Welcome to the State of California 

CDPH Viral and Rickettsial Disease Laboratory 

The CDPH Viral and Rickettsial Disease Laboratory (VRDL) serves as a statewide reference laboratory offering diagnostic testing for influenza and a broad array of other respiratory pathogens. VRDL routinely performs diagnostic testing in a variety of situations, including institutional or community respiratory outbreaks, individual cases of severe respiratory illness, and outpatient cases of influenza-like illness submitted by Centers for Disease Control and Prevention (CDC) Influenza Sentinel Providers. The VRDL testing capabilities include viral culture, polymerase chain reaction (PCR), serologic testing, sub-typing, strain characterization and antiviral resistance testing. 

In the current novel influenza A H1N1(swine flu) epidemic, the VRDL serves as the state reference laboratory by providing PCR testing for influenza, confirmatory testing for novel influenza A H1N1(swine flu), and guidance and assistance to our local public health laboratory partners. Antiviral resistance testing will be performed on a subset of specimens tested to monitor for changing resistance patterns. VRDL is also working on development of new techniques and assays (e.g., neutralization assays to test for immunity) in order to enhance our repertoire of diagnostic testing that may be available in the current novel influenza A H1N1(swine flu) epidemic.

Diagnostic Testing for Influenza 2009 A/H1N1

Diagnostic testing is recommended on suspect cases of novel influenza A H1N1(swine flu). Active infection with swine influenza can only be confirmed by polymerase chain reaction (PCR) assays, including sub-typing and further characterization by other special PCR assays. PCR and sub-typing is available at certain local public health laboratories in California and the CDPH Viral & Rickettsial Disease Laboratory (VRDL).  Confirmatory testing with PCR specific for novel influenza A H1N1(swine flu) is also available at VRDL and the CDC.   Specimens should be submitted through the local public health department or laboratory and testing will be prioritized based on guidance issued in the latest CDPH Health Alert [see the CDPH Novel Influenza A H1N1(Swine Flu)- Information for Health Professionals Webpage]

Commercial rapid influenza antigen testing in the evaluation of suspected swine influenza cases should be interpreted with caution.  The sensitivity and specificity of rapid antigen testing for identifying swine influenza is unknown.  A negative result does not exclude a diagnosis of swine influenza A.  A positive result may be helpful, but does not distinguish between seasonal and swine influenza viruses.  Therefore, if a patient tests negative for influenza by rapid antigen testing, specimens should be sent for further characterization (including PCR and sub-typing) to the local public health laboratories or VRDL.   More information on the utility of rapid antigen testing for swine influenza is available at the CDC's:Use of Rapid Influenza Diagnostic Tests for Patients with Influenza -like Illness during the Novel H1N1 Influenza Virus (Swine Flu) Outbreak information page.

Diagnostic work on clinical samples from patients who are suspected cases of swine influenza (e.g., rapid antigen testing or PCR) can be performed under BSL-2 conditions.  All other sample manipulations should be done inside a bio-safety cabinet. (BSC).  Viral isolation on clinical specimens from patients who are suspected cases of swine influenza A (H1N1) virus infection should be performed in a BSL2 laboratory with BSL3 practices (enhanced BSL2 conditions).  Additional precautions include:

  • Recommended Personal Protective Equipment (based on site specific risk assessment)
  • Respiratory protection  - fit tested N95 respirator or higher level of protection
  • Shoe Covers
  • Closed-front gown
  • Double gloves
  • Eye protection (goggles or face shields)


  • All waste disposal procedures should be followed as outlined in your facility standard laboratory operating procedures

Appropriate disinfectants


  • 70 % Ethanol
  • 5 % Lysol
  • 10 % bleach

More information on bio-safety recommendations can be found on the CDC's H1N1 Influenza Virus Bio-safety Guidelines for Laboratory Workers information webpage.


 Infection Control Precautions During Specimen Collection

For collecting respiratory specimens from an ill confirmed or suspected swine influenza case, the following is recommended:

  1. Personnel collecting clinical specimens should wear a fit-tested N95 respirator, goggles, disposable gown, and disposable gloves.  [Bronchoalveolar lavage specimens should be collected in a negative-pressure room using a Powered Air Purifying Respirators (PAPR)].

  2. When completed, place all personal protective equipment in a biohazard bag for appropriate disposal.

  3. Wash hands thoroughly with soap and water or alcohol-based hand gel

More information on bio-safety recommendations can be found on the CDC's Interim Guidance on Specimen Collection, Processing, and Testing for Patients with Suspected Swine-Origin Influenza A (H1N1) Virus Infection information webpage.


Minimum Specimen Requirements

Respiratory Specimens
  • At a minimum, collect a nasopharyngeal swab (nasopharyngeal wash or nasopharyngeal aspirate are also acceptable).  Orophayrngeal (throat) swabs are acceptable, but may not have as high yield.  If oropharyngeal specimens are collected, they should be accompanied by a specimen from the nasopharynx. Place the swabs in a standard container with 2-3 ml of viral transport media (VTM).
  • If the patient is hospitalized with pneumonia, specimens from the lower respiratory tract (e.g., tracheal aspirate, bronchoalveolar lavage) should also be obtained.
  • Use dacron-tipped swabs only. Cotton or calcium alginate swabs are not acceptable for PCR testing
  • For cases or contacts of cases with confirmed swine influenza, collect as much blood as possible (recommended volumes 3- 10 cc from children and 10-20 cc from adults) in a serum separator tube (red top or tiger top).  If possible, spin to separate sera before packaging.

Specimen Storage and Shipment

Specimens should be collected within the first 24-72 hours of onset of symptoms and no later than 5 days after onset of symptoms.  The specimens should be kept refrigerated at 4ºC and sent on cold packs if they can be received by the laboratory within five days of the date collected. If samples cannot be received by the laboratory within five days, they should be frozen at -70 ºC or below and shipped on dry ice.

After review with the local health department, any requests for diagnostic testing at VRDL must be accompanied by the Influenza and Respiratory- Individual Specimen Submittal Form*.

The form must be filled out as completely as possible or the specimen will not be tested.
Specimens should be shipped per usual protocol to either your local public health laboratory or:

California Department of Public Health / VRDL  
Specimen Receiving /Swine Influenza Surveillance
850 Marina Bay Parkway   
Richmond, CA 94804     
(510) 307-8585
(510) 307-8578 (fax)

*If the sample cannot be subtyped, please alert  VRDL by calling (510) 307-8585  and provide the ETA and Tracking # for the shipment.




Last modified on: 11/1/2011 2:20 PM