Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 during Border Quarantine and Air Travel, New Zealand (Aotearoa).

The strategy in New Zealand (Aotearoa) to eliminate coronavirus disease requires that international arrivals undergo managed isolation and quarantine and mandatory testing for severe acute respiratory syndrome coronavirus 2. Combining genomic and epidemiologic data, we investigated the origin of an acute case of coronavirus disease identified in the community after the patient had spent 14 days in managed isolation and quarantine and had 2 negative test results. By combining genomic sequence analysis and epidemiologic investigations, we identified a multibranched chain of transmission of this virus, including on international and domestic flights, as well as a probable case of aerosol transmission without direct person-to-person contact. These findings show the power of integrating genomic and epidemiologic data to inform outbreak investigations.

The epidemiology of listeriosis in pregnant women and children in New Zealand from 1997 to 2016: an observational study.

BACKGROUND: Listeria monocytogenes causes the foodborne infection listeriosis. Pregnant women, infants and immunocompromised children are at increased risk for infection. The aim of this study was to describe the trends in the epidemiology of disease notifications and hospital admissions due to listeriosis in pregnant women aged 15 to 45 years and children aged less than 15 years in New Zealand (NZ) from 1997 to 2016. METHODS: In this population-based descriptive study, listeriosis notification and hospitalization rates from 1997 to 2016 were analyzed. Notification data were extracted from the Institute of Environmental Science and Research (ESR) Notifiable Diseases Database (EpiSurv) and hospitalization data were extracted from the National Minimum Dataset (NMDS). Pregnant women aged 15 to 45 years and children less than 15 years of age were included. Subgroup analysis was conducted for age and ethnicity. Outcomes of infection were described. RESULTS: In the 20-year period considered, there were 147 pregnancy-associated cases of listeriosis either notified to ESR (n = 106) and/or coded in the NMDS (n = 99), giving a crude incidence rate of 12.3 (95% CI 10.4, 14.4) per 100,000 births. In addition, there were 22 cases in children aged 28 days to < 15 years (incidence =0.12, 95% CI 0.08 to 0.19 per 100,000). There were no trends observed over time in the incidence of pregnancy-associated listeriosis. Incidence rates of pregnancy-associated and childhood listeriosis were highest in people of Pacific and Asian ethnicity. CONCLUSIONS: NZ has a low incidence of listeriosis in pregnant women and children, however, the consequences of infection are frequently severe. Those of Pacific and Asian ethnicity have the highest rates of disease and future messaging around food safety should target these groups. This study provides important insights into the epidemiology of listeriosis in pregnant women and children in NZ.

The epidemiology of non-viral gastroenteritis in New Zealand children from 1997 to 2015: an observational study.

BACKGROUND: Acute gastroenteritis is a substantial cause of hospitalization in children. Shigella, Salmonella, Campylobacter, Yersinia, enterotoxigenic Escherichia coli (ETEC), Giardia and Cryptosporidium are gastrointestinal pathogens that are notifiable in New Zealand (NZ). The impact of these infections in the pediatric population has not yet been analyzed. The aim of this study was to describe the epidemiological trends in disease notifications and hospital admissions due to non-viral gastroenteritis in NZ children. METHODS: In this population-based descriptive study, age-specific and age-standardized notification and hospital admission rates were analyzed from 1997-to-2015 for Shigella, Salmonella, Campylobacter, Yersinia, ETEC, Giardia and Cryptosporidium infections in children < 15 years of age. Variations in disease by gender, age, ethnicity and geography were described. RESULTS: From 1997-to-2015 there were 74,454 notifications (57.6% male) and 3192 hospitalizations (56.4% male) due to non-viral gastroenteritis in NZ children aged < 15 years. There was an overall trend towards a reduction in disease notifications and hospitalizations, however each disease showed a unique pattern of change over time. Campylobacter was the pathogen most frequently notified, accounting for 51.7% of notifications and 43.4% of hospitalizations. The hospitalization-to-notification ratios were, from highest to lowest, Salmonella typhi (1:1.09), Shigella (1:4.0), ETEC (1:7.81), nontyphoidal Salmonella (1:13.1), Campylobacter (1:27.8), Yersinia (1:29.2), Cryptosporidium (1,33.4), and Giardia (1,72.5). Compared to females, male notification rates were approximately 40% higher for Campylobacter, 25% higher for Giardia and Yersinia, and 15% higher for Cryptosporidium and nontyphoidal Salmonella (p < 0.001). Notification rates were highest in children 1-4 years, with the exceptions of nontyphoidal Salmonella, Salmonella typhi and Yersinia. Notification rates for nontyphoidal Salmonella and Yersinia were highest in children < 1 year, and for Salmonella typhi those aged 5-9 years. Children < 1 year were most likely to be hospitalized. CONCLUSIONS: The incidence of non-viral gastroenteritis in NZ children reduced during the 19-year period considered. The burden of disease was highest in the community, with only a small percentage of cases requiring hospitalization. This study provides important insight into the non-viral causes of gastroenteritis in NZ children and how environmental influences and changes in food safety practices may have helped to reduce the burden of these diseases in children.

Effectiveness of border screening for detecting influenza in arriving airline travelers.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 °C or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

Hand sanitiser provision for reducing illness absences in primary school children: a cluster randomised trial.

BACKGROUND: The potential for transmission of infectious diseases offered by the school environment are likely to be an important contributor to the rates of infectious disease experienced by children. This study aimed to test whether the addition of hand sanitiser in primary school classrooms compared with usual hand hygiene would reduce illness absences in primary school children in New Zealand. METHODS AND FINDINGS: This parallel-group cluster randomised trial took place in 68 primary schools, where schools were allocated using restricted randomisation (1:1 ratio) to the intervention or control group. All children (aged 5 to 11 y) in attendance at participating schools received an in-class hand hygiene education session. Schools in the intervention group were provided with alcohol-based hand sanitiser dispensers in classrooms for the winter school terms (27 April to 25 September 2009). Control schools received only the hand hygiene education session. The primary outcome was the number of absence episodes due to any illness among 2,443 follow-up children whose caregivers were telephoned after each absence from school. Secondary outcomes measured among follow-up children were the number of absence episodes due to specific illness (respiratory or gastrointestinal), length of illness and illness absence episodes, and number of episodes where at least one other member of the household became ill subsequently (child or adult). We also examined whether provision of sanitiser was associated with experience of a skin reaction. The number of absences for any reason and the length of the absence episode were measured in all primary school children enrolled at the schools. Children, school administrative staff, and the school liaison research assistants were not blind to group allocation. Outcome assessors of follow-up children were blind to group allocation. Of the 1,301 and 1,142 follow-up children in the hand sanitiser and control groups, respectively, the rate of absence episodes due to illness per 100 child-days was similar (1.21 and 1.16, respectively, incidence rate ratio 1.06, 95% CI 0.94 to 1.18). The provision of an alcohol-based hand sanitiser dispenser in classrooms was not effective in reducing rates of absence episodes due to respiratory or gastrointestinal illness, the length of illness or illness absence episodes, or the rate of subsequent infection for other members of the household in these children. The percentage of children experiencing a skin reaction was similar (10.4% hand sanitiser versus 10.3% control, risk ratio 1.01, 95% CI 0.78 to 1.30). The rate or length of absence episodes for any reason measured for all children also did not differ between groups. Limitations of the study include that the study was conducted during an influenza pandemic, with associated public health messaging about hand hygiene, which may have increased hand hygiene among all children and thereby reduced any additional effectiveness of sanitiser provision. We did not quite achieve the planned sample size of 1,350 follow-up children per group, although we still obtained precise estimates of the intervention effects. Also, it is possible that follow-up children were healthier than non-participating eligible children, with therefore less to gain from improved hand hygiene. However, lack of effectiveness of hand sanitiser provision on the rate of absences among all children suggests that this may not be the explanation. CONCLUSIONS: The provision of hand sanitiser in addition to usual hand hygiene in primary schools in New Zealand did not prevent disease of severity sufficient to cause school absence. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12609000478213. Please see later in the article for the Editors' Summary.

A waterborne outbreak of campylobacteriosis in the South Island of New Zealand due to a failure to implement a multi-barrier approach.

Outbreaks of waterborne gastroenteritis continue to occur in developed countries. Darfield, a rural town in the South Island of New Zealand experienced an outbreak of campylobacteriosis following a transgression of Escherichia coli on 16 August 2012. A descriptive outbreak investigation was performed. As a result, 29 cases had a laboratory-confirmed diagnosis of campylobacteriosis and 138 were identified as probable cases. Heavy rains, contamination of water with animal effluent from nearby paddocks and failures in the treatment of drinking water led to pathogens being distributed through the town's water supply. A multi-barrier approach is advocated to ensure the quality of water and many countries have legislation or programmes to address this. Although legislation for water safety plans based on a multi-barrier approach is in place in New Zealand, at the time of the outbreak it was not a requirement for the Darfield water supply. In addition, despite the awareness of the importance of a multi-barrier approach, competing interests, including those from the agricultural industry and financial restraints on water suppliers, can prevent it from being implemented. Governments need to be more willing to enforce legislation and standards to protect the public from waterborne disease.

[Effectiveness of border screening for detecting Influenza in arriving airline travelers]. / Eficacia de la detección sistemática de la gripe en las fronteras en los viajeros que llegan por vía aérea.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 ºC or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

Effectiveness of border screening for detecting influenza in arriving airline travelers.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 °C or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

Pregnant women's knowledge of, and adherence to, New Zealand Food Safety in Pregnancy guidelines.

AIM: Pregnant women are at increased risk for contracting foodborne illness. Simple food safety precautions can prevent illness. The aim of this study was to examine pregnant women's knowledge of, and adherence to, the New Zealand Food Safety in Pregnancy guidelines. METHOD: Participants were recruited when attending antenatal clinics, and via online pregnancy support groups. Knowledge and behaviours were assessed by way of a self-administered questionnaire. RESULTS: In total, 205 women participated in this study; 100 from antenatal clinics, 105 via Facebook. The median knowledge score was 95% (interquartile range (IQR) 83-100%, minimum = 17.4%). Only 25% of participants answered all questions correctly. The median adherence score was 77% (IQR = 62-92%, minimum = 8%); 13% of participants reported complete adherence to the food safety guidelines. Mean knowledge scores in participants of Maori ethnicity (76.6%) were lower than in participants of European/other ethnicity (91.7%, p=0.004). Maori participants had the lowest mean adherence scores (63.2%) and this requires further investigation. CONCLUSIONS: The majority of participants reported continuing to consume foods considered unsafe in pregnancy. This study highlights the need for improved food safety education during pregnancy. The results also suggest a need for food safety guidance to be made more accessible and relevant to the needs of Maori women.

Screening for influenza infection in international airline travelers.

We sought the collaboration of an international airline and border control agencies to study the feasibility of entry screening to identify airline travelers at increased risk of influenza infection. Although extensive and lengthy negotiations were required, we successfully developed a multisector collaboration and demonstrated the logistical feasibility of our screening protocol. We also determined the staffing levels required for a larger study to estimate the prevalence of influenza in international airline travelers.

Epidemiology of Campylobacter Gastroenteritis in New Zealand Children and the Effect of The Campylobacter Strategy: A 20-year Observational Study.

BACKGROUND: Campylobacter species are a common cause of gastroenteritis in New Zealand (NZ) as well as worldwide. This study aimed to describe epidemiologic trends in disease notifications and hospital admissions because of Campylobacter gastroenteritis in NZ children from 1997 to 2016. METHODS: In this population-based descriptive study, age-specific and age-standardized notification and hospitalization rates were analyzed for Campylobacter infections in children <15 years of age. Variations in disease by time, sex, age, ethnicity and geography were described. RESULTS: During the 20-year period considered, there were 39,970 notifications (59.1% male) and 1458 hospitalizations (61.8% male) because of Campylobacter gastroenteritis in NZ children. Before 2006, notification rates increased by 3.4% annually [95% confidence interval (CI): 0.7%-6.2%], with a peak of 340 notifications per 100,000 children in 2003. The average percentage change (APC) in hospitalizations was 7.4% (95% CI: 4.0%-10.9%) in the same period. From 2006 to 2008, notification and hospitalization rates fell by 25% and 30%, respectively. Since 2008, age-standardized incidence rates have been stable at 161 notifications (APC: -3.1; 95% CI: 0.82 to -6.9) and 6.73 hospitalizations (APC: 2.2; 95% CI: -2.0 to 6.5) per 100,000 children per year. Notification rates were highest in children 1-4 years of age. Hospitalizations rates were highest in children <1 year of age. CONCLUSIONS: NZ has previously had high rates of Campylobacter gastroenteritis in children. Implementation of a national strategy to reduce foodborne Campylobacter infection appears to have contributed to an observed reduction in rates between 2006 and 2008. The burden of Campylobacter disease is highest in the community health setting, with only a small proportion of cases needing hospitalization.

Dispatches from the front-line: an analysis of fluoridation campaigns in southern New Zealand, 2002-2006.

OBJECTIVES: The paper aims to analyse recent campaigns for water fluoridation in the South Island and to identify lessons to be learned from the outcomes. DESIGN: The research uses a systematic case study analysis based on a public policy framework, drawing on key informants, public documents and participant observation of campaigns in five separate communities. RESULTS: Over a four-year period in five specific communities (Gore and Southland in 2004; Ashburton in 2002 and 2006; and Grey and Westland in 2005), the opportunity to introduce or retain fluoridation was rejected by local Councils. The extent of community understanding of the issues, the processes of engagement on the part of the health systems and the approaches to decision-making by Councils varied widely, but the main inputs to decisions were the rejection of expert health advice and a reliance on binding referenda or other assessments of the strength of community feeling. CONCLUSION: More evidence-based decision-making on fluoridation is required. Options at local level include tribunals and other mechanisms to support Councils, but it is likely that stronger national policy leadership and the application of robust health impact assessment may be necessary to ensure improved oral health and the reduction of inequalities.

Vaccine Impact on Long-term Trends in Invasive Bacterial Disease in New Zealand Children.

BACKGROUND: Vaccines against Haemophilus influenzae type B (Hib), Neisseria meningitidis and Streptococcus pneumoniae have been serially introduced into the New Zealand national immunization schedule since the 1990s. This study aimed to describe long-term trends in the rates of these invasive bacterial infections in children from New Zealand and compare these to recent UK data. METHODS: This population-based observational study used 2 national datasets that collect data about hospital discharges (National Minimum Dataset) and notifiable diseases (Epurv). Annual age-specific and age-standardized hospital admission rates and notification rates were analyzed for all children <15 years of age. RESULTS: Hospital admissions for Hib reduced by 79% during the 2 years after the introduction of the Hib vaccine (5.94-1.24/100,000). Meningococcal disease notifications fell by 75% over 8 years after the introduction of MeNZB vaccine (26.15-2.48/100,000) and have continued to decline. Meningococcal disease rates were lower than in the United Kingdom despite the absence of an ongoing meningococcal vaccination program in New Zealand (8.16 compared with 10.37/100,000 for 2007-2011). There rates of notifications and hospital admissions for pneumococcal disease were discordant, but both reduced substantially after the introduction of pneumococcal conjugate vaccines. Maori children had the highest rates of disease and the greatest reduction in rates after the introduction of both meningococcal and pneumococcal vaccines. CONCLUSIONS: Vaccines have had a substantial impact on the rates of invasive bacterial disease in children from New Zealand because of Hib, pneumococcus and meningococcus. Reductions in rates of disease have been greatest in Maori children, improving longstanding disparities in disease burden.

Young people's use of condoms and their perceived vulnerability to sexually transmitted infections.

OBJECTIVE: Although sexually transmitted infections (STIs) are most prevalent among young people, they do not use condoms consistently to prevent infection. This study examined young people's perceptions of vulnerability to STIs and pregnancy. METHOD: A cross-sectional survey on sexual behaviour was carried out on a stratified random sample of school-going Year 12 and Year 13 young people aged 16-18 years in Christchurch, New Zealand. RESULTS: 1,136 students participated in the study, half of whom were sexually active. Fewer than half of the sexually active participants (44.6%) used condoms on every occasion of sexual intercourse. Only 23% of participants reported that they felt vulnerable to acquiring an STI, with a quarter of respondents reporting not using condoms because they did not think that either they or their partner had an infection, and a quarter reported not using condoms because they used other contraceptive measures. CONCLUSIONS: The results of this study support the premise that young people are more concerned about preventing unwanted pregnancy than STIs. Their perception of low risk of acquiring STIs is not without substance, however, as it was established that there was a low prevalence of Chlamydia trachomatis among this school-going population. The key to achieving more consistent condom use for STI prevention for young people may be through finding ways to get them to accept that they are vulnerable to STIs, despite the low prevalence among their peers, because the consequences of infection are far-reaching.

Estimated community costs of an outbreak of campylobacteriosis resulting from contamination of a public water supply in Darfield, New Zealand.

AIM: To estimate the economic costs to the community of an outbreak of campylobacteriosis in August 2012 resulting from contamination of a public water supply in Darfield, New Zealand. METHOD: Probable incidence of waterborne disease was estimated. Reported cases were scrutinised to identify symptoms, duration, hospital admissions and those in the paid workforce. Extra public health and local authority costs were calculated. Estimated time off work was multiplied by the average wage to obtain a conservative estimate of lost production. Sensitivity analysis was used to estimate unreported cases and their associated costs. RESULTS: There were 138 cases of confirmed or probable campylobacter, of whom 46 sought a medical consultation. Taking into account the usual pyramid of non-notified cases, estimates of the population infected range between approximately 828 and 1987. The dominant societal cost is lost production from time off paid work. Forty-six per cent were in the paid workforce, indicating a total estimated economic cost of at least $714,527 but it could have been as high as $1.26 million, depending on estimates of unreported cases. CONCLUSION: The likely cause of the Darfield outbreak was faecal contamination of the water supply, which with a multi-barrier approach would have been entirely preventable. The results provide economic evidence to support upgrading of water supplies to provide safe water and prevent waterborne disease.

Evaluation of the Canterbury under-18 seasonal influenza vaccination programme.

AIM: To evaluate the performance of the 2013 Canterbury under-18 seasonal influenza vaccination programme (Christchurch, New Zealand). METHODS: Routinely collected under 18 influenza vaccination uptake data were analysed to determine levels of vaccination uptake and equity of uptake across ethnic groups (NZ European, Maori and Pacific) and by level of deprivation. Qualitative data were collected to identify strategies that helped to achieve high uptake in primary care practices and schools. RESULTS: Overall uptake of influenza vaccination in 2013 was 32.9%, (compared to 18.5% in 2012), close to the target of 40%. Overall uptake in primary care was higher than in the school-based programme (29.2% versus 19.7%). Maori students had higher uptake than NZ European students in the school-based programme. In primary care, uptake for both Maori and Pacific children was lower than overall uptake and there was a marked gradient in uptake by socioeconomic quintile, with 30.2% uptake in the least deprived quintile compared to 21.9% uptake in the most deprived quintile. CONCLUSIONS: The cumulative effect of 3 years' consistency in offering the under-18 influenza vaccination in primary care practices, assisted by a timely media campaign and additional awareness generated by the school-based programme, has resulted in a marked increase in uptake of the vaccine in primary care in 2013. However, this was not equitably distributed. The school-based programme achieved better equity of uptake by deprivation and ethnicity. The challenge is to achieve both high and equitable uptake.

Impact of improved treatment on disease burden of chronic hepatitis C in New Zealand.

BACKGROUND: We describe the burden of HCV infection and estimate the effect of four different treatment strategies to reduce HCV-related morbidity and mortality. METHODS: Baseline model parameters were based upon literature review and expert consensus, focusing on New Zealand data. Four scenarios were modelled: Scenario 1 estimated the impact of increased treatment efficacy, while Scenario 2 estimated the effect of increased treatment efficacy and gradual increases in numbers treated. Scenarios 3 and 4 estimated the impact of deferred introduction of new DAAs for either 1 or 2 years. RESULTS: Prevalence of HCV infection peaked in 2010 (50,480 cases). Peak prevalence of cirrhosis and HCC will occur after 2030. Scenario 2 resulted in sizeable decreases in HCV-related morbidity and mortality. The impact of Scenario 1 was smaller. Deferring funding for new DAA treatments for a further 1 or 2 years resulted in an 18-36% increase in liver-related deaths in 2030. CONCLUSIONS: While prevalence of chronic HCV infection may have peaked, disease burden continues to grow. Increased treatment uptake and efficacy combined with efforts to reduce disease transmission, will help prevent advanced liver disease and deaths.

HIV-related risk factors among black African migrants and refugees in Christchurch, New Zealand: results from the Mayisha-NZ survey.

AIM: To describe the demographic characteristics of, and HIV-related risk behaviours among, black African migrants and refugees in Christchurch. METHODS: A cross-sectional survey of black African migrants and refugees in Christchurch was carried out. Ten trained African community researchers recruited study participants in social venues and events frequented by Africans. A short self-completed questionnaire collected data on demographic characteristics, previous HIV testing, HIV risk perception, previous STI diagnosis, utilization of health services and sexual behaviours. RESULTS: Valid questionnaires were obtained from 245 respondents (150 men and 95 women) with a mean age of 28 years (range 16 to 58). Participants came from 13 different African countries. Risk factors for HIV identified in this study included: low condom use, low HIV risk perception, having more than one sexual partner, previous STI diagnosis and lack of voluntary testing for HIV. CONCLUSIONS: Our findings justify the need for developing an HIV prevention strategy for black Africans in New Zealand that is informed by local evidence. This strategy should also address sexual health needs of Africans including barriers to condom use, the availability of HIV/STI screening services and targeting sexual behaviours that increase vulnerability to HIV infection.

Pandemic influenza A(H1N1)pdm09: risk of infection in primary healthcare workers.

BACKGROUND: Healthcare workers in primary care are at risk of infection during an influenza pandemic. The 2009 influenza pandemic provided an opportunity to assess this risk. AIM: To measure the prevalence of seropositivity to influenza A(H1N1)pdm09 among primary healthcare workers in Canterbury, New Zealand, following the 2009 influenza pandemic, and to examine associations between seropositivity and participants' sociodemographic characteristics, professional roles, work patterns, and seasonal influenza vaccination status. DESIGN AND SETTING: An observational study involving a questionnaire and testing for influenza A(H1N1)pdm09 seropositivity in all primary healthcare workers in Canterbury, New Zealand between December 2009 and February 2010. Method Participants completed a questionnaire that recorded sociodemographic and professional data, symptoms of influenza-like illness, history of seasonal influenza vaccination, and work patterns. Serum samples were collected and haemagglutination inhibition antibody titres to influenza A(H1N1)pdm09 measured. RESULTS: Questionnaires and serum samples were received from 1027 participants, from a workforce of 1476 (response rate 70%). Seropositivity was detected in 224 participants (22%). Receipt of seasonal influenza vaccine (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.2 to 3.3), recall of influenza (OR = 1.9, 95% CI = 1.3 to 2.8), and age ≤45 years (OR = 1.4, 95% CI = 1.0 to 1.9) were associated with seropositivity. CONCLUSION: A total of 22% of primary care healthcare workers were seropositive. Younger participants, those who recalled having influenza, and those who had been vaccinated against seasonal influenza were more likely to be seropositive. Working in a dedicated influenza centre was not associated with an increased risk of seropositivity.