COVID-19 Antibody Testing —
detect past infection & immunity
COVID-19 antibody (serology) testing at Instant Urgent Care detects past infection and immune response. Blood test with results in 1–2 hours. Available at our Santa Clara, Sunnyvale, and San Jose clinics. Telemedicine pre-screening may be required.
- Detects antibodies from past COVID-19 infection
- Blood sample — results in 1–2 hours
- Useful for immunity assessment
- Telemedicine pre-screening available
- All 3 Silicon Valley locations
- Most insurance accepted
COVID-19 Antibody Test vs Swab Test — what’s the difference?
- Uses a blood sample (finger prick or venous draw)
- Detects antibodies from a past infection or vaccination
- Shows if your immune system previously responded to COVID
- Does NOT detect active/current infection
- Useful for: past infection confirmation, immunity assessment
- Telemedicine pre-screening may be required
- Uses a nasal swab sample
- Detects the virus itself (antigen or genetic material)
- Shows if you have an active current infection
- Antigen: results ~15 min · RT-PCR: results 30 min–2 hrs
- Useful for: symptoms, travel, return-to-work, exposure
- Walk-in, no pre-screening needed
From pre-screening to antibody results
Is COVID-19 antibody testing right for you?
- Had COVID symptoms weeks ago but never tested
- Confirmed past infection — verifying antibody development
- Asymptomatic, possible exposure — want to know past infection status
- Donating plasma — need to confirm COVID-19 antibodies
- Research or occupational health screening
- Currently symptomatic (fever, cough, sore throat)
- Recent close contact with confirmed COVID case
- Travel clearance requirement
- Return-to-work or school clearance needed
- Need to know if you are actively contagious
COVID-19 antibody testing — frequently asked questions
COVID-19 antibody testing (serology testing) detects antibodies in the blood that your immune system produced after a previous COVID-19 infection or vaccination. It does NOT detect an active infection — it shows past exposure. Results help determine whether you may have immunity.
A swab test (antigen or RT-PCR) detects an active COVID-19 infection from nasal secretions — it tells you if you have the virus right now. An antibody test uses a blood sample to detect past infection — it tells you if your immune system has previously responded to the virus.
Consider an antibody test if: you had COVID symptoms weeks ago but never tested, you had a confirmed infection and want to confirm immunity, you are asymptomatic and want to know if you were previously infected, or you need to verify your immune response after vaccination.
COVID-19 antibody test results are typically available within 1–2 hours at our clinic. Results are published to your patient portal with a downloadable PDF.
Not necessarily. While antibodies indicate past exposure, the level of protection varies. Immunity can wane over time, and new variants may partially evade prior immunity. A positive antibody test is not a guarantee against future infection. Consult your provider for guidance.
A telemedicine pre-screening may be required before antibody testing to confirm your symptoms and risk factors. Call us at (408) 791-1210 to determine if a pre-screening is needed for your situation.
Which COVID test should you get?
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Book your COVID-19 antibody test —
results in 1–2 hours.
COVID-19 antibody testing at Santa Clara, Sunnyvale & San Jose. Detects past infection. Results in 1–2 hours. Call (408) 791-1210.
Call during clinic hours