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Cited by 323Influenza Virus Research StudiesPneumonia and Respiratory InfectionsRespiratory viral infections research

The role of pneumonia and secondary bacterial infection in fatal and serious outcomes of pandemic influenza a(H1N1)pdm09.

Open access
MacIntyre, Chandini Raina, Chughtai, Abrar Ahmad, Barnes, Michelle, Ridda, Iman, Seale, Holly, Toms, Renin, Heywood, Anita·2018·BMC Infectious Diseases
DOI 10.1186/s12879-018-3548-0PMC PMC6286525
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Abstract

BACKGROUND: The aim of this study was to estimate the prevalence of pneumonia and secondary bacterial infections during the pandemic of influenza A(H1N1)pdm09. METHODS: A systematic review was conducted to identify relevant literature in which clinical outcomes of pandemic influenza A(H1N1)pdm09 infection were described. Published studies (between 01/01/2009 and 05/07/2012) describing cases of fatal or hospitalised A(H1N1)pdm09 and including data on bacterial testing or co-infection. RESULTS: Seventy five studies met the inclusion criteria. Fatal cases with autopsy specimen testing were reported in 11 studies, in which any co-infection was identified in 23% of cases (Streptococcus pneumoniae 29%). Eleven studies reported bacterial co-infection among hospitalised cases of A(H1N1)2009pdm with confirmed pneumonia, with a mean of 19% positive for bacteria (Streptococcus pneumoniae 54%). Of 16 studies of intensive care unit (ICU) patients, bacterial co-infection identified in a mean of 19% of cases (Streptococcus pneumoniae 26%). The mean prevalence of bacterial co-infection was 12% in studies of hospitalised patients not requiring ICU (Streptococcus pneumoniae 33%) and 16% in studies of paediatric patients hospitalised in general or pediatric intensive care unit (PICU) wards (Streptococcus pneumoniae 16%). CONCLUSION: We found that few studies of the 2009 influenza pandemic reported on bacterial complications and testing. Of studies which did report on this, secondary bacterial infection was identified in almost one in four patients, with Streptococcus pneumoniae the most common bacteria identified. Bacterial complications were associated with serious outcomes such as death and admission to intensive care. Prevention and treatment of bacterial secondary infection should be an integral part of pandemic planning, and improved uptake of routine pneumococcal vaccination in adults with an indication may reduce the impact of a pandemic.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review of 75 studies found that secondary bacterial infection complicated a substantial minority of severe or fatal pandemic influenza A(H1N1)pdm09 cases, with Streptococcus pneumoniae the most commonly identified pathogen. The authors conclude that bacterial complications were associated with death and ICU admission, and that prevention and treatment of secondary bacterial infection should be part of pandemic planning.

Key findings

  • Among fatal cases with autopsy specimen testing, any co-infection was identified in 23% of cases, with Streptococcus pneumoniae in 29%.
  • Among hospitalised cases with confirmed pneumonia, a mean of 19% tested positive for bacteria, with Streptococcus pneumoniae in 54%; among ICU patients, bacterial co-infection was identified in a mean of 19%, with Streptococcus pneumoniae in 26%.
  • Mean bacterial co-infection prevalence was 12% in hospitalised patients not requiring ICU (Streptococcus pneumoniae 33%) and 16% in paediatric patients hospitalised in general or PICU wards (Streptococcus pneumoniae 16%).
  • The overall rate of bacterial infection was significantly higher in fatal versus nonfatal cases (OR 1.71, 95% CI 1.33–2.20), and S. pneumoniae co-infection was associated with higher mortality in one large Argentina ICU study (OR 2.72, 95% CI 1.05–7.06) despite concurrent antibiotics.

Methods

  • Systematic review conducted according to PRISMA, searching Medline, Pre-Medline, EmBASE and LILACS for English-language human studies published 01/01/2009–05/07/2012, plus hand-searching reference lists.
  • Included observational studies reporting ≥10 influenza A(H1N1)pdm09 patients with bacterial infections at any sterile site, restricted to fatal or hospitalised confirmed/probable cases; excluded specific at-risk populations, case reports/series <10, and ambulatory cases without hospital admission or death outcomes.
  • From 7845 identified studies, 75 met inclusion criteria; data were extracted independently by two reviewers, with discrepancies resolved by a senior reviewer. Variability precluded quantitative meta-analysis, so results were summarised separately for fatal cases, hospitalised pneumonia cases, ICU patients, general ward patients, and paediatric patients.

Limitations

  • The paper states that variability of available data precluded quantitative meta-analysis, that many studies did not clarify whether pneumonia was community- or hospital-acquired, and that samples and timing of sampling were not adequately described in most studies.
  • The paper states that bacterial co-infection may be underestimated because many cases were not tested, bacterial pneumonia cannot always be differentiated from viral pneumonia by clinical presentation, radiology, and routine blood tests, and no standardised testing protocol existed for fatal cases.
  • Evident from the text: included studies were heterogeneous observational designs with varying definitions and testing proportions, some included probable rather than PCR-confirmed cases, and the search was limited to English-language publications up to 2012.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1186/s12879-018-3548-0

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 59 cited sources checked · 0 supported · 0 flagged

  • Findingcitation

    Among fatal A(H1N1)pdm09 cases with autopsy specimen testing, any bacterial co-infection was identified in a mean of 23% of cases.

    “Fatal cases with autopsy specimen testing were reported in 11 studies, in which any co-infection was identified in 23% of cases”
    • Also stated in: § Bacterial co-infection among fatal cases of A(H1N1)2009pdm · plain
      “positive bacterial growth ranged from 2 to 38% (mean bacterial 23%) [9] of autopsied cases.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9] Madhi SA, Klugman KP. A role for Streptococcus pneumoniae in virus-associated pneumonia. Nat Med. 2004;10:811–3 Epub 2004/07/13. source

      Not checked in the free run.

  • Findingown data

    Among hospitalised A(H1N1)pdm09 patients not requiring ICU, the mean prevalence of bacterial co-infection was 12%.

    “The mean prevalence of bacterial co-infection was 12% in studies of hospitalised patients not requiring ICU”
    • Also stated in: § Bacterial co-infection reported among hospitalised cases of influenza A(H1N1)pdm09, not requiring ICU · plain
      “any positive bacterial growth was reported in 1.6–76% cases (mean bacterial 12%, Streptococcus pneumoniae 33%).”
    Quote in the paperNot a substantial claim
  • Findingown data

    Streptococcus pneumoniae was the most common bacteria identified in secondary bacterial infections in the 2009 influenza pandemic.

    “with Streptococcus pneumoniae the most common bacteria identified.”
    Quote in the paperSubstantial claim
  • Findingcitation

    In a Canadian study (N=168), secondary bacterial infection was attributed as a leading cause of death in the 29 (17.3%) fatalities.

    “A Canadian study (N = 168) attributed secondary bacterial infection as a leading cause of death in the 29 (17.3%) fatalities that occurred in this cohort [33].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] Kumar A, Zarychanski R, Pinto R, et al. Critically ill patients with 2009 influenza A(H1N1) infection in Canada. JAMA. 2009;302:1872–9. source

      Not checked in the free run.

  • Findingown data

    Among hospitalised A(H1N1)pdm09 cases with confirmed pneumonia and positive bacterial testing, Streptococcus pneumoniae was the most commonly isolated pathogen, at 54%.

    “Streptococcus pneumoniae 54%”
    • Also stated in: § Bacterial co-infection among hospitalised cases of A(H1N1)2009pdm with confirmed pneumonia · plain
      “Streptococcus pneumoniae was the most commonly isolated pathogen (54%).”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 16
  • May combine two claims. 11

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Seventy-five studies met the inclusion criteria for the systematic review.

    “Seventy five studies met the inclusion criteria.”
    • Also stated in: § Summary of included studies · plain
      “75 studies met the inclusion criteria.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    In a large study in Argentina (n=337), 24% of ICU patients with ILI and ARF requiring mechanical ventilation had bacterial pneumonia on admission, and 8% had S. pneumoniae.

    “In a large study involving admissions to 35 ICUs for ILI and ARF requiring mechanical ventilation in Argentina (n = 337), 24% of included patients had bacterial pneumonia on admission, 8% with S. pneumoniae [5].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] Estenssoro E, Rios FG, Apezteguia C, et al. Pandemic 2009 influenza A in Argentina: a study of 337 patients on mechanical ventilation. Am J Respir Crit Care Med. 2010;182:41–8. source

      Not checked in the free run.

  • May combine two claims.

    Findingcitation

    In a study in Argentina, bacteria were found in 76% of nasopharyngeal samples (152/199), of which Streptococcus pneumoniae was isolated in 31% (62/199).

    “Palacios et al. conducted a study in Argentina and bacteria was found in 76% of nasopharyngeal samples (152/199), of which Streptococcus pneumoniae was isolated in 31% (62/199) samples [42].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [42] Palacios G, Hornig M, Cisterna D, et al. Streptococcus pneumoniae coinfection is correlated with the severity of H1N1 pandemic influenza. PLoS One. 2009;4:1–5. source

      Not checked in the free run.

  • May combine two claims.

    Findingcitation

    Of the eight autopsy case series, three studies tested lung tissue specimens for evidence of bacterial infection in all included subjects and identified bacterial co-infection in between 29 and 43% of fatal cases.

    “Of the eight autopsy case series, 3 studies tested lung tissue specimens for evidence of bacterial infection in all included subjects [16–18] and identified bacterial co-infection diagnosed either before or after death in between 29 and 43% of fatal cases [16–18].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [16] Centers for Disease Control and Prevention. Bacterial coinfections in lung tissue specimens from fatal cases of 2009 pandemic influenza A (H1N1) - United States, May–August 2009. MMWR Morb Mortal Wkly Rep. 2009;58:1071–4.

      Not checked in the free run.

    • cites [17] Mauad T, Hajjar LA, Callegari GD, et al. Lung pathology in fatal novel human influenza A (H1N1) infection. Am J Respir Crit Care Med. 2010;181:72–9. source

      Not checked in the free run.

    • cites [18] Shieh W-J, Blau DM, Denison AM, et al. 2009 pandemic influenza A (H1N1): pathology and pathogenesis of 100 fatal cases in the United States. Am J Pathol. 2010;177:166–75. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    It was not clear in many studies if pneumonia was community or hospital acquired.

    “It was not clear in many studies if pneumonia was community or hospital acquired.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In these 9 studies, Acinobacter baumanii was the next most commonly identified bacteria (5-21%), followed by MRSA (3-6%), S. pneumoniae (2-4%) and K. Pneumonia in (1-8%).

    “In these 9 studies, Acinobacter baumanii was the next most commonly identified bacteria (5–21%), followed by MRSA (3–6%), S. pneumoniae (2–4%) and K. Pneumonia in (1–8%).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    In the Korean study of standardised case reports of A(H1N1)pdm09-associated deaths, the estimated ILI case-fatality rate was 16 per 100,000 cases.

    “The Korean study of standardised case reports of A(H1N1)pdm09-associated deaths identified during a period of active surveillance estimated ILI case-fatality rate to be 16 per 100,000 cases [20].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20] Kim HS, Kim JH, Shin SY, et al. Fatal cases of 2009 pandemic influenza A (H1N1) in Korea. J Korean Med Sci. 2011;26:22–7. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    The mPCR assay did not test for S. pneumoniae in one study and the authors could not report the presence of this organism.

    “However, the mPCR assay did not test for S. pneumoniae in one study and the authors could not report the presence of this organism [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] Perez-Padilla R, De La Rosa-Zamboni D, Ponce De Leon S, et al. Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Engl J Med. 2009;361:680–9. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Eleven studies included only PCR confirmed A(H1N1)pdm09 cases, while three included probable cases and another three included both probable and suspected cases.

    “Eleven studies included only PCR confirmed A(H1N1)pdm09 cases, while three included probable cases [31, 39, 40] and another three included both probable and suspected cases [5, 33, 34].”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Almost all studies of hospitalised cases not requiring ICU include patients admitted to general wards, however some were transferred to ICU during the course of treatment.

    “Almost all studies include patients admitted to general wards, however some were transferred to ICU during the course of treatment.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Criteria for admission to ICU varied in the included studies.

    “Criteria for admission to ICU varied in the included studies, including acute respiratory distress (ARD) [26, 27], acute respiratory failure [28, 29], required mechanical ventilation (MV) [5, 30, 31] or MV or low O2/IV vasoconstrictive drugs [32, 33], MV or ECMO [34] or admitted with no criteria provided [35–41].”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Probable cases (13/75 studies) included those with positive influenza A serology during 2009-2010, but not testing of subtype.

    “Probable cases (13/75 studies) included those with positive influenza A serology during 2009–2010, but not testing of subtype.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    The study conducted in Mexico early in the pandemic isolated ventilator-associated bacteria in 4 (22%) cases, with Acinetobacter baumannii, Achromobacter xylosoxidans, methicillin-resistant Staphylococcus aureus, and Escherichia coli identified.

    “The study conducted in Mexico early in the pandemic [23] isolated ventilator-associated bacteria in 4 (22%) cases, with Acinetobacter baumannii, Achromobacter xylosoxidans, methicillin-resistant Staphylococcus aureus, and Escherichia coli identified.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] Perez-Padilla R, De La Rosa-Zamboni D, Ponce De Leon S, et al. Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Engl J Med. 2009;361:680–9. source

      Not checked in the free run.

  • May combine two claims.

    Findingnone given

    Rates of bacterial infection were higher in adults, ICU patients, and those with a fatal outcome.

    “with higher rates in adults, ICU patients and those with a fatal outcome”
    • Also stated in: § Conclusion · hedged
      “with higher rates in adults, ICU patients and those with a fatal outcome”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The prevalence of bacterial co-infection was lower in studies of hospitalized patients not requiring ICU and in studies of paediatric hospitalized patients, although the latter was quite varied.

    “The prevalence of bacterial co-infection was lower in studies of hospitalized patients not requiring ICU and in studies of paediatric hospitalized patients, although the latter was quite varied.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews (PRISMA).

    “A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews (PRISMA) [12].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] Moher D, Liberati A, Tetzlaff J, Altman DG, Group P. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Int J Surg. 2010;8:336–41. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All potentially relevant papers were read by two reviewers to determine those which met the selection criteria.

    “All potentially relevant papers were read by two reviewers (AH, MB) to determine those which met the selection criteria.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Five reviewers independently reviewed titles and abstracts to identify potentially relevant papers.

    “Five reviewers (AH, MB, RT, IR,, HS,) with experience in conducting systematic reviews independently reviewed the titles and abstracts to identify potentially relevant papers.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Pneumonia, hospital admission and ICU admission were accepted according to classification in the reviewed papers.

    “Pneumonia, hospital admission and ICU admission were accepted according to classification in the reviewed papers.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Bacterial pathogens in the respiratory tract may also predispose to influenza and other viral infection.

    “Conversely, bacterial pathogens in the respiratory tract may also predispose to influenza and other viral infection [9].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] Madhi SA, Klugman KP. A role for Streptococcus pneumoniae in virus-associated pneumonia. Nat Med. 2004;10:811–3 Epub 2004/07/13. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Discrepancies between reviewers were discussed with an independent senior reviewer.

    “All findings, including discrepancies between reviewers were discussed with an independent senior reviewer (CRM).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    Each study was independently data extracted by two reviewers.

    “To ensure consistency in data extraction, each study was independently data extracted by two reviewers.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A UK study showed a "w" shaped morbidity curve with a peak in young adults.

    “a UK study showed a “w” shaped morbidity curve with a peak in young adults [46]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [46] Myles PR, Semple MG, Lim WS, et al. Predictors of clinical outcome in a national hospitalised cohort across both waves of the influenza A/H1N1 pandemic 2009–2010 in the UK. Thorax. 2012;67:709–17. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The average age of death in fatal cases during the 2009 pandemic was 53 years, compared to 83 years during seasonal influenza.

    “a low average age of death in fatal cases (53 years compared to 83 years during seasonal influenza) and high intensive care unit (ICU) occupancy rates [45]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [45] Bishop JF, Murnane MP, Owen R. Australia’s winter with the 2009 pandemic influenza A (H1N1) virus. N Engl J Med. 2009;361:2591–4 Epub 2009/11/27. source

      Not checked in the free run.

24 of 24

  • The paper relies on this without support.

    The association between bacterial complications and serious outcomes is causal, such that preventing or treating bacterial secondary infection would reduce death and ICU admission.

    “Bacterial complications were associated with serious outcomes such as death and admission to intensive care. Prevention and treatment of bacterial secondary infection should be an integral part of pandemic planning, and improved uptake of routine pneumococcal vaccination in adults with an indication may reduce the impact of a pandemic.”

  • The paper relies on this without support.

    Bacterial pneumonia cannot always be differentiated from viral pneumonia on the basis of clinical presentation, radiology and routine blood tests.

    “bacterial pneumonia cannot always be differentiated from viral pneumonia on the basis of clinical presentation, radiology and routine blood tests”

  • The paper relies on this without support.

    Currently there are limited data on bacterial coinfection during influenza pandemic in 1918.

    “Currently there are limited data on bacterial coinfection during influenza pandemic in 1918.”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Bacterial complications increased morbidity and mortality of influenza infection.

    “Epidemiological data indicated that bacterial complications further increased morbidity and mortality of influenza infection.”

    From Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection (2020) · cites this paper as MacIntyre et al., 2018

  • During the 2009 influenza pandemic, almost one in four patients presented bacterial complications.

    “During the 2009 influenza pandemic, almost one in four patients presented bacterial complications (MacIntyre et al., 2018).”

    From Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection (2020) · cites this paper as MacIntyre et al., 2018

  • Bacterial complications were an important complication of the 2009 influenza pandemic.

    “bacterial complications were an important complication of the 2009 influenza pandemic (MacIntyre et al., 2018).”

    From Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection (2020) · cites this paper as MacIntyre et al., 2018

  • Similar to SARS, conditional pathogens were the most common infectious microbes in influenza.

    “Similar to SARS, conditional pathogens were the most common infectious microbes (Muscedere et al., 2013; MacIntyre et al., 2018).”

    From Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection (2020) · cites this paper as MacIntyre et al., 2018

  • In the 2009 influenza pandemic, 1 in 4 severe or fatal cases of influenza A(H1N1)pdm09 had a bacterial infection.

    “In the 2009 influenza pandemic, 1 in 4 severe or fatal cases of influenza A(H1N1)pdm09 had a bacterial infection, with an apparent association with morbidity and mortality.”

    From Co-infections in people with COVID-19: a systematic review and meta-analysis. (2020) · cites this paper as [43]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

  • Zero pneumococcal cases are labelled 100%

    Major

    The Choi row reports zero cases among 17 patients but labels this as 100%. The percentage is 0%.

    Reported 100 · recomputed 0

  • Zero bacterial-positive cases are labelled 19%

    Major

    The Koegelenberg row reports 0 of 19 patients with positive bacterial growth but gives a rate of 19%. The rate is 0%.

    Reported 19 · recomputed 0

  • Paediatric pneumonia percentage does not match its count

    Minor

    The Kumar row gives 23 of 75 patients with pneumonia, which is 30.7%, not 34.3%.

    Reported 34.3 · recomputed 30.666667

  • All Shin patients admitted to ICU are labelled 0%

    Minor

    The paediatric table lists 30 of 30 patients as requiring ICU but gives the percentage as 0%.

    Reported 0 · recomputed 100

  • Kumar invasive-ventilation percentage uses a different denominator

    Minor

    The reported 94.1% corresponds to 128 of the 136 mechanically ventilated patients. With the printed denominator of 168, the percentage is 76.2%.

    Reported 94.1 · recomputed 76.190476

  • Torres bacterial-positive percentage is understated

    Minor

    One positive case among 11 patients is 9.1%, not 0.9%.

    Reported 0.9 · recomputed 9.090909

  • Miller death percentage is understated

    Minor

    Eight deaths among 47 patients is 17.0%, not 14%.

    Reported 14 · recomputed 17.021277

  • Rice invasive-ventilation percentage uses a different denominator

    Minor

    The printed denominator gives 175 of 683 patients, or 25.6%, not 75.8%. The reported percentage instead corresponds to 175 of the 231 mechanically ventilated patients; the adjacent noninvasive-ventilation figure has the same denominator mismatch.

    Reported 75.8 · recomputed 25.622255

  • Miller invasive-ventilation denominator conflicts with its percentage

    Minor

    The reported 84.6% corresponds to 11 of the 13 mechanically ventilated patients, not the printed denominator of 47. Eleven of 47 is 23.4%.

    Reported 84.6 · recomputed 23.404255

  • Fatal-case ventilation percentage uses the wrong denominator

    Minor

    The table reports 25 of 47 cases requiring mechanical ventilation, which is 53.2%, not 80.6%.

    Reported 80.6 · recomputed 53.191489

  • Kim ventilation percentage is labelled 100%

    Minor

    The row reports mechanical ventilation for 162 of 245 patients, or 66.1%, rather than 100%.

    Reported 100 · recomputed 66.122449

  • Champunot death percentage is understated

    Minor

    Five deaths among 24 patients is 20.8%, not 8.3%.

    Reported 8.3 · recomputed 20.833333

  • Randolph ventilation percentage uses a different denominator

    Minor

    The row reports mechanical ventilation for 546 of 838 patients, or 65.2%, rather than 67.3%.

    Reported 67.3 · recomputed 65.155131

  • Roch ventilation percentage uses the wrong denominator

    Minor

    Ten of 18 patients is 55.6%, not the reported 100%.

    Reported 100 · recomputed 55.555556

14 of 14

The citation lists haven’t been fetched yet

References 95 · Cited by 323

Research works printed but not linked: 3

  1. World Health Organisation (WHO). WHO guidelines on the use of vaccines and antivirals during influenza pandemics. 2004.
  2. Bonten M, Bolkenbaas M, Huijts S, et al. Community acquired pneumonia immunisation trial in adults (CAPITA). Pneumonia. 2014;3:95.
  3. Itzwerth R. Pandemic influenza and critical infrastructure. Sydney: University of New South Wales (UNSW); 2013.

Authors
MacIntyre, C. R., Chughtai, A. A., Barnes, M., Ridda, I., Seale, H., Toms, R., & Heywood, A.
Affiliations
UNSW Sydney (AU)
Corresponding author
Chughtai, Abrar Ahmad
ORCID
Venue
BMC Infectious Diseases
Publisher
Springer Science and Business Media LLC
Published
2018-12
Volume
18
Issue
1
Pages
637-637
ISSN
1471-2334 (ISSN-L)
DOI
10.1186/s12879-018-3548-0
PMC
PMC6286525
OpenAlex
W2904662596
Semantic Scholar
4d4b190eef71b868c0a593be894c4cdbe3d5012c
Cited by
323
References
95
Citations by year
2026: 12 · 2025: 13 · 2024: 38 · 2023: 48 · 2022: 59 · 2021: 73 · 2020: 72 · 2019: 8
FWCI
29.74
Type
journal article
Language
en
Open access
Licence
Locations
  • BMC Infectious Diseases (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • UNSWorks (University of New South Wales, Sydney, Australia) (submittedVersion, cc-by-nc-nd)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Topics
  • Health Sciences › Medicine › Epidemiology › Influenza Virus Research Studies
  • Health Sciences › Medicine › Epidemiology › Pneumonia and Respiratory Infections
  • Health Sciences › Medicine › Epidemiology › Respiratory viral infections research
Keywords
influenza A(H1N1)pdm09, 2009 H1N1 pandemic, secondary bacterial infection, pneumonia, Streptococcus pneumoniae, bacterial co-infection, fatal outcome, intensive care unit admission, pediatric patients, pneumococcal vaccination, bacterial complications
MeSH terms
Adult, Bacterial Infections, Child, Humans, Influenza, Human, Mortality, Pneumonia, Severity of Illness Index, Prevalence, History, 21st Century, Influenza A Virus, H1N1 Subtype, Pandemics, Coinfection

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

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Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

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