Rate and influence of respiratory virus co-infection on pandemic (H1N1) influenza disease

Frank P. Esper, Timothy Spahlinger, Lan Zhou

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Objectives: Many patients with influenza have more than one viral agent with co-infection frequencies reported as high as 20%. The impact of respiratory virus copathogens on influenza disease is unclear. We sought to determine if respiratory virus co-infection with pandemic H1N1 altered clinical disease. Methods: Respiratory samples from 229 and 267 patients identified with and without H1N1 influenza respectively were screened for the presence of 13 seasonal respiratory viruses by multiplex RT-PCR. Disease severity between coinfected and monoinfected H1N1 patients were quantified using a standardized clinical severity scale. Influenza viral load was calculated by quantitative RT-PCR. Results: Thirty (13.1%) influenza samples screened positive for the presence of 31 viral copathogens. The most prominent copathogens included rhinovirus (61.3%), and coronaviruses (16.1%). Median clinical severity of both monoinfected and coinfected groups were 1. Patients coinfected with rhinovirus tended to have lower clinical severity (median 0), whereas non-rhinovirus co-infections had substantially higher clinical severity (median 2). No difference in H1N1 viral load was observed between coinfected and monoinfected groups. Conclusions: Respiratory viruses co-infect patients with influenza disease. Patients coinfected with rhinovirus had less severe disease while non-rhinovirus co-infections were associated with substantially higher severity without changes in influenza viral titer.

Original languageEnglish (US)
Pages (from-to)260-266
Number of pages7
JournalJournal of Infection
Issue number4
StatePublished - Oct 2011


  • Co-infection
  • Dual infection
  • Influenza
  • Influenza co-infection
  • Pneumonia
  • Respiratory disease
  • Respiratory virus co-infection
  • Viral co-infection

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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