Duration of viral shedding in patients admitted to hospital with pandemic influenza A/H1N1 2009 infection.
Little is known about the kinetics of viral shedding of pandemic influenza A/H1N1 2009 virus. Influenza RNA, as a surrogate for viral clearance, was therefore measured on days 1, 5, 7, and 10 or more in patients admitted to hospital with pandemic influenza A/H1N1 2009 infection. A total of 72 patients who were admitted to hospital with confirmed pandemic influenza A/H1N1 2009 at a tertiary care hospital, Seoul, South Korea, between 1 September and 11 November 2009 were evaluated. The median duration of viral shedding, as assessed by RT-PCR, was 9 days, as determined by the Kaplan-Meier method. Patients who were positive by RT-PCR at their last assay, but who were discharged before the next RT-PCR test due to symptom improvement, were censored from the analysis. If such patients were included, with the assumption that they had negative viral status at discharge, the median duration of viral shedding was 5 days (interquartile range, 2-8 days). These calculations thus suggest that the true median duration of viral shedding is between 5 and 9 days. Univariate analysis showed that delayed administration of antiviral therapy and comorbidity were associated with slower viral clearance. Multivariate analysis showed that oseltamivir started after the first day of symptoms (OR 2.7, 95% CI 1.2-5.7) was associated independently with slower viral clearance. These findings indicate that, in about 50% of patients admitted to hospital with pandemic influenza A/H1N1 2009, virus can be positive as tested by RT-PCR on the eighth day after developing symptoms of influenza. The present findings also indicate that starting antiviral therapy within 24 hr of the onset of symptoms is associated with more rapid viral clearance.
Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Shin
S
Na
Yong Pil
YP
Chong
Mi-Na
MN
Kim
Won Young
WY
Kim
Won
W
Kim
Sang-Bum
SB
Hong
Chae-Man
CM
Lim
Younsuck
Y
Koh
Ji-Won
JW
Kwon
Soo-Jong
SJ
Hong
Sang-Oh
SO
Lee
Sang-Ho
SH
Choi
Yang Soo
YS
Kim
Jun Hee
JH
Woo
Sung-Han
SH
Kim
D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000008:administration & dosage; D006760:Hospitalization; D006761:Hospitals; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000188:drug therapy / Q000473:pathology / Q000821:virology*; D008875:Middle Aged; D010614:Pharynx / Q000821:virology; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D056910:Republic of Korea; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D017201:Virus Shedding
D000998:Antiviral Agents; D012367:RNA, Viral