Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination

Olivia Horga, Mercer University College of Pharmacy

According to the Centers for Disease Control and Prevention (CDC), there were 3,000 to 49,000 flu-associated deaths between 1976 and 2007. During recent flu seasons, it was reported that 80% to 90% of flu-related deaths occurred in people 65 years and older. The CDC recommends an annual seasonal flu vaccine and states that it is the best method of reducing the chances of contracting the seasonal flu and spreading it to others. [1]

According to a review article of 49 studies, primary viral pneumonia is recognized as the most severe pulmonary manifestation of influenza. The article suggests that the morbidity and mortality are significant with viral pneumonia. As a result of their decline in immune response, presence of comorbidities, and greater exposure risk due to living quarters, the elderly are at an even greater risk to develop viral pneumonia. [2]

The American Thoracic Society Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia suggest that the use of an influenza vaccine among at-risk healthcare workers and high-risk patients dramatically reduces the spread of influenza within a hospital and healthcare facilities. [3]

Title: Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination [4]
Design Case-control, prospective, observational, multicenter; N = 5109
Objective To assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia
Study Groups Children and adults admitted with community-acquired pneumonia enrolled at 8 hospitals in 4 sites: Nashville, TN; Memphis, TN; Chicago, IL; Salt Lake City, UT
Methods
  • Nasopharyngeal and oropharyngeal swabs collected to confirm influenza virus infection
    • Case patients – hospitalized for pneumonia whose nasopharyngeal/oropharyngeal swabs collected within 72 hours of admission tested positive for influenza by Reverse Transcription Polymerase Chain Reaction (RT-PCR) with a cycle threshold value of less than 40
    • Control patients – hospitalized for pneumonia who tested negative for influenza
  • Verify vaccination status of patients
Duration January 2010 – June 2012
Primary Outcome Measure Influenza pneumonia, confirmed by real-time (RT-PCR) performed on nasal/oropharygeal swabs
Baseline Characteristics Controls: Noninfluenza Pneumonia

(n = 2605)

Cases: Influenza Pneumonia

(n = 162)

Nonvaccinated

(n = 1973)

Vaccinated

(n = 794)

Children, n 1309 68 994 383
Age, median (IQR), y
Overall 17 (3-55) 31 (5-540) 17 (3-53) 28 (2-65)
Children 3 (1-6) 3 (1-9) 3 (1-7) 3 (1-6)
Adults 55 (44-68) 52.5 (40-63) 53 (41.5-64) 63 (52-74.5)
Female sex, n 1259 73 943 389
Race/ethnicity, n
White 1096 50 771 375
Black 1016 77 858 235
Hispanic 361 25 249 137
Other 132 10 95 47
Chronic conditions, n 1628 91 1159 560
Results Sensitivity Analyses Within Study of Influenza Vaccination and Influenza Pneumonia
Cases Vaccinated, No./Total No. Controls Vaccinated, No./Total No. Adjusted Odds Ratio (95% Confidence Interval [CI]) Estimated Vaccine Effectiveness, % (95% CI)
Overall estimate 28/162 766/2605 0.43 (0.28-0.68) 56.7 (31.9-72.5)
2010-2012 Season 28/156 721/2300 0.44 (0.28-0.69) 56.4 (31.2-72.3)
Groups
Children 7/68 376/1309 0.25 (0.11-0.58) 74.6 (42.5-88.8), p = 0.1
Adults 21/94 390/1296 0.59 (0.34-1.02) 41.5 (−2.2-66.5), p = 0.1
Adverse Events Common Adverse Events: not reported
Serious Adverse Events: not reported
Percentage that Discontinued due to Adverse Events: not reported
Study Author Conclusions Among children and adults hospitalized with community-acquired pneumonia, those with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.

The study summarized above suggests that influenza vaccination is effective in preventing influenza-associated pneumonia. [4]

As a result of increased mortality due to influenza pneumonia, the CDC recommends that eligible individuals should receive an annual influenza vaccine in order to prevent complications such as the development of influenza pneumonia. Although the influenza vaccine cannot fully prevent influenza pneumonia, it can help reduce its incidence. [1]

Pharmacists can take part in improving patient safety by recommending preventative therapies such as annual influenza vaccination.

References

  1. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/protect/keyfacts.htm. Accessed October 26, 2015.
  2. Rello J, Pop-vicas A. Clinical review: primary influenza viral pneumonia. Crit Care. 2009;13(6):235.
  3. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171(4):388-416.
  4. Grijalva CG, Zhu Y, Williams DJ, et al. Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination. JAMA. 2015;314(14):1488-97.
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