Jan Gralton

Protecting healthcare workers from pandemic influenza: N95 or surgical masks?

Objective: The successful management of an influenza pandemic will be reliant on the expertise of healthcare workers at high risk for occupationally acquired influenza. Recommended infection control measures for healthcare workers include surgical masks to protect against droplet-spread respiratory transmissible infections and N95 masks to protect against aerosol-spread infections. A literature review was undertaken for evidence of superior protective value of N95 masks or surgical masks for healthcare workers against influenza and extraneous factors influencing conferred protection. Methods: Four scientific search engines using 12 search sequences identified 21 mask studies in healthcare settings for the prevention of transmission of respiratory syncytial virus, Bordetella pertussis, and severe acute respiratory syndrome. Each was critically assessed in accordance with Australian National Health Medical Research Council guidelines. An additional 25 laboratory-based publications were also reviewed. Results: All studies reviewed used medium or lower level evidence study design. In the majority of studies, important confounders included the unrecognized impact of concurrent bundling of other infection control measures, mask compliance, contamination from improper doffing of masks, and ocular inoculation. Only three studies directly compared the protective value of surgical masks with N95 masks. The majority of laboratory studies identified both mask types as having a range of filtration efficiency, yet N95 masks afford superior protection against particles of a similar size to influenza. Conclusions: World Health Organization guidelines recommend surgical masks for all patient care with the exception of N95 masks for aerosol generating procedures. Because of the paucity of high-quality studies in the healthcare setting, the advocacy of mask types is not entirely evidence-based. Evidence from laboratory studies of potential airborne spread of influenza from shedding patients indicate that guidelines related to the current 1-meter respiratory zone may need to be extended to a larger respiratory zone and include protection from ocular inoculation.

Respiratory virus RNA is detectable in airborne and droplet particles

Aerosol transmission routes of respiratory viruses have been classified by the WHO on the basis of equilibrium particle size. Droplet transmission is associated with particles sized >5 µm in diameter and airborne transmission is associated with particles sized ≤5 µm in diameter. Current infection control measures for respiratory viruses are directed at preventing droplet transmission, although epidemiological evidence suggests concurrent airborne transmission also occurs. Understanding the size of particles carrying viruses can be used to inform infection control procedures and therefore reduce virus transmission. This study determined the size of particles carrying respiratory viral RNA produced on coughing and breathing by 12 adults and 41 children with symptomatic respiratory infections. A modified six‐stage Andersen Sampler collected expelled particles. Each stage was washed to recover samples for viral RNA extraction. Influenza A and B, parainfluenza 1, 2 and 3, respiratory syncytial virus (RSV), human metapneumovirus and human rhinoviruses (hRV) were detected using RT‐PCR. On breathing, 58% of participants produced large particles (>5 µm) containing viral RNA and 80% produced small particles (≤5 µm) carrying viral RNA. On coughing, 57% of participants produced large particles containing viral RNA and 82% produced small particles containing viral RNA. Forty five percent of participants produced samples positive for hRV viral RNA and 26% of participants produced samples positive for viral RNA from parainfluenza viruses. This study demonstrates that individuals with symptomatic respiratory viral infections produce both large and small particles carrying viral RNA on coughing and breathing. J. Med. Virol. 85:2151–2159, 2013.

Sleep disturbance in persistent allergic rhinitis measured using actigraphy

BACKGROUND Tiredness, fatigue, and impaired quality of life are common in patients with persistent allergic rhinitis (PAR). These symptoms may also be associated with reduced sleep quality in individuals with rhinitis. OBJECTIVE To determine whether sleep disturbance can be detected using actigraphy in patients with PAR. METHODS Ten house dust mite-allergic rhinitic patients and 10 nonallergic nonrhinitic control subjects were studied for 5 consecutive days and night. Continuous activity monitoring during the study period using actigraphy was used to obtain markers of sleep quality, such as sleep onset, sleep duration, and sleep fragmentation. In addition, participants recorded in a sleep diary the time they went to bed, the time they went to sleep, the time they awoke, and the quality of their sleep. RESULTS Allergic rhinitic patients were found to have an increased fragmentation index value, indicative of reduced sleep quality and increased sleep disturbance, compared with the control group (P = .007). CONCLUSIONS Using actigraphy, we identified specific sleep disturbances in patients with PAR that may result in the increased tiredness, fatigue, and impaired quality of life typically experienced in such patients.

Personal clothing as a potential vector of respiratory virus transmission in childcare settings

Previous investigations of fomite transmission have focused on the presence of pathogens on inanimate objects in clinical settings. There has been limited investigation of fomite transmission in non‐clinical pediatric settings where there is a high prevalence of respiratory virus infections. Over a 5 week period, this study investigated whether the personal clothing of teachers working in childcare centers was contaminated with viral RNA, and potentially could mediate virus transmission. Matched morning and evening clothing and nasal samples were collected for 313 teacher work days (TWDs). Human rhinoviruses (hRV) RNA were detected from samples using real‐time PCR. Human rhinovirus RNA was detected in clothing samples on 16 TWDs and in nasal samples on 32 TWDs. There were no TWDs when teachers provided both positive nasal and clothing samples and only three TWDs when hRV persisted on clothing for the entire day. The detection of hRV RNA was significantly predicted by self‐recognition of symptomatic illness by the teacher 2 days prior to detection. These findings suggest that teachers’ personal clothing in childcare settings is unlikely to facilitate the transmission of hRV. J. Med. Virol. 87:925–930, 2015.

Using evidence-based medicine to protect healthcare workers from pandemic influenza: Is it possible?

Objective:To use evidence-based principles to develop infection control algorithms to ensure the protection of healthcare workers and the continuity of health service provision during a pandemic. Design:Evidence-based algorithms were developed from published research as well as “needs and values” assessments. Research evidence was obtained from 97 studies reporting the protectiveness of antiviral prophylaxis, seasonal vaccination, and mask use. Needs and values assessments were undertaken by international experts in pandemic infection control and local healthcare workers. Opportunity and resources costs were not determined. Setting:The Australian government commissioned the development of an evidence-based algorithm for inclusion in the 2008 revision of the Australian Health and Management Plan for Pandemic Influenza. Participants:Two international infection control teams responsible for healthcare worker safety during the Severe Acute Respiratory Syndrome outbreak reviewed the evidence-based algorithms. The algorithms were then reviewed for needs and values by eight local clinicians who were considered key frontline clinicians during the contain and sustain phases. The international teams reviewed for practicability of implementation, whereas local clinicians reviewed for clinician compliance. Results:Despite strong evidence for vaccination and antiviral prophylaxis providing significant protection, clinicians believed they required the additional combinations of both masks and face shields. Despite the equivocal evidence for the efficacy of surgical and N95 masks and the provision of algorithms appropriate for the level of risk according to clinical care during a pandemic, clinicians still demanded N95 masks plus face shields in combination with prophylaxis and novel vaccination. Conclusions:Conventional evidence-based principles could not be applied to formulate recommendations due to the lack of pandemic-specific efficacy data of protection tools and the inherent unpredictability of pandemics. As an alternative, evidence-based principles have been used to formulate recommendations while giving priority to the needs and values of healthcare workers over the research evidence.

Prevalence of cytomegalovirus carriage among childcare staff

Primary cytomegalovirus (CMV) infection during pregnancy carries a high risk (~30%) of transplacental transmission to the developing fetus, which may result in congenital CMV and consequent disease in the newborn. An estimated 2000 Australian children are born with congenital CMV each year, with 25% developing life-long sequelae, including hearing loss and mental disability. Higher rates of CMV infection occur with increasing age (seroprevalence: 34.9% for <20 years of age, 72.4% for >50 years of age), household crowding and attendance at childcare. Children shed high levels of CMV in saliva and urine and frequently acquire CMV from other children. Exposure of childcare staff through changing nappies (diapers), feeding and contact with contaminated environmental surfaces potentially increases their risk of acquiring CMV. Data from France and other developed countries show higher rates of paediatric shedding in childcare (50% in childcare vs. 20% in controls in emergency department at age of 3 months to 6 years), measured using sensitive and specific assays such as salivary real-time polymerase chain reaction. However, no published study has determined prevalence of CMV in childcare staff in Australia, and shedding of this virus from saliva or other sites has not been examined systematically. We examined CMV excretion among childcare staff from two childcare centres in Sydney using our published methods for viral sampling of nasal and clothing surfaces under South Eastern Sydney Local Health District ethics approval no. 10332. We tested 114 clothing samples and 125 nasal samples collected from 20 childcare staff from two university childcare centres in Sydney over 5 weeks in 2011. DNA was extracted and real-time polymerase chain reaction (assay limit of detection 10 copies) was performed using CMV major immediate early gene primers. Of 125 nasal swabs tested, 6 (5%) were positive for CMV DNA, giving rise to an overall CMV excretion rate of 30% (6/20) among childcare staff. However, of 114 clothing swabs tested, none were positive for CMV DNA, which suggests clothing was unlikely to be a vector of fomite transmission at these childcare centres, contrasting our previous findings for respiratory virus detection on clothes of childcare staff. The CMV detection rate among nasal secretions of childcare staff suggests there is a need for education regarding effective hygiene measures to prevent CMV transmission and acquisition, particularly for pregnant staff. Measures shown to reduce CMV infection include not sharing food, utensils, cups or washcloths with a child; regular handwashing; and not kissing a child on or near the mouth. Until an effective therapy is available, educating childcare staff regarding these hygiene measures remains the best preventive strategy for congenital CMV infection and subsequently congenital CMV disease. Dr Wendy J van Zuylen Mr Qing Y Zheng Dr Stuart T Hamilton Ms Ece E Egilmezer Professor Maria E Craig Dr Jan Gralton Professor William D Rawlinson Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Schools of Medical Sciences, Women’s and Children’s Health and Biotechnology and Biomolecular Sciences University of New South Wales Sydney, New South Wales Australia