Influenza Specimen Collection

Nasopharyngeal Swab

Materials • Sterile Dacron/nylon swab

• Viral transport media tube 

(should contain 1-3 ML of sterile 

viral transport medium)

Procedure 1 Tilt patient’s head back 70 degrees.

2 Insert swab into nostril. (Swab should 

reach depth equal to distance from 

nostrils to outer opening of the ear.) 

Leave swab in place for several 

seconds to absorb secretions.

3 Slowly remove swab while rotating it. 

(Swab both nostrils with same swab.)

4 Place tip of swab into sterile viral 

transport media tube and snap/cut off 

the applicator stick.

Nasopharyngeal/Nasal Aspirate

• Sterile suction catheter/suction 

apparatus

• Viral transport media tube 

(should contain 1-3 ML of sterile 

viral transport medium)

1 Attach catheter to suction apparatus.

2 Tilt patient’s head back 70 degrees.

3 Insert catheter into nostril. (Catheter 

should reach depth equal to distance 

from nostrils to outer opening of ear.)

4 Begin gentle suction. Remove catheter 

while rotating it gently.

5 Place specimen in sterile viral 

transport media tube.

Note: NP aspirate may not be possible 

to conduct in infants

Nasopharyngeal/Nasal Wash

• Sterile suction catheter/suction 

apparatus

• Sterile normal saline

1 Attach catheter to suction apparatus.

2 Tilt patient’s head back 70 degrees.

3 Insert several drops of sterile normal 

saline into each nostril.

4 Insert catheter into nostril. (Catheter 

should reach depth equal to distance 

from nostrils to outer opening of ear.)

5 Begin gentle suction. Remove catheter 

while rotating it gently.

6 Place specimen in sterile viral 

transport media tube.

Note: NP aspirate may not be possible 

to conduct in infants

Deep Nasal Swab

• Sterile polyester swab (aluminum 

or plastic shaft preferred)

• Viral transport media tube 

(should contain 1-3 ML of sterile 

viral transport medium)

1 Tilt patient’s head back 70 degrees.

2 While gently rotating the swab, insert 

swab less than one inch into nostril 

(until resistance is met at turbinates).

3 Rotate the swab several times against 

nasal wall and repeat in other nostril 

using the same swab.

4 Place tip of the swab into sterile sterile 

viral transport media tube and cut off 

the applicator stick.

Combined Nasal & Throat Swab

• 2 dry sterile polyester swabs 

(aluminum or plastic shafts preferred)

• Viral transport media tube 

(should contain 1-3 ML of sterile 

viral transport medium)

1 Tilt patient’s head back 70 degrees.

2 While gently rotating the swab, insert 

swab less than one inch into nostril 

(until resistance is met at turbinates).

3 Rotate the swab several times against 

nasal wall and repeat in other nostril 

using the same swab.

4 Place tip of the swab into sterile viral 

transport media tube and cut off the 

applicator stick.

5 For throat swab, take a second dry 

polyester swab, insert into mouth, 

and swab the posterior pharynx and 

tonsillar areas. (Avoid the tongue.)

6 Place tip of swab into the same tube 

and cut off the applicator tip.

Packing:

• Label the specimen on viral transport media tube and ensure cap on tube is tightly sealed. 

(Do not use a pencil or pen for labeling, as they can rub off or smear. Instead, use a bar code 

or permanent marker).

• Fill out paperwork in accordance with state health department guidelines.

• Include a frozen cold pack with the specimen(s).

• Pack specimens in accordance with U.S. Department of Transportation regulations regarding 

shipment of biological substances, see www.cdc.gov/flu/professionals/diagnosis/index.htm.

Storing:

• Specimens should be placed into sterile viral transport media and immediately placed on 

refrigerant gel packs or at 4 degrees Celsius (refrigerator) for transport to the state public 

health laboratory.

• Keep specimens refrigerated (2-8 degrees Celsius, 26-46 degrees Fahrenheit) prior to shipping.

Shipping:

• Ship specimens for testing as soon as possible.

• If delivery will be delayed for more than 3-4 days, specimen should be frozen at -70 degrees Celsius (-94 

degrees Fahrenheit).

• Ensure specimen will be received by the public health laboratory during normal business hours.

Considerations: 

• A nasopharyngeal (NP) swab is the optimal upper respiratory tract specimen collection method for influenza 

testing. However, such specimens cannot be collected from infants and many older patients may not allow 

an NP specimen to be collected. Alternatively, a combined nasal and throat swab specimen or aspirate 

specimens can provide good influenza virus yield.

• Some influenza tests are approved only for use with certain kinds of respiratory tract specimens, so follow 

guidelines provided by test. Also, some tests (e.g., rapid influenza diagnostic tests) are only approved for 

certain kinds of respiratory tract specimens. 

• For best results (i.e., highest influenza virus yield), collect respiratory tract specimens within four days of 

illness onset. 

• Most sensitive and accurate tests for influenza virus detection are molecular or nucleic acid amplification 

tests (RT-PCR).

• Negative test results obtained from rapid influenza diagnostic tests (RIDTs) that detect influenza viral 

antigens do not exclude influenza virus infection in patients with signs and symptoms of influenza. A 

negative test result could be a false negative and should not preclude further diagnostic testing (such as 

RT-PCR) and starting empiric antiviral treatment.

• A surgical mask and gloves are recommended at a minimum for all procedures. For some patients 

and procedures, additional precautions may be indicated, see Standard Precautions at www.cdc.gov/

hicpac/2007IP/2007ip_part4.html#a4.

CS246972