Diagnosis and Assessment
Table 3. Interpretation of Rapid Influenza Antigen Test
Results on Specimens From Patients With
Influenza-like Illness
Influenza Activity
Positive Predictive Valuea, b
Negative Predictive
Valueb, c
Very low (summer)
Low (early or late season)
High (community outbreaks)
Peak activity
Very low
Low to moderate
High
Very high
Very high
High
Low to moderate
Low
Source: Centers for Disease Control and Prevention. Antiviral Agents for the Treatment and
Chemoprophylaxis of Influenza: Recommendations of the Advisory Committee on Immunization
Practices (ACIP). MMWR Recomm Rep. 2011;60:1-26.
a
Proportion of persons with positive test results who have influenza.
b
Influenced by screening test sensitivity, specificity, and prevalence of influenza (community
influenza activity) in population being tested; assumes median sensitivity of 70%–75%, and
median specificity of 90%–95% compared to viral culture or RT-PCR. Sensitivity in children
(approximately 70%–90%) is much higher than in adults (<40%–60%).
c
Proportion of persons with negative test results who do not have influenza.
Selecting a Treatment Regimena
ÎÎTreatment (Table 4) for high-risk patients is recommended at
symptom onset (A-II).
ÎÎTreatment for high-risk patients is recommended regardless of
influenza vaccination status and regardless of severity of illness (A-II).
ÎÎTreatment is recommended for patients with confirmed or suspected
influenza who are hospitalized and those with severe illness,
regardless of duration of symptoms. Earlier initiation of therapy is
likely to be more effective (B-II).
ÎÎTreatment is also recommended for low-risk outpatients with
laboratory-confirmed or highly suspected influenza virus infection
within 48 hours of presentation who wish to shorten the duration of
illness and further reduce their relatively low risk of complications
(A-I) or who are in close contact with persons at high risk of
complications secondary to influenza infection.
a
4
Based on the IDSA guidelines modified to reflect the 2013 update and theAntiviral Agents for the
Treatment and Chemoprophylaxis of Influenza: Recommendations of the Advisory Committee on
Immunization Practices (ACIP). MMWR Recomm Rep. 2011;60:1-26.
