Virus shedding and environmental deposition of novel A (H1N1) pandemic influenza virus: interim findings

Killingley, Ben; Greatorex, Jane; Cauchemez, Simon; Enstone, Je E.; Curran, Martin D.; Read, R.C.; Lim, Wee Shiong; Hayward, Andrew; Nicholson, K.G.; Nguyen-Van-Tam, Jonathan S.

doi:10.3310/hta14460-04

Cited by 31 publications

(35 citation statements)

References 27 publications

(36 reference statements)

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“…Two randomized trials where influenza patients with naturally acquired infection were treated with oseltamivir no later than 36 hours after symptom onset also showed a significant reduction of severity, but differed in their assessment of the effect on viral shedding [33], [34]. Observational studies where requirements for oseltamivir treatment permitted treatment inception up to 48 hours after symptom onset often failed to demonstrate significant effects in viral shedding parameters [6], [28], [29] and our study is no exception in this regard.…”

Section: Discussionmentioning

confidence: 48%

“…A few smaller studies on influenza (H1N1)pdm09 have also not been able to show significant age-dependent differences in the duration of viral shedding [28], [29], although others, both in seasonal [30] and pandemic influenza A(H1N1)pdm09 [31], have. The latter study was conducted among patients hospitalised with A(H1N1)pdm09 and demonstrated very clearly that duration of shedding is prolonged in hospitalised children <13 years [31].…”

Section: Discussionmentioning

confidence: 94%

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Comparison of Shedding Characteristics of Seasonal Influenza Virus (Sub)Types and Influenza A(H1N1)pdm09; Germany, 2007–2011

et al. 2012

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BackgroundInfluenza viral shedding studies provide fundamental information for preventive strategies and modelling exercises. We conducted a prospective household study to investigate viral shedding in seasonal and pandemic influenza between 2007 and 2011 in Berlin and Munich, Germany.MethodsStudy physicians recruited index patients and their household members. Serial nasal specimens were obtained from all household members over at least eight days and tested quantitatively by qRT-PCR for the influenza virus (sub)type of the index patient. A subset of samples was also tested by viral culture. Symptoms were recorded daily.ResultsWe recruited 122 index patients and 320 household contacts, of which 67 became secondary household cases. Among all 189 influenza cases, 12 were infected with seasonal/prepandemic influenza A(H1N1), 19 with A(H3N2), 60 with influenza B, and 98 with A(H1N1)pdm09. Nine (14%) of 65 non-vaccinated secondary cases were asymptomatic/subclinical (0 (0%) of 21 children, 9 (21%) of 44 adults; p = 0.03). Viral load among patients with influenza-like illness (ILI) peaked on illness days 1, 2 or 3 for all (sub)types and declined steadily until days 7–9. Clinical symptom scores roughly paralleled viral shedding dynamics. On the first day prior to symptom onset 30% (12/40) of specimens were positive. Viral load in 6 asymptomatic/subclinical patients was similar to that in ILI-patients. Duration of infectiousness as measured by viral culture lasted approximately until illness days 4–6. Viral load did not seem to be influenced by antiviral therapy, age or vaccination status.ConclusionAsymptomatic/subclinical infections occur infrequently, but may be associated with substantial amounts of viral shedding. Presymptomatic shedding may arise in one third of cases, and shedding characteristics appear to be independent of (seasonal or pandemic) (sub)type, age, antiviral therapy or vaccination; however the power to find moderate differences was limited.

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Section: Discussionmentioning

confidence: 48%

Section: Discussionmentioning

confidence: 94%

Comparison of Shedding Characteristics of Seasonal Influenza Virus (Sub)Types and Influenza A(H1N1)pdm09; Germany, 2007–2011

et al. 2012

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“…In addition to RT‐PCR, five studies measured viral shedding by culture. Two studies measured viral shedding by culture for all study participants, and for 63% and 73% of patients in the other three studies. With the exception of one study in which median values were the same and the means differed by 0·3 day, the mean and median durations of viral shedding were 1·5–2 days shorter when measured by culture.…”

Section: Resultsmentioning

confidence: 99%

Systematic review of influenza A(H1N1)pdm09 virus shedding: duration is affected by severity, but not age

Fielding

Kelly

Mercer

et al. 2013

Influenza Resp Viruses

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Duration of viral shedding following infection is an important determinant of disease transmission, informing both control policies and disease modelling. We undertook a systematic literature review of the duration of influenza A(H1N1)pdm09 virus shedding to examine the effects of age, severity of illness and receipt of antiviral treatment. Studies were identified by searching the PubMed database using the keywords ‘H1N1’, ‘pandemic’, ‘pandemics’, ‘shed’ and ‘shedding’. Any study of humans with an outcome measure of viral shedding was eligible for inclusion in the review. Comparisons by age, degree of severity and antiviral treatment were made with forest plots. The search returned 214 articles of which 22 were eligible for the review. Significant statistical heterogeneity between studies precluded meta-analysis. The mean duration of viral shedding generally increased with severity of clinical presentation, but we found no evidence of longer shedding duration of influenza A(H1N1)pdm09 among children compared with adults. Shorter viral shedding duration was observed when oseltamivir treatment was administered within 48 hours of illness onset. Considerable differences in the design and analysis of viral shedding studies limit their comparison and highlight the need for a standardised approach. These insights have implications not only for pandemic planning, but also for informing responses and study of seasonal influenza now that the A(H1N1)pdm09 virus has become established as the seasonal H1N1 influenza virus.

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“…Influenza virus RNA has been detected in respirable airborne particles collected in healthcare facilities and other locations 9, 10, 11, 12, 13, 14, 15, 16. Influenza virus RNA also has been found in aerosol particles collected directly from infected patients while they were coughing and breathing 17, 18, 19, 20, 21, 22, 23. Six studies have demonstrated that influenza patients expel airborne particles containing viable virus 13, 18, 19, 21, 24, 25.…”

Section: Introductionmentioning

confidence: 99%

Viable influenza A virus in airborne particles expelled during coughs versus exhalations

Lindsley

Blachère

Beezhold

et al. 2016

Influenza Resp Viruses

139

117

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BackgroundTo prepare for a possible influenza pandemic, a better understanding of the potential for the airborne transmission of influenza from person to person is needed.ObjectivesThe objective of this study was to directly compare the generation of aerosol particles containing viable influenza virus during coughs and exhalations.MethodsSixty‐one adult volunteer outpatients with influenza‐like symptoms were asked to cough and exhale three times into a spirometer. Aerosol particles produced during coughing and exhalation were collected into liquid media using aerosol samplers. The samples were tested for the presence of viable influenza virus using a viral replication assay (VRA).ResultsFifty‐three test subjects tested positive for influenza A virus. Of these, 28 (53%) produced aerosol particles containing viable influenza A virus during coughing, and 22 (42%) produced aerosols with viable virus during exhalation. Thirteen subjects had both cough aerosol and exhalation aerosol samples that contained viable virus, 15 had positive cough aerosol samples but negative exhalation samples, and 9 had positive exhalation samples but negative cough samples.ConclusionsViable influenza A virus was detected more often in cough aerosol particles than in exhalation aerosol particles, but the difference was not large. Because individuals breathe much more often than they cough, these results suggest that breathing may generate more airborne infectious material than coughing over time. However, both respiratory activities could be important in airborne influenza transmission. Our results are also consistent with the theory that much of the aerosol containing viable influenza originates deep in the lungs.

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Virus shedding and environmental deposition of novel A (H1N1) pandemic influenza virus: interim findings

Cited by 31 publications

References 27 publications

Comparison of Shedding Characteristics of Seasonal Influenza Virus (Sub)Types and Influenza A(H1N1)pdm09; Germany, 2007–2011

Comparison of Shedding Characteristics of Seasonal Influenza Virus (Sub)Types and Influenza A(H1N1)pdm09; Germany, 2007–2011

Systematic review of influenza A(H1N1)pdm09 virus shedding: duration is affected by severity, but not age

Viable influenza A virus in airborne particles expelled during coughs versus exhalations

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