinics (and/or hospitals)based...

Influenza B viruses make up an important part of the burden from seasonal influenza globally. The 2015 sea-son in Australia saw an unusual predominance of influ-enza B with a distinctive switch during the season from B/Yamagata/16/88 lineage viruses to B/Victoria/2/87 lineage viruses. We also noted significant differences in the age groups infected...

The WHO Collaborating Centre for Reference and Research on Influenza in Melbourne is part of the World Health Organization's (WHO) Global Influenza Surveillance and Response System. In 2014 the Centre received a total of 5,374 influenza samples from laboratories primarily in the Asia-Pacific region. Viruses were characterised by their antigenic, ge...

Influenza vaccination is the most practical means available for preventing influenza virus infection and is widely used in many countries. Because vaccine components and circulating strains frequently change, it is important to continually monitor vaccine effectiveness (VE). The test-negative design is frequently used to estimate VE. In this design...

We have been reading with interest the recent reports of interim estimates of influenza vaccine effectiveness (VE) for the 2014/2015 northern hemisphere season.1–4 The test-negative design has now become established as the standard observational design for timely assessment of influenza VE.5 Studies following this design often report both a crude a...

The factors that determine the characteristic seasonality of influenza remain enigmatic. Current models predict that occurrences of influenza outside the normal surveillance season within a temperate region largely reflect the importation of viruses from the alternate hemisphere or from equatorial regions in Asia. To help reveal the drivers of seas...

The burden of disease due to influenza B is often underestimated. Clinical studies have shown that oseltamivir, a widely used neuraminidase inhibitor (NAI) antiviral drug, may have reduced effectiveness against influenza B viruses. Therefore, it is important to study the effect of neuraminidase mutations in influenza B viruses that may further redu...

AimsTo describe the data collected by the Chinese methadone maintenance treatment (MMT) system and the characteristics of clients entering the programme.DesignDescriptive study using routinely collected data from the MMT data management system for the period March 2004 and March 2010.SettingAll MMT clinics in China.ParticipantsClients who enrolled...

The influenza virus undergoes frequent antigenic drift, necessitating annual review of the composition of the influenza vaccine. Vaccination is an important strategy for reducing the impact and burden of influenza, and estimating vaccine effectiveness (VE) each year informs surveillance and preventative measures. We aimed to describe the influenza...

Background: The test-negative design is a variant of the case-control study being increasingly used to study influenza vaccine effectiveness (VE). In these studies, patients with influenza-like illness are tested for influenza. Vaccine coverage is compared between those testing positive versus those testing negative to estimate VE. Objectives: W...

During 2010-2012 the strain composition of the influenza vaccine in the Southern Hemisphere did not change, but the circulating virus type/subtype did. We pooled data for these years from the Western Australian sentinel medical practice surveillance system for influenza to estimate vaccine effectiveness (VE) by influenza virus type and subtype. A c...

Objective: To estimate influenza vaccine coverage and effectiveness against medically attended laboratory-confirmed influenza for the 2012 season. Design, setting and participants: Test-negative design involving patients recruited as part of the Australian Sentinel Practices Research Network, a network of sentinel general practitioners throughou...

Vaccine effectiveness may wane with increasing time since vaccination. This analysis used the Victorian sentinel general practitioner (GP) network to estimate vaccine effectiveness for trivalent inactivated vaccines in the 2012 season. A test-negative design was used where patients presenting to GPs with influenza-like illness who tested positive f...

Objectives The emergence of the pandemic influenza A(H1N1)pdm09 virus in 2009 saw a significant increase in the therapeutic and prophylactic use of neuraminidase inhibitors (NAIs) to mitigate the impact of this highly transmissible virus. Prior to the pandemic, many countries stockpiled NAIs and developed pandemic plans for the use of antiviral dru...

Influenza viruses collected from regions of Asia, Africa and Oceania between 2009 and 2012 were tested for their susceptibility to two new neuraminidase inhibitors, peramivir and laninamivir. All viruses tested had normal laninamivir inhibition. However, 3·2% (19/599) of A(H1N1)pdm09 viruses had highly reduced peramivir inhibition (due to H275Y NA...

Background Methadone maintenance treatment (MMT) in China was established in 2004. The purpose of the present study was to estimate client retention and identify client factors associated with longer times in treatment. Methods Data were abstracted from the MMT Data System from April 2008 to March 2010. Clients were considered to have interrupted...

To assess the magnitude and severity of the 2012 influenza season in Victoria, Australia using surveillance data from five sources. Data from influenza notifications, sentinel general practices, a sentinel hospital network, a sentinel locum service and strain typing databases for 2012 were descriptively analysed. Influenza and influenza-like illnes...