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Pneumonia, Viral
R. Aaron Lambert, MD
image BASICS
  • Inflammatory disease of the lungs due to a viral infection
  • Most viral pneumonia results from exposure infection in the form of aerosolized secretions.
  • Hematogenous and direct spread are also possible.
Geriatric Considerations
High rates of morbidity and mortality in the elderly
Pediatric Considerations
  • Adenoviral infections in children are serious.
  • More serious respiratory viral infections are almost always seen in infants and in immunocompromised patients.
Pregnancy Considerations
  • Pregnant patients should avoid contact with anyone who has a viral infection.
  • Influenza vaccination is recommended for all pregnant women during the influenza season.
  • Predominant age: children <5 years
  • Predominant sex: male = female
  • Prevalence is variable with seasonal outbreaks, but the disease is more common during winter months.
  • ˜90% of all cases of childhood pneumonias have a viral cause.
  • Between 4% and 39% of pneumonia diagnosed in adults has been attributed to viral causes.
Overall: Influenza A and respiratory syncytial virus (RSV) are the leading causes followed by adenovirus and the parainfluenza viruses:
  • Adults
    • Influenza A, B, and C
    • Influenza H1N1
    • Adenovirus
    • Parainfluenza
    • Coronavirus/SARS
  • Children
    • Influenza A, B, and C
    • Influenza H1N1
    • Rhinovirus
    • Adenovirus
    • Parainfluenza
    • Rubeola (measles)
    • RSV (particularly for those born prematurely)
  • Miscellaneous
    • Cytomegalovirus (CMV) (particularly in immunocompromised patients)
    • Varicella
    • Herpes simplex virus (HSV)
    • Enterovirus
    • Rubeola
    • Epstein-Barr virus
    • Hantavirus
    • Human metapneumovirus
No known genetic pattern has been recognized.
  • Seasonal: epidemic upper respiratory illness
  • Living in close quarters
  • Recent upper respiratory infection
  • Travel to endemic area
  • Nonvaccinated person
  • Age >65 years or <5 years
  • Altered mental status (due to dysphagia)
  • Cardiac disease
  • Chronic pulmonary disease (e.g., COPD, emphysema)
  • Immunocompromised (HIV, transplant recipient, medication-induced)
  • Cystic fibrosis
  • Kartagener syndrome
  • General hand-hygiene techniques are the first-line prevention in transmission of infectious particles.
  • Influenza vaccination: Routine vaccination is now recommended for ALL persons aged ≥6 months.
    • Children who are 6 months to 8 years of age and receiving seasonal vaccination for the first time should receive two doses 4 weeks apart.
    • Children who are 6 months to 8 years of age who received two doses of the influenza vaccine should receive one dose of the seasonal influenza vaccine the following year.
    • See the CDC guidelines (1)[A] regarding the use of live attenuated vaccine versus inactivated vaccine.
  • For those patients who are unable to receive influenza vaccine (e.g., with an egg allergy or other) and are at very high risk because of age, comorbid illness, or another risk factor, oseltamivir or zanamivir may be used for the duration of the season, with special recognition for potential viral resistance.
  • For those who did not receive the vaccine and have been exposed to influenza, use of oseltamivir or zanamivir is recommended for up to 10 days following exposure.
  • Rate of mixed viral-bacterial coinfection is ˜20% and can lead to more severe illness or hospitalization.
  • Fungal infection and Pneumocystis jiroveci pneumonia in immunocompromised patients
  • Fever
  • Tachypnea
  • Tachycardia
  • Hypoxemia with severe disease
  • Altered breath sounds (bronchophony, tactile fremitus, whispered pectoriloquy)
  • Pulmonary rales and rhonchi
  • Friction rub
  • Possible associated rash (i.e., measles, HSV)
  • Bacterial pneumonia (especially atypical etiologies: Chlamydophila pneumoniae and C. psittaci, Mycoplasma pneumoniae, Legionella pneumophila)
  • Pulmonary edema
  • Pneumocystis pneumonia/P. jiroveci pneumonia
  • Aspiration pneumonia
  • Hypersensitivity pneumonitis
  • Bronchiolitis obliterans, with organizing pneumonia
  • Pulmonary embolus/infarction
  • Cystic fibrosis (in infants)
  • Severe acute respiratory syndrome or severe acute respiratory syndrome-associated coronavirus
  • No standard labs to diagnose viral pneumonia
  • Specific lab investigations should be based on the clinical scenario.
Initial Tests (lab, imaging)
  • CBC
    • Normal or near-normal granulocyte count, occasionally leukopenic with increased lymphocyte percentage
    • Hemoconcentration (hantavirus)
  • Chest x-ray (CXR)
    • interstitial or alveolar infiltrates
    • peribronchial thickening
  • Ground-glass opacities (GGO) are predictive (OR 4.68) (2)[B].
  • ESR/CRP may be helpful in children.
Follow-Up Tests & Special Considerations
Clinicians can also consider additional testing, as clinically indicated:
  • Appropriate direct fluorescent antibody or enzyme immunoassay from throat nasopharyngeal washings (children) or swab (adults), tracheal aspirate, or bronchoalveolar lavage specimens (HSV, varicella-zoster virus, influenza viruses A and B, RSV, adenovirus)
  • P.817

  • Viral culture
    • Limitations: Results take 3 to 14 days. False-negative results occur with lower viral titers.
    • Rapid antigen detection: nasopharyngeal swab for rapid influenza testing
    • Cytopathology (cytoplasmic inclusion bodies [CMV], HSV, measles virus)
    • Serology (4-fold rise in acute compared with convalescent titers): Confirm diagnosis retrospectively but not clinically useful.
    • Serologic testing for hantavirus: enzyme immunoassay if available from health departments
    • Polymerase chain reaction (PCR) detection if modality is available:
      • Highly sensitive and specific, but a positive result does not imply causality.
  • Sputum Gram stain and culture to identify bacterial copathogens, if present
  • Chest CT may show consolidations surrounded by GGOs.
Diagnostic Procedures/Other
Bronchoscopy with bronchoalveolar lavage
  • Outpatient treatment for most patients
  • Inpatient treatment for infants <4 months of age, elderly or for any patient with diffuse, severe infection (e.g., hypoxemia, hypercarbia, hypotension or shock, acute respiratory distress syndrome [ARDS]) or significant comorbidity (e.g., congestive heart failure [CHF], coronary artery disease, COPD)
  • The Pneumonia Severity Index Calculator (3)[A] (http://www.mdcalc.com/psi-port-score-pneumonia-severity-index-adult-cap/) may be used to assess the need for hospitalization as well as mortality risk.
  • Consider concomitant treatment for bacterial coinfection if severely ill or not responding to treatment.
First Line
  • Influenza viruses A and B
    • Oseltamivir (Tamiflu): adults and children >40 kg, 75 mg PO q12h for 5 days; dosage is adjusted to 75 mg PO q24h in cases where creatinine clearance rate is <30 mL/min. Children <40 kg, weight-based effectiveness is maximal when started within 48 hours of symptom onset.
    • Zanamivir (Relenza): patients >7 years of age, 2 inhalations (10 mg) q12h for 5 days
      • Shown to shorten symptoms by ˜12 hours but not risk of complications (4)[B]
  • Varicella-zoster virus
    • Acyclovir
      • Adults: for immunocompetent patients, 800 mg PO 5 times per day for 5 to 7 days
      • Children >2 years: for immunocompetent patients, 80 mg/kg/day PO divided q6h for 5 days. Start within 24 hours of symptom onset; immunocompromised patients 30 mg/kg/day PO divided q6h for 5 days. Start within 24 hours of symptom onset; immunocompromised patients 30 mg/kg/day IV divided q8h for 7 to 10 days.
  • CMV or HSV
    • Acyclovir
      • Immunocompromised adults: 5 mg/kg IV q8h for 7 days
      • Children: Contact an infectious disease specialist or an experienced pharmacist regarding dosing.
    • Ganciclovir: Use should be in conjunction with infectious disease consultation.
  • RSV
    • Ribavirin: Indicated in few, select cases (20 mg/mL via continuous aerosol administration for 12 to 18 hr/day for 3 to 7 days). Ribavirin is teratogenic and should not be administered by pregnant health care personnel: Its cost is high and benefits are marginal.
Second Line
  • Influenza: Amantadine and rimantadine are no longer recommended due to high levels of resistance among circulating influenza A viruses (5)[B].
  • Influenza: Peramivir 600 mg for 1 dose is an IV formulation available for acute illness in hospitalized patients (1).
  • CMV, HSV, varicella virus infections
    • Foscarnet (Foscavir): 60 mg/kg/dose IV q8h in conjunction with infectious disease consultation
  • Most healthy individuals will only require symptomatic treatment.
  • Encourage coughing and deep breathing exercises to clear secretions.
  • Careful disposal of secretions/universal precautions.
  • Hydration
  • Respiratory isolation with negative pressure room for varicella virus, which is highly contagious
Patient Monitoring
  • Physical exams
  • Repeat a CXR only if warranted by clinical presentation. A CXR may take weeks to resolve after clinical illness has resolved.
  • Oxygenation if illness severe enough for hospitalization
  • For patient education materials on this topic, contact American Lung Association, 1301 Pennsylvania Avenue, NW, Suite 800, Washington, DC 20004; 800-LUNG-USA
  • Centers for Disease Control and Prevention. Seasonal influenza (flu). http://www.cdc.gov/flu/
  • Usually favorable prognosis, with illness lasting several days to a week
  • Postviral fatigue is common.
  • Death can occur, especially in pediatric or bone marrow transplant recipients with adenovirus infections or in older people with influenza.
  • The 2009 H1N1 influenza pandemic resulted in higher-than-usual mortality rates among the pediatric, young adult, and pregnant populations.
1. Centers for Disease Control and Prevention. Seasonal influenza (flu). http://www.cdc.gov/flu/.
2. Kim JE, Kim UJ, Kim HK, et al. Predictors of viral pneumonia in patients with community-acquired pneumonia. PLoS One. 2014:9(12):e114710.
3. MDCalc. PSI/PORT Score: Pneumonia Severity Index for CAP. http://www.mdcalc.com/psi-port-score-pneumonia-severity-index-adult-cap/. Accessed 2015.
4. Heneghan CJ, Onakpoya I, Thompson M, et al. Zanamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ. 2014;348:g2547.
5. Grohskoph LA, Sokolow LZ, Olsen SJ, et al. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices, United States, 2015-16 influenza season. MMWR Morb Mortal Wkly Rep. 2015;64(30):818-825.
Additional Reading
  • Marcos MA, Esperatti M, Torres A. Viral pneumonia. Curr Opin Infect Dis. 2009;22(2):143-147.
  • Ruuskanen O, Lahti E, Jennings LC, et al. Viral pneumonia. Lancet. 2011;377(9773):1264-1275.
See Also
Bronchiolitis Obliterans and Organizing Pneumonia; Respiratory Distress Syndrome, Acute (ARDS)
  • J12.9 Viral pneumonia, unspecified
  • J12.0 Adenoviral pneumonia
  • J12.1 Respiratory syncytial virus pneumonia
Clinical Pearls
  • Laboratory testing may confirm the diagnosis of viral pneumonia, but this may not change therapy and must not replace clinical judgment.
  • Influenza vaccination is recommended for all persons age ≥6 months.
  • Most patients recover with conservative therapy.
  • Monitor for concomitant bacterial infections.
  • Amantadine and rimantadine are no longer recommended for use against influenza.