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A rapid strep test is a point-of-care test that checks a throat swab for group A Streptococcus (Streptococcus pyogenes) antigen and gives a qualitative result, positive or negative, within minutes. The kind most clinics stock is a lateral flow immunoassay strip, a rapid antigen detection test (RADT). This page explains what the test is, what is physically in a kit, how the strip is built, and how accurate two published sources report it to be.
This page describes products and general information; it is not medical advice.
Who uses it: clinic and urgent care staff who run waived point-of-care tests, buyers who stock those clinics, and students learning how antigen tests are built.
What a rapid strep test is
A rapid strep test detects group A Streptococcus (GAS) antigen in a direct throat swab. In the FDA decision summary for one waived product, the measurand is the GAS carbohydrate antigen, the sample is a direct throat swab, and the format is a qualitative lateral flow chromatographic immunoassay. It reports presence or absence of antigen, not a quantity.
The Cochrane review of these tests in children describes results at the point of care within minutes. Group A strep accounts for roughly 20 to 40 percent of pharyngitis in children, according to the same review, which is why the test is common in clinics that see sore throats.
How the strip works and what is in the kit
The FDA summary for the Healgen Rapid Strep A Antigen Test (CLIA waiver CW240004, parent 510(k) K212623) describes one product’s design. Other products differ, so treat this as one worked example rather than a description of every test.
In this product, a swab goes into extraction buffer prepared from two supplied reagents, and the buffer extracts the antigen. A test strip placed in the solution draws the liquid along by capillary action. If antigen is present, an antibody at the test line (marked T) captures it and produces a pink-red line. A control line (marked C) must always appear; if it does not, the result is invalid. The product has no instrument and no electrical components.
The example kit contains:
- 25 test strips, 25 sterile swabs and 25 extraction tubes
- Reagent A (10 mL, 2M sodium nitrite) and Reagent B (10 mL, 0.2M acetic acid)
- A positive control (non-viable Strep A) and a negative control (non-viable Strep C)
- A package insert, quick reference instructions and 2 tube holders
Types and variants
| Type | Typical setting | Key difference | Source |
|---|---|---|---|
| Rapid antigen detection test (RADT), lateral flow | Point-of-care detection of group A strep from a throat swab | High specificity, varying sensitivity compared with throat culture | CDC clinical guidance; FDA CW240004 |
| Throat culture | Laboratory test | CDC calls it the gold standard diagnostic test | CDC clinical guidance |
| Nucleic acid amplification assay (NAAT) | Molecular detection of S. pyogenes in throat swabs from symptomatic patients | FDA classifies it as product code OYZ, class 1, regulation 866.3740, a separate device type from antigen tests | openFDA device classification, checked 2026-10-30 |
CDC lists RADT and throat culture as the two ways to confirm group A strep pharyngitis in its clinical guidance for health care providers.
How accurate is it, and why negatives may need culture
Two published figures are worth reading side by side, because they measure different things.
| Source | Sensitivity | Specificity | What it measured |
|---|---|---|---|
| Cochrane review (Cohen et al., 2016) | 85.6% (95% CI 83.3 to 87.6) | 95.4% (94.5 to 96.2) | Summary of 105 test evaluations in 58,244 children with pharyngitis, from a review of 98 studies (116 evaluations, 101,121 participants); the review reports poor methodological quality overall and substantial heterogeneity in sensitivity |
| FDA CLIA waiver summary CW240004 | 96.5% (110/114; 95% CI 91.3 to 98.6) | 99.5% (417/419) | One product against blood agar culture in the waiver study |
The Cochrane review notes that in 1,000 children with 30 percent prevalence of group A strep, 43 children with the infection would be missed. It also reports that two antigen test formats, enzyme immunoassay and optical immunoassay, had comparable sensitivity (85.4% versus 86.2%).
For the waived product, FDA states that its sensitivity “warrants the requirement for culture confirmation of negative test results,” and that this is stated in the intended use and labeling.
What to check on a product
- Waived status belongs to the specific device. The example product was previously cleared (K212623) and categorized as moderate complexity; it obtained a CLIA waiver through a separate application. Waiver status applies to the exact product, not to the test type. See CLIA-waived point-of-care testing, CLIA-waived test and CLIA certification.
- The labeling states whether negative results require culture confirmation, as the FDA summary records for the example product.
- The labeling lists the controls that are supplied.
Clinics assembling a point-of-care area can find related supplies under diagnostic, monitoring and imaging supplies. For the wider context, see point-of-care testing and the point-of-care diagnostic station.
Handling basics
- Manufacturer instructions for use are specific to each product; the reagents and kit parts differ between products.
- The control line must appear. A strip with no control line is invalid.
- Positive and negative controls are supplied with the example kit.
- Used swabs, tubes and strips are clinical specimens handled under a facility’s own procedures.
Common misunderstandings
- Ignoring an invalid result. No control line means no valid result.
- Treating a negative as final for every product. The example product’s labeling requires culture confirmation of negatives, and CDC describes RADT sensitivity as varying compared with throat culture.
- Assuming waiver applies to all strep tests. The waiver is device-specific.
FAQ
What is a rapid strep test?
A point-of-care test that detects group A Streptococcus antigen in a throat swab and returns a qualitative result in minutes.
How accurate is a rapid strep test?
The Cochrane review reports summary sensitivity of 85.6% and specificity of 95.4% against throat culture in children; one FDA waiver study of a single product reported 96.5% and 99.5%.
Is a throat culture still used?
Yes. CDC calls throat culture the gold standard diagnostic test and lists it with RADT as the two ways to confirm group A strep pharyngitis.
Does the test need an instrument?
The example lateral flow product has no instrument or electrical components. Molecular (NAAT) tests are a different device type.
Sources
- CDC, Clinical Guidance for Group A Streptococcal Pharyngitis, page dated Nov. 18, 2025; checked 2026-10-30.
- FDA, CLIA Waiver by Application Decision Summary CW240004 (Healgen Rapid Strep A Antigen Test); checked 2026-10-30.
- Cohen JF et al., Rapid antigen detection test for group A streptococcus in children with pharyngitis, Cochrane Database of Systematic Reviews, 2016 (PubMed 27374000); checked 2026-10-30.
- FDA, openFDA device classification, product code OYZ, regulation 866.3740; checked 2026-10-30.
