Comparison of Pandemic (H1N1) 2009 and Seasonal Influenza Viral Loads, Singapore

Lee, Chun K.; Lee, Hong K.; Loh, Tze Ping; Lai, Florence Yuk Lin; Tambyah, Paul A.; Chiu, Lily; Koay, Evelyn Siew-Chuan; Tang, Julian W.

doi:10.3201/eid1702.100282

Cited by 34 publications

(34 citation statements)

References 14 publications

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“…RIDT sensitivities were similar within age groups for the three RIDT kits; although sensitivity of the Xpect for younger than two age group appeared to be slightly higher, it was likely due to the small sample size ( n = 1) included in this group. However, decreased RIDT sensitivity with increasing age was observed in all the three RIDT kits and is thought to be due to decreased levels of viral shedding in older patients 12 , 13 . These data indicate that our finding that RIDT sensitivity decreased with increasing age is independent of RIDT kit.…”

Section: Discussionsupporting

confidence: 56%

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Detection of 2009 pandemic influenza A(H1N1) virus Infection in different age groups by using rapid influenza diagnostic tests

Gao¹,

Loring²,

Laviolette³

et al. 2011

Influenza Resp Viruses

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Please cite this paper as: Gao et al. (2011) Detection of 2009 pandemic influenza A(H1N1) virus Infection in different age groups by using rapid influenza diagnostic tests. Influenza and Other Respiratory Viruses 6(3), e30–e34. Background The performance of rapid influenza diagnostic tests (RIDTs) in detecting influenza A(H1N1) 2009 has varied widely. Evaluations of RIDTs among infected individuals across all age groups have not been described in depth. Objectives Determine RIDT clinical sensitivity in comparison with influenza detection using real‐time RT‐PCR among patients infected with influenza A(H1N1) 2009 across all age groups. Study design This study analyzed respiratory specimens received by the New Hampshire Public Health Laboratories (NHPHL) from September 1, 2009, through December 31, 2009. RIDT performance was evaluated among different age groups of patients determined to be infected with influenza A (H1N1) 2009, and the association between age and RIDT sensitivity was determined. Results Of 1373 specimens examined, 269 tested positive for influenza A(H1N1) 2009 by real‐time RT‐PCR (rRT‐PCR) and had RIDT results available. Overall clinical sensitivity and specificity of RIDTs were 53·9 and 98·5%, respectively. By age group, clinical sensitivity was 85·7% in patients <2 years old, 60·3% in patients between 2‐ and 39 years old, and 33·3% in patients aged 40 and older. Logistic regression analysis indicated that increasing age was negatively associated with RIDT performance. Conclusion Rapid influenza diagnostic test sensitivity decreased significantly with increasing age. Findings from this study may impact a clinician’s interpretation of RIDT test results and ultimately have implications in clinical decision‐making.

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Section: Discussionsupporting

confidence: 56%

“…These data demonstrate that RIDT sensitivity is significantly impacted by age of patients. Thus, clinicians should understand the limitation of RIDT 12 and carefully evaluate negative RIDT results, especially for tests performed on older patients.…”

Section: Discussionmentioning

confidence: 99%

Detection of 2009 pandemic influenza A(H1N1) virus Infection in different age groups by using rapid influenza diagnostic tests

Gao¹,

Loring²,

Laviolette³

et al. 2011

Influenza Resp Viruses

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“…Primary clinical specimens collected directly from patients vary in amount of viruses, depending on when the samples were taken post-symptom onset [41]. Even so, our study showed that the rate of MDCK-induced mutation did not correlate with the viral titers (Ct values) of the clinical samples, suggesting that this was more of a sporadic event, rather than one that was necessarily viral load dependent.…”

Section: Discussionmentioning

confidence: 71%

Comparison of Mutation Patterns in Full-Genome A/H3N2 Influenza Sequences Obtained Directly from Clinical Samples and the Same Samples after a Single MDCK Passage

et al. 2013

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Human influenza viruses can be isolated efficiently from clinical samples using Madin-Darby canine kidney (MDCK) cells. However, this process is known to induce mutations in the virus as it adapts to this non-human cell-line. We performed a systematic study to record the pattern of MDCK-induced mutations observed across the whole influenza A/H3N2 genome. Seventy-seven clinical samples collected from 2009-2011 were included in the study. Two full influenza genomes were obtained for each sample: one from virus obtained directly from the clinical sample and one from the matching isolate cultured in MDCK cells. Comparison of the full-genome sequences obtained from each of these sources showed that 42% of the 77 isolates had acquired at least one MDCK-induced mutation. The presence or absence of these mutations was independent of viral load or sample origin (in-patients versus out-patients). Notably, all the five hemagglutinin missense mutations were observed at the hemaggutinin 1 domain only, particularly within or proximal to the receptor binding sites and antigenic site of the virus. Furthermore, 23% of the 77 isolates had undergone a MDCK-induced missense mutation, D151G/N, in the neuraminidase segment. This mutation has been found to be associated with reduced drug sensitivity towards the neuraminidase inhibitors and increased viral receptor binding efficiency to host cells. In contrast, none of the neuraminidase sequences obtained directly from the clinical samples contained the D151G/N mutation, suggesting that this mutation may be an indicator of MDCK culture-induced changes. These D151 mutations can confound the interpretation of the hemagglutination inhibition assay and neuraminidase inhibitor resistance results when these are based on MDCK isolates. Such isolates are currently in routine use in the WHO influenza vaccine and drug-resistance surveillance programs. Potential data interpretation miscalls can therefore be avoided by careful exclusion of such D151 mutants after further sequence analysis.

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“…Comorbidity significantly increased peak viral load for H1N1, but not for pH1N1. For pH1N1, Lee et al …”

Section: Discussionmentioning

confidence: 99%

“…We were unable to assess comorbidity associations for H3N2 from our data set, as the sample size was too small. However, Lee et al . suggested that comorbidity was significantly associated with viral loads for hospitalized H3N2 cases.…”

Section: Discussionmentioning

confidence: 99%

Predictors of influenza a molecular viral shedding in Hutterite communities

Wang

Russell

Fonseca

et al. 2017

Influenza Resp Viruses

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BackgroundPatterns of influenza molecular viral shedding following influenza infection have been well established; predictors of viral shedding however remain uncertain.ObjectivesWe sought to determine factors associated with peak molecular viral load, duration of shedding, and viral area under the curve (AUC) in children and adult Hutterite colony members with laboratory‐confirmed influenza.MethodsA cohort study was conducted in Hutterite colonies in Alberta, Canada. Flocked nasal swabs were collected during three influenza seasons (2007‐2008 to 2009‐2010) from both symptomatic and asymptomatic individuals infected with influenza. Samples were tested by real‐time reverse‐transcription polymerase chain reaction for influenza A and influenza B, and the viral load was determined for influenza A‐positive samples.ResultsFor seasonal H1N1, younger age was associated with a larger AUC, female sex was associated with decreased peak viral load and reduced viral shedding duration, while the presence of comorbidity was associated with increased peak viral load. For H3N2, younger age was associated with increased peak viral load and increased AUC. For pandemic H1N1, younger age was associated with increased peak viral load and increased viral AUC, female sex was associated with reduced peak viral load, while inapparent infection was associated with reduced peak viral load, reduced viral shedding duration, and reduced viral AUC.ConclusionsPatterns of molecular viral shedding vary by age, sex, comorbidity, and the presence of symptoms. Predictor variables vary by influenza A subtype.

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Comparison of Pandemic (H1N1) 2009 and Seasonal Influenza Viral Loads, Singapore

Cited by 34 publications

References 14 publications

Detection of 2009 pandemic influenza A(H1N1) virus Infection in different age groups by using rapid influenza diagnostic tests

Detection of 2009 pandemic influenza A(H1N1) virus Infection in different age groups by using rapid influenza diagnostic tests

Comparison of Mutation Patterns in Full-Genome A/H3N2 Influenza Sequences Obtained Directly from Clinical Samples and the Same Samples after a Single MDCK Passage

Predictors of influenza a molecular viral shedding in Hutterite communities

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