Now 12 weeks after the first case on United States soil of COVID-19 on Jan. 21, 2020, access to testing remains a challenge. South Korea and the United States reported their first cases on the same day; 6 weeks later, testing in South Korea was . The result has been two-fold: individuals with COVID-19 are unknowingly transmitting infection to others and public health efforts at mitigation have been hampered by lack of reliable data.
Up until now testing for COVID-19 in the U.S. has largely relied on PCR assays of nasal swab collections by healthcare professionals. Scale-up efforts have been hampered by lack of testing capacity, as well as a shortage of nasal swab test kits. There is now a second option for testing: an antibody-based serology test that can be done with a pinprick blood test with results available at the point-of-care in 10-15 minutes. The antibody test can be used as a diagnostic for active infection (IgM antibodies), similar to a PCR test, and in addition, for assessing immunity from prior infection (IgG antibodies). This means antibody tests could be used to survey a population to determine cumulative infection and to allow certain individuals to return to work and partially lift stay-at-home orders.
we described a self-service delivery model based on PCR tests in which patients would perform a self-swab at home under a provider's discretion and then receive results in 1-2 days. However, since then, on March 20, the FDA issued that at-home self-swab is not authorized. Here we redouble our policy recommendations on home-based testing and extend it to include at-home antibody testing.
At-Home Antibody Testing
COVID-19 serologic antibody testing assesses for IgM and IgG antibodies from COVID-19. The procedure is similar to a fingerstick blood glucose test. At-home antibody testing would enable a testing pathway for COVID-19 to be delivered remotely:
-
Step 1: Individuals with symptoms or exposure to COVID-19, or who want to test for immunity, would access a telemedicine service and be seen by a qualified clinician who would assess them and determine whether testing is appropriate.
-
Step 2: A test kit would be sent via mail or picked up at a local pharmacy or lab. Individuals would then prick their finger as for a blood glucose test. Results appear in 10-15 minutes, similar to a home pregnancy test with colorimetric reading.
-
Step 3: The test kit results would be uploaded to a mobile app or be viewed over a video telemedicine consultation to interpret the results and provide counseling on next steps.
Recently a private U.S. company commercial efforts towards launching an at-home antibody testing service similar to what is described above. However, they currently do not have FDA approval.
Benefits
For individuals with symptoms of COVID-19 or concern for exposure, at-home testing offers wider availability with lower costs and mitigated risk of exposure to the virus. Because antibodies form over the first several days of the infection, testing is more appropriate for ruling in a diagnosis of COVID-19 than it is for ruling it out -- that is, a negative test result does not by itself indicate that the patient is not infected.
For individuals seeking testing for immunity, at-home testing provides convenience and lower cost. This may be particularly important for healthcare workers and other essential workers for whom immunity may have implications in terms of the ability to be at work and the type of work they can safely perform.
At-home testing also has efficiency and equity considerations. Decreased use of healthcare facilities during an epidemic has the advantage of allowing for scarce resources to be allocated appropriately. Lowering the friction of access to testing could also decrease any language, cultural, or logistical barriers to seeking care at a clinic, emergency room, or hospital.
Evidence Base
To the best of our knowledge, at-home antibody testing for COVID-19 has not been studied. However, fingerstick blood tests for conditions like diabetes and colorimeter tests such as pregnancy tests are commonplace. Moreover, unlike nasal swab PCR testing, which requires patients to push a swab deep into their nostril to get a reliable sample, the performance of fingerstick blood tests are less likely to be operator dependent and have fewer false negatives due to user error.
In a recent in Nature, a study that compared antibody testing in a healthcare setting with PCR found a sensitivity of 70% in the early stage of the infection (days 4-10) and 92% in days 11-24; specificity was reported to be 100%.
Policy Considerations
On March 16, the FDA provided on a pathway for commercial manufacturers of antibody tests that does not require an Emergency Use Authorization application and can rely on validation data from other countries. However, the guidance specifically precludes home use. There are reasons for that, including quality control, which is obviously of highest priority; but as more robust testing is conducted, we want to emphasize the strengths of home-based testing.
We recommend that regulators accelerate access to home-based testing. Specifically:
-
The FDA should create a pathway for high-quality at-home antibody testing, ideally by updating the March 16 guidance to also pertain to at-home testing.
-
The FDA should create guidance on physician-directed at-home testing services, ideally not by requiring validation data but instead reviewing the process for assessment, instructions, and test interpretation and reporting. Alternatively, the FDA should allow at-home testing for healthcare professionals immediately and use this cohort for validation data.
-
The CDC should update clinical guidelines on antibody testing for diagnosis and assessing immunity, including prioritizing populations for testing, beginning with healthcare professionals and their families.
-
Federal and state governments should explore mechanisms to improve the supply of antibody testing, including expanding manufacturing in the United States.
-
Home-based self-swab PCR testing should be expediently pursued. Given the lower sensitivity of antibody testing, the ideal diagnostic protocol would include both PCR and antibody test.
-
Transparent, de-identified reporting with gender/racial and ethnic breakdown by county or zip code should also be considered, so that we better understand where testing is occurring and how to consider gaps in care.
The space of biomedical innovation for COVID-19 will be rapid, and the human health and economic benefits of delivering these innovations at scale is urgent. We need policy innovation to keep apace.
Kavita Patel, MD, is an internal medicine physician in Washington, D.C., and a former Director of Policy in the Obama White House and a Senior Staff member to the late Senator Edward Kennedy.
Shantanu Nundy, MD, is a primary care physician and the Chief Medical Officer of Accolade Inc.