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What Is The Cepheid 4-Plex And How Does It Work?

The Cepheid 4-Plex is a diagnostic test that simultaneously detects four respiratory pathogens: SARS-CoV-2, influenza A, influenza B, and respiratory syncytial virus (RSV).1

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The Covid-19 pandemic introduced a new and deadlier virus to a world dominated by other less harmful viruses of the same or related virus family. Often presenting with similar clinical signs and symptoms, it can be difficult to tell whether an individual has Covid-19 or the run-of-the-mill flu. The Cepheid 4-Plex test solves this dilemma by detecting and differentiating four different virus strains that often present with similar symptoms and can be easily misdiagnosed, ensuring an individual receives the proper treatment on time. Let’s take a closer look at this innovative test.

What is the Cepheid 4-Plex test?

Cepheid 4-Plex (Xpert® Xpress SARS-CoV-2/Flu/RSV) is a real-time molecular test that simultaneously detects and differentiates SARS-CoV-2 (Covid-19 virus), influenza A (Flu A), influenza B (Flu B), and respiratory syncytial virus (RSV).

The test, developed and manufactured by Cepheid, is approved by the FDA for use only under the Emergency Use Authorization (EUA), a regulatory mechanism to facilitate the availability and use of medical countermeasures, including vaccines, during public health emergencies. Currently, the test can only be administered by a medical professional and is limited to CLIA-certified laboratories or portable lab equipment that meet requirements to perform high or moderate complexity tests.

How does this test detect and differentiate all four viruses?

SARS-CoV-2 (Covid-19 virus), influenza A, influenza B, and respiratory syncytial virus (RSV) are considered RNA viruses because they contain RNA as their genetic material. When any of these viruses infect an individual, they inject this RNA into the body’s healthy cells, tricking them into manufacturing more copies of the virus.

At the peak of the infection, the body has an abundance of virus RNA, which the Cepheid 4-Plex targets and tests. As a real-time reverse transcription polymerase chain reaction (RT-PCR) test, it detects the virus RNA and uses nucleic acid amplification techniques to sequence and identify the virus.

Since all four viruses have unique RNA data (similar to DNA in uniqueness), the test can rapidly detect and differentiate which virus is present in the sample, providing a conclusive diagnosis.

If an individual suspects that they might have Covid-19, the test can help detect all four types of infection, either ruling out Covid-19 or confirming it.

If ruled out, the individual can avoid various Covid-19 sanctions like self-isolation and quarantine, and if confirmed, the doctor can recommend appropriate treatment, precautions, and quarantining measures.

Cepheid 4-Plex vs. individual tests for each virus

The primary advantage of the Cepheid 4-Plex is the convenience of simultaneously testing for four viruses and getting the results in half an hour. However, at a diagnostic level, the importance of the combined test becomes more apparent.

When testing Covid-19 alone (or any of the other three viruses), ruling it out when an individual has clinical signs and symptoms can present diagnostic ambiguity. In such cases, the doctor will order additional tests, which can amount to higher testing and time costs by the time a conclusive diagnosis emerges.

Requesting the Cepheid 4-Plex test can quickly identify or rule out the four viruses at once, saving both time and money while allowing for faster diagnosis.

Are there any disadvantages to this test?

One disadvantage of the combined test is that a positive or negative result does not always tell the whole story, as other pathogens like bacteria and other viruses might be present but undetected.

As such, the doctor will likely combine the test with clinical observation, patient history, and epidemiological information to arrive at a more accurate diagnosis.

When should you get the Cepheid 4-Plex test?

Getting the combined test can be helpful in cases where an individual is concerned that they might have Covid-19, which might endanger someone in a vulnerable group.

  • If you have flu-like symptoms, the test can tell you whether you have the common flu or the Covid-19 virus, providing context on what to do next to protect yourself and those around you.
  • The test can also help rule out all four viruses and lead to further investigation if the symptoms persist.
  • The Cepheid 4-Plex test is also recommended when an individual had Covid-19 before and recovered but has developed flu-like symptoms. In such cases, the combined test can quickly determine whether they have become reinfected or another virus presenting with similar clinical signs and symptoms might be the cause.

How in-home Cepheid 4-Plex testing works

When you book an in-home Cepheid 4-Plex test with Drip Hydration, a registered nurse will arrive at the appointed time to administer the test.

After collecting your sample, usually through a nasal swab, they will input it into a portable cartridge-based testing console that will detect and interpret the sample within thirty minutes. The nurse will then give you the results and offer further guidance if the test results are positive for any of the four viruses.

If the test results are negative yet you have symptoms, they may recommend that you see a doctor who may recommend further tests to identify the cause of your symptoms.

Get An In-home Cepheid 4-Plex Test Today (Selected Locations Only)

In-home Cepheid 4-Plex testing is a fast way to get tested while avoiding the inconvenience of going to a clinic. If you are feeling unwell, in-home testing also allows you to get tested as you rest and recover in the comfort of your home.

Drip Hydration offers in-home testing with Cepheid 4-Plex that meets the highest regulatory standards. All our tests are administered and interpreted by a registered nursing practitioner according to FDA and state health rules. Currently, Drip Hydration provides in-home Cepheid 4-Plex testing services in the following locations:

  • Atlanta
  • Connecticut
  • Miami
  • Fresno-Clovis
  • Inland Empire
  • Los Angeles
  • Miami
  • New Jersey
  • New York City
  • Orange County
  • Palo Alto
  • Palm Springs
  • Raleigh-Durham
  • San Diego
  • San Francisco
  • Santa Barbara
  • Seattle
  • Washington DC

Click the button below to book an in-home Cepheid 4-Plex test today.


[1] Mostafa HH, Carroll KC, Hicken R, Berry GJ, Manji R, Smith E, Rakeman JL, Fowler RC, Leelawong M, Butler-Wu SM, Quintero D, Umali-Wilcox M, Kwiatkowski RW, Persing DH, Weir F, Loeffelholz MJ. Multicenter Evaluation of the Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV Test. J Clin Microbiol. 2021 Feb 18;59(3):e02955-20. doi: 10.1128/JCM.02955-20. PMID: 33298613; PMCID: PMC8106732.;