Diagnosing COVID-19 and flu

An early, reliable diagnosis may have downstream benefits for patients

Improved testing practices may help healthcare providers:

References: 1. Clark TW, Lindsley K, Wigmosta TB, et al. Rapid multiplex PCR for respiratory viruses reduces time to result and improves clinical care: results of a systematic review and meta-analysis. J Infect. 2023;86(5):462-475. doi:10.1016/j.jinf.2023.03.005 2. Hinson JS, Rothman RE, Carroll K, et al. Targeted rapid testing for SARS-CoV-2 in the emergency department is associated with large reductions in uninfected patient exposure time. J Hosp Infect. 2021;107:35-39. doi:10.1016/j.jhin.2020.09.035 3. Pedersen CJ, Rogan DT, Yang S, Quinn JV. Using a novel rapid viral test to improve triage of emergency department patients with acute respiratory illness during flu season. J Clin Virol. 2018;108:72-76. doi:10.1016/j.jcv.2018.09.008 4. Guide for considering influenza testing when influenza viruses are circulating in the community. Centers for Disease Control and Prevention. Updated November 24, 2023. Accessed April 16, 2024. https://www.cdc.gov/flu/professionals/diagnosis/consider-influenza-testing.htm#:~:text=Influenza 5. Why COVID-19 testing is the key to getting back to normal. National Institute on Aging. Published September 4, 2020. Accessed April 16, 2024. https://www.nia.nih.gov/news/why-covid-19-testing-key-getting-back-normal 6. Shirley JD, Bennett SA, Binnicker MJ. Current regulatory landscape for viral point-of-care testing in the United States. J Clin Virol. 2023;164:105492. doi:10.1016/j.jcv.2023.105492 7. Benirschke RC, McElvania E, Thomson RB Jr, Kaul KL, Das S. Clinical impact of rapid point-of-care PCR influenza testing in an urgent care setting: a single-center study. J Clin Microbiol. 2019;57(3):e01281-18. doi:10.1128/jcm.01281-18

COVID-19, Flu A, and Flu B have similar symptoms, highlighting the importance of multiplex testing^1-3

= Shared symptom

The ability to quickly and reliably detect Flu A, Flu B, and/or COVID-19 can inform approach and initiation of treatment, when appropriate¹

^†Both COVID-19 and flu can present with varying degrees of symptom severity. This is not an all-inclusive list of possible symptoms and symptoms may change with new COVID-19 variants and can vary by person.^1,4

References: 1. Similarities and differences between flu and COVID-19. Centers for Disease Control and Prevention. Updated March 20, 2024. Accessed March 4, 2024. https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm 2. Clinical guidance for hospitalized and non-hospitalized patients when SARS-CoV-2 and influenza viruses are co-circulating. Centers for Disease Control and Prevention. Updated December 6, 2023. Accessed April 16, 2024. https://www.cdc.gov/flu/professionals/diagnosis/testing-guidance-for-clinicians.htm 3. CDC’s influenza SARS-CoV-2 multiplex assay. Centers for Disease Control and Prevention. Updated November 14, 2022. Accessed April 16, 2024. https://www.cdc.gov/coronavirus/2019-ncov/lab/multiplex.html 4. Symptoms of COVID-19. Centers for Disease Control and Prevention. Updated March 15, 2024. Accessed April 10, 2024. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html

IDSA provides recommendations on the use of molecular testing for COVID-19 and flu in outpatient settings^1,2

This summary should not be used to make individual decisions. To see the full recommendations, please visit www.idsociety.org.

LUCIRA^® by Pfizer COVID-19 & Flu Test was not specifically included in the IDSA assessment informing these guidelines. LUCIRA^® by Pfizer COVID-19 & Flu Test did not have a published clinical study in the time period assessed by the IDSA.

COVID-19 Recommendations
^†A conditional recommendation implies that a majority of those in the general population would want the course of action, although many would not.
^‡Lower or higher levels of IDSA confidence are determined by factors such as risk of bias, consistency, precision, dose response, and publication bias. Confidence levels range from high, moderate, low, to very low.

Flu Recommendations
^§An “A” strength of recommendation (strong recommendation) implies good evidence to support the course of action, and a “C” strength of recommendation (weak recommendation) implies poor evidence.
^||A “II” quality of evidence rating (moderate certainty evidence) implies evidence from 1 or more well-designed clinical trials, without randomization; evidence from cohort or case-controlled analytic studies (preferably from >1 center); evidence from multiple time-series; or evidence from dramatic results from uncontrolled experiments. A “III” quality of evidence rating (low certainty evidence) implies evidence from opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
^¶Those experiencing an exacerbation of chronic disease, or with a previous influenza complication who present with influenza-like illness, pneumonia, or nonspecific respiratory illness (eg, cough without fever) if the testing result will influence clinical management.

IDSA, Infectious Diseases Society of America; NAAT, nucleic acid amplification test; RT-PCR, reverse transcription polymerase chain reaction.

References: 1. Hayden MK, Hanson KE, Englund JA, et al. IDSA guidelines on the diagnosis of COVID-19: molecular diagnostic testing. Infectious Diseases Society of America. Published May 6, 2020. Updated September 5, 2023. Accessed April 16, 2024. https://www.idsociety.org/COVID19guidelines/dx 2. Uyeki TM, Bernstein HH, Bradley JS, et al. Clinical practice guidelines by the Infectious Diseases Society of America: 2018 update on diagnosis, treatment, chemoprophylaxis, and institutional outbreak management of seasonal influenza. Clin Infect Dis. 2019;68(6):e1-e47. doi:10.1093/cid/ciy866