School programs
Testing for education and training programs with documented requirements.
Testing and documentation
TB testing for school, work and placement requirements.
Plan each visit for one-step or two-step tuberculin skin testing and receive the documentation your organization requests.
Timed testing and documentation
A small test with strict timing
A tuberculin skin test requires both administration and an in-person reading 48 to 72 hours later. Two-step testing adds a second administration and reading, so planning every visit before starting is essential.
One-step testing
Test placement, professional reading and documentation for eligible patients.
Two-step scheduling
Coordinate the additional test and reading within the required intervals.
Form completion
Record results on school, work or placement documents when available.
Testing requirements
TB screening for school, work and placements
Confirm exactly what your organization requests before starting, because a skin test, blood test and two-step baseline are not interchangeable.
Healthcare placements
Baseline testing for eligible clinical students, staff and volunteers.
Employment screening
One-step or two-step testing requested by an employer.
Volunteer positions
Documentation for roles requiring evidence of TB screening.
One-step TST
One administration visit followed by a reading 48 to 72 hours later.
Two-step TST
A second test, usually one to four weeks after a negative first test, plus another reading.
Previous BCG vaccine
Review vaccination and risk history; BCG does not automatically prevent testing.
Prior positive result
Discuss existing documentation and the correct alternative evaluation—do not simply repeat the test.
What to expect
A straightforward visit from arrival to next steps
Know what happens before you arrive, while you are with the clinician and after your assessment.
1
Confirm the requirement
Ask whether you need one-step, two-step, blood testing or specific documentation.
2
Place the skin test
A small amount of non-infectious test material is injected into the forearm skin.
3
Return for reading
A trained professional measures induration between 48 and 72 hours.
4
Complete documentation
Receive the recorded result or plan the second step and any required follow-up.
Prepare for your visit
Bring the essentials
A little preparation helps the clinician understand your health and make safer decisions.
- Photo identification and Ontario health card, if applicable
- All school, employer or placement forms and instructions
- Previous TB skin-test or blood-test records
- BCG vaccination and other immunization information
- History of TB exposure, treatment, positive tests or chest imaging
What a TB skin test can and cannot show
The tuberculin skin test looks for an immune response that may indicate infection with tuberculosis bacteria. It does not contain live bacteria and cannot cause TB. It also cannot, by itself, determine whether a person has latent infection or active, contagious disease.
A small amount of purified protein derivative is placed just under the skin of the inner forearm. A trained professional reads the site 48 to 72 hours later by feeling for firm swelling and measuring it in millimetres. Redness is not the measurement.
One-step and two-step testing
A one-step test has two visits: administration and reading. A two-step baseline has four visits. If the first test is negative, the second is generally placed one to four weeks later, followed by another reading 48 to 72 hours afterward.
Two-step testing helps identify a boosted immune response that might otherwise be mistaken for a new conversion during future testing. Follow the exact requirement supplied by your school, employer or placement rather than assuming which test is needed.
Important history before testing
Tell the clinician about previous positive results, TB treatment, recent exposure, BCG vaccination, immune suppression, pregnancy and recent or planned vaccines. Prior BCG vaccination does not automatically exclude skin testing, but it is part of interpretation.
People with a documented previous positive test or severe past reaction generally should not simply be retested. Bring records so the clinician can determine whether symptom review, a chest X-ray, blood testing or referral is more appropriate.
After the test is placed
Leave the site uncovered unless instructed otherwise. You can usually bathe, but do not scratch, scrub or apply creams and adhesive bandages. Return at the scheduled time even if nothing is visible.
A positive result is not a diagnosis of active TB. Further assessment may include symptoms, risk factors, chest imaging and other tests. Latent TB does not cause symptoms and is not contagious, but treatment may be recommended to reduce future risk.
When symptoms need prompt assessment
A prolonged cough, coughing blood, unexplained weight loss, fever, night sweats or known close exposure should be discussed promptly rather than treated only as an employment-form requirement. Follow public-health or specialist instructions if you are already under investigation.
See the Canadian Tuberculosis Standards for detailed national guidance.
Medical information is for general education and does not replace professional advice. Test choice and interpretation depend on risk, history and the requesting organization’s requirements.
Before you visit
Frequently asked questions
Quick answers about accessing walk-in care at our Scarborough clinic.
When must the test be read?
The reading must be performed by a trained healthcare professional 48 to 72 hours after administration. If you miss that window, the result may not be valid and the test may need to be repeated.
Can I read the result myself?
No. Redness alone is not the measurement. A trained professional feels and measures firm swelling called induration and documents the size in millimetres. Self-reading is inaccurate.
What is a two-step TB test?
After a first negative test is read, a second test is generally placed one to four weeks later and is also read at 48 to 72 hours. It establishes a more reliable baseline for people who may undergo future periodic testing.
Can the skin test give me tuberculosis?
No. The material used in the tuberculin skin test is non-infectious and cannot cause TB. A local raised reaction can occur if the immune system recognizes the test material.
What if I previously had a positive TB test?
Do not book a routine repeat test without clinical review. Bring documentation. A positive test may require symptom assessment, chest imaging or other evaluation to distinguish latent infection from active disease.