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CD4 T-Cell Count with Stimulation (Serum Stimulation for COVID-19 Spike Response)

Published: August 9, 2026Updated: August 16, 2026

This test measures your immune system’s response to COVID-19 by assessing how your CD4 cells (a type of white blood cell) react after exposure to the virus spike protein.

Quick summary

["Helps evaluate immune activation in response to COVID-19 infection or vaccination."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
100858-0
Short code
CD4+154/CD4 stim COVID Spike
Synonyms
CD4+154/CD4 stim COVID Spike
Category
coagulation
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is CD4 Stimulation Testing For?

CD4 stimulation testing evaluates how your immune system responds to the spike protein of COVID-19. This helps doctors understand whether your immune cells are activated, which can be important for monitoring immune function during or after infection or vaccination.

How Is This Test Performed?

A small blood sample is drawn, and your CD4 cells are exposed to a spike protein from COVID-19. The test measures how many CD4 cells grow or change in response, indicating immune activation.

Why Might You Need This Test?

This test may be used if you have a weakened immune system, are recovering from COVID-19, or are being monitored for immune response after vaccination. It can help assess how well your body is mounting an immune reaction.

What Does the Result Mean?

Results show whether your CD4 cells are responding to the spike protein, which can indicate immune activation. Higher stimulation suggests a strong immune response, while lower stimulation may suggest a weaker or altered response.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CD4 Stim Test

Frequently asked questions

Why was I asked to take this test?
Your healthcare provider may recommend this test if you have a history of COVID-19, are immunocompromised, or are being evaluated for immune response after vaccination.
How long will it take to get my results?
Results are typically available within 1–3 business days, depending on lab processing times.
Can I eat or drink before this test?
No special preparation is needed. You may eat and drink normally before the blood draw.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy