What is the prevalence of viral pneumonia?

Updated: Mar 24, 2021
  • Author: Zab Mosenifar, MD, FACP, FCCP; Chief Editor: John J Oppenheimer, MD  more...
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Traditionally, viruses were felt to cause approximately 8% of cases of community-acquired pneumonia for which patients are hospitalized. More recent investigations have demonstrated viruses to play a larger role, causing 13-50% of pathogen-diagnosed community-acquired pneumonia cases as sole pathogens and 8-27% of cases as mixed bacteria-virus infections. [3, 4, 5, 34]

Influenza virus types A and B account for more than 50% of all community-acquired viral pneumonias in adults. Various studies have reported differing frequencies of the other viruses causing community-acquired pneumonias, with RSV ranging from 1-4%, adenovirus 1-4%, PIV 2-3 %, hMPV 0-4%, and coronavirus 1-14% of pathogen-diagnosed pneumonia cases. [3, 4, 5, 34]

The impact of influenza is high in elderly persons and greatest for those with chronic illnesses. It has been estimated that at least 63% of the 300,000 influenza-related hospitalizations and 85% of 36,000 influenza-related deaths occur in patients aged 65 years or older, despite the fact that this group accounts for only 10% of the population. [35]

RSV is the most common etiology of viral pneumonia in infants and children. [36] In addition, RSV has become an increasingly important pathogen in the elderly population and is now the second most commonly identified cause of pneumonia in elderly persons, causing 2-9% of the annual 687,000 hospitalizations and 74,000 deaths from pneumonia in this population. [13]

Some studies have suggested that RSV-related disease is as frequent as influenza in elderly persons. Approximately 10% of nursing home patients develop RSV infection annually, while 10% of these patients will develop pneumonia.

Parainfluenza infection is the second most common viral illness, after RSV, in infants.

Adenovirus accounts for 10% of pneumonias in children. Disease from adenovirus can occur at any time of the year. Various adenovirus serotypes are responsible for essentially continuous epidemics of acute respiratory disease at military recruit training facilities in the United States and worldwide. During the prevaccination era, up to 20% of recruits had to be removed from duty due to illness. [37] Unfortunately, the vaccine against adenovirus is no longer available for administration to military personnel.

In late 2019, a novel coronavirus (2019-nCoV) was identified as the cause of viral pneumonia cases in Wuhan City, Hubei Province, China. See the Medscape Drugs & Diseases article 2019-nCoV Coronavirus for updated information on this outbreak.

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