Healthcare providers should use personal protective equipment like N95 masks, gloves, and gowns when collecting respiratory specimens from patients suspected to have Covid-19. Nasopharyngeal and oropharyngeal swabs are recommended for diagnostic testing, and sputum samples can also be tested if a patient develops coughing. Specimens should be stored at refrigerated or frozen temperatures and shipped for testing within 72 hours. PCR testing is the gold standard method for detecting the presence of SARS-CoV-2 and diagnosing an active infection, though results can vary in turnaround time. Antigen tests provide faster results but are less sensitive, so negative results may need confirmation with PCR. Antibody tests detect a past infection but cannot

1. Covid-19 Testing

2. Collecting and Handling Specimens Safely
• For healthcare providers collecting specimens or working within 6 feet of patients suspected to be
infected with SARS-CoV-2, use recommended personal protective equipment (PPE), which
includes an N95 (Face Masks) or higher-level respirator, eye protection, gloves, and a gown.
• For diagnostic testing for current SARS-CoV-2 infections, collecting and testing of an upper
respiratory specimen, Nasopharyngeal specimen (NP) collection /Oropharyngeal (OP) (throat)
specimen is recommended.
• Testing lower respiratory tract specimens is also an option. For patients who develop a productive
cough, sputum can be collected and tested for SARS-CoV-2 when available. However, the
induction of sputum is not recommended due to the possibility of aerosol production during the
procedure.

3. Storing and Shipping Respiratory Specimens
• Store respiratory specimens at 2-8°C for up to 72 hours after collection.
• If a delay in testing or shipping is expected, store specimens at -70°C or below.
Store extracted nucleic acid samples at -70°C or lower.

4. PCR: Gold Standard for SARS-CoV-2
Detects presence of SARS-CoV-2 viral nucleic acid, generally during acute phase of
infection.
Result Interpretations:
Positive: Active infection with SARS-CoV-2
Negative: likely not infected when the sample was collected.

5. PCR: Gold Standard for SARS-CoV-2
Limitations
• Sample collection and transport
impact the test accuracy
• Individuals may still test positive by
PCR but not be infectious
• Turnaround time ranges (<1hr to
multiple days).
Benefits
• Most sensitive and specific
• Gold standard to diagnose acute
infections
• Can identify infection in asymptomatic
individuals

6. Antigen tests: Quicker, Cheaper but less sensitive
Detects the presence of SARS-CoV-2 by binding to viral surface proteins (antigens)
.
Results Interpretations:
Positive: Active infection with SARS-CoV-2, person is presumed to be contagious.
Negative: does not rule out infection, may be considered presumptive & confirmed
with a molecular test.

7. Antigen tests: Quicker, Cheaper but less sensitive
Limitations
• No amplification steps: Far less
sensitive (Risk of false negatives).
• Best for symptomatic individuals early
during infection (when viral load is
highest.
• False Positive can occur.
Benefits
• Rapid (~15mins)
• High specificity
• Positive results informs clinical
decisions and infection control
measures.

8. Antibody test: useful to assess exposure, not for
diagnosis
Detects the body’s immune response to SARS-CoV-2 (i.e. past infection,not active
infection)
Takes 2-3 weeks post-infection to develop antibodies (IgM, IgG)
Results Interpretations:
Positive: Previous infection with SARS-CoV-2, Doesnot indicate current infection.
Negative: Probably has not been infected with SARS-CoV-2 or too early in infection
to have detectable antibodies.

9. Antibody test: useful to assess exposure, not for
diagnosis
Limitation
• Risk of false positives
• Should not be used to diagnose active
infection.
• Unknown how long protective
antibodies last (months?)
Benefits
• Determining population-level
exposure, especially when some are
asymptomatic.
• Determine who can donate
plasma/blood as possible treatment for
severely ill.