May 31, 2020
Whatcom County Health Department Communicable Disease & Epidemiology Division
Update on COVID-19 Reporting and Testing
- Report all cases with positive COVID-19 PCR, NAAT POC, or antibody test results immediately to WCHD (fax 360-778-6103, confidential voicemail 360-778-6150).
- Instruct patients with symptoms of COVID-19 or positive PCR test results to self-isolate pending test results or interview with WCHD Case Investigator.
- Be aware of the limited clinical utility of COVID-19 antibody testing and of the Large-Scale Geographic Seroprevalence Surveys that CDC is doing in conjunction with WA DOH and commercial laboratories.
Reporting cases of COVID-19:
Report all cases of COVID-19 to Whatcom County Health Department (WCHD). All COVID-19 testing (including PCR and antibody tests) are reported by laboratories to DOH, but this information is incomplete and clinicians are still required to report all cases to local public health.
Timely reporting is necessary for timely case investigation and contact tracing, so that effective isolation and quarantine can be implemented to reduce the spread of COVID-19. WCHD is staffed 7-days per week for COVID-19 response. Please use the attached Positive COVID-19 Report Form to notify WCHD of all patients with positive SARS-CoV-2 rRTPCR or antibody test results. Although DOH notes that COVID-19 cases should be reported immediately, WCHD prefers that COVID-19 case reports are faxed (360-778-6103) or phoned in to voicemail on our 24-hour Communicable Disease Report Line (360-778-6150).
Instruct patients with symptoms consistent with COVID-19 to self-isolate at home while tests are pending, and if your patient has been at high risk of exposure (close contact to a confirmed case or potential exposure in an outbreak setting), consider the possibility of an initial false negative test result, especially if tested soon after onset of symptoms, and do not discontinue isolation. The DOH patient handout, What to do if you have confirmed or suspected coronavirus disease (COVID-19), provides information and instructions.
Nucleic Acid Amplification and Serology
PCR and NAAT nucleic acid amplification tests are very specific for COVID-19. The rRT-PCR is more sensitive than t he Abbott ID NOW COVID-19 POC test, which is associated with high false negative rates when viral loads are low (i.e. high Ct on PCR). Patients with positive results for either method are classified as confirmed cases, whether symptomatic or not. Detection of SARS-CoV-2 RNA can persist for over a month, but infectiousness is unlikely more than 10 days after onset of symptoms, except with severely immunocompromised patients. See the WA DOH Interim COVID-19 Testing Guidance for Healthcare Providers for updated public health recommendations and priorities for COVID-19 PCR testing. At this time, all patients with symptoms consistent with COVID-19 should be tested, and testing of asymptomatic patients limited to:
- Close contacts of a case (if a close contact tests negative, these individuals still need to remain in quarantine for 14 days after their last date of exposure)
- Individuals exposed to COVID-19 during an outbreak in a congregate setting (e.g., long term care facility, shelters, correctional settings, agricultural workers, meat-packing plants, etc.)
- Persons from racial and ethnic minority groups disproportionately affected by adverse COVID-19 outcomescurrently African Americans, Hispanics and Latinos, American Indians and Alaska Natives
Testing asymptomatic people can be considered for:
- Persons who are pregnant and present in labor
- People undergoing procedures that increase the risk of aerosolized particle spread
- People undergoing invasive surgical procedures (if possible, test within 48 hours of procedure)
Antibody tests were developed and marketed initially without independent validation, so there was a wide range of sensitivity and specificity for antibody to SARS-CoV-2. Although there are now antibody tests available that have been validated, and accurately indicate an immune response to infection with the COVID-19 virus, correlation with immunity has not been established. Other than helping to determine whether or not a person has previously been infected with the virus, other clinical decisions cannot be made with the results, other than selection for plasma donation for COVID-19 plasma therapy. “Antibodies most commonly become detectable 1-3 weeks after symptom onset, at which time evidence suggests that infectiousness likely is greatly decreased and that some degree of immunity from future infection has developed. However, additional data are needed before modifying public health recommendations based on serologic test results, including decisions on discontinuing physical distancing and using personal protective equipment.” Patients with positive antibody tests and history of clinical illness consistent with COVID-19 since January 2020, or close contact to a lab confirmed case or exposure to an outbreak setting, are classified as probable cases of COVID-19. Patients who have symptoms consistent with COVID-19 and close contact to a lab-confirmed case or exposure to an outbreak setting within the 14-day incubation period, but have no positive PCR results, are considered probable cases. Recently (symptom onset within past 10 days) or currently ill cases should be isolated. Probable cases are interviewed by a WCHD Case Investigator to determine whether they are linked to other cases or outbreaks, determination of duration of isolation, and referral for support services during isolation, if needed.
Although antibody testing is of limited clinical value currently, it is a powerful tool for COVID-19 surveillance in regional epidemiology. CDC and Washington State are working with large commercial labs on Large-Scale Geographic Prevalence Surveys. This project will provide key information on the prevalence of recent and past COVID-19 infection over time that will help direct our clinical and population COVID-19 control guidelines.
Large-scale Geographic Seroprevalence Surveys https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/geographic-seroprevalence-surveys.html
Interim Guidelines for COVID-19 Antibody Testing https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html
Guidance for Certifying Deaths Due to Coronavirus Disease 2019 (COVID–19) https://www.cdc.gov/nchs/data/nvss/vsrg/vsrg03-508.pdf
What to do if you have confirmed or suspected coronavirus disease (COVID-19) https://www.doh.wa.gov/Portals/1/Documents/1600/coronavirus/COVIDcasepositive.pdf
WCHD Drive-Through COVID-19 Testing Referral Instructions https://www.whatcomcounty.us/DocumentCenter/View/46883/WCHD-Drive-Through-COVID-19-Testing-Referral-Instructions_Form41220
FDA announced that SARS-CoV-2 antibody tests that have not submitted test validation data to FDA and do not have an EUA pending will be removed from their ‘Notification Llist” of available antibody tests. Those who submit an EUA request have to provide the FDA with validation data within 10 days of the submission. (5/18/20) https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-provides-promised-transparency-antibodytests
WA DOH COVID-19 Infection Guideline (last update 5/18/20) https://www.doh.wa.gov/Portals/1/Documents/5100/420-107-Guideline-COVID-19.pdf
Interim COVID-19 Testing Guidance for Healthcare Providers (updated 5/27/20) https://www.doh.wa.gov/Portals/1/Documents/1600/coronavirus/Interim-2019NovelCoronavirusQuicksheetProviders.pdf