As of July 5, a total of 35,512,916 COVID-19 tests have been conducted nationwide. Between June 28 and July 5, an average of 638,909 tests were conducted daily.
While testing capacity in the U.S. has increased significantly since March, according to some public health experts, it’s still not enough to control the pandemic. Experts disagree on exactly how many tests should be conducted, with recommendations ranging from 900,000 to 25 million tests per day.
Part of the challenge is that diagnostic testing for COVID-19 is currently done on an individual basis. This requires many resources, including swabs, reagents, and personal protective equipment (PPE) for healthcare workers. It has also led to backlogs at labs where tests are processed. An additional challenge is that the federal government is ending funding for testing sites in some areas, including those where COVID-19 cases are rising.
One possible solution to increase testing capacity is pool testing. The White House Coronavirus Task Force introduced pool testing as a new potential strategy in late June, saying that it has the potential to increase testing capacity to 5 million people per day.
The principle of pool testing, also known as batch testing, is simple. Individuals receive a nasal swab, the standard method for collecting COVID-19 samples. A portion of each individual sample is combined into a single pool, which is then tested in a single diagnostic process. If the results come back negative, all of the individuals in the pool are cleared. If the results come back positive, everyone is tested individually to identify who has COVID-19.
The protocol of pool testing was first established during WWII to test for syphilis, and has been used during outbreaks of other sexually transmitted infections, including HIV.
As of early July, discussions about pool testing are ongoing, but the White House Coronavirus Task Force has not yet announced definitive plans for implementing the strategy.
The Food and Drug Administration has not yet given their approval for any labs or test-makers to use the pool testing method, although the agency issued guidelines for those who want to develop pool-testing protocols. While there is an urgent need to increase testing capacity, care must be taken to ensure that mixing samples won’t hurt accuracy.
There is currently at least one company, PharmaCyte, that is awaiting Emergency Use Authorization (EUA) from the FDA for a pool testing kit. According to a June 29 press release, the biotech company licensed a COVID-19 test that is ideal for pool testing from a Hong Kong-based company. If granted EUA, PharmaCyte’s test may become the first deployable pool testing method in the U.S.
The most significant benefit of pool testing is the impact it will have on increasing testing capacity. Ramping up the number of daily tests would make it easier to screen asymptomatic individuals, who can still be responsible for spreading COVID-19 to others. Experts suspect that anywhere from 25% to 45% of infected individuals are asymptomatic; identifying and isolating these individuals is a key component of slowing the coronavirus’ spread.
Pool testing would also address the issue of limited testing supplies, since only one diagnostic test would be needed per batch. Labs only need to run individual diagnostic tests if a batch returns a positive result. This method of testing could also presumably return results faster, which is critical in isolating those who test positive, and tracing their contacts to slow the spread of infection. Health experts also predict that this strategy could save businesses and schools up to 70% of testing costs.
While pool testing may not work in all settings, experts say that can be useful in group settings, such as schools, summer camps, offices, and correctional facilities, in low-transmission areas. Regular pool testing in these controlled groups could make it easier for people to return to their usual routines and activities.
One of the key downsides of pool testing is that it isn’t very useful in coronavirus hotspots, where there is a higher likelihood that batches will return positive results. Batch testing only has financial and logistical benefits when the majority of tests come back negative. In areas where transmission rates are higher, batch testing may cause more harm, as individuals have to wait for two rounds of results, prolonging the time when they may be unintentionally infecting others.
It is also challenging to find the ideal number of samples to combine into a single batch. If a pool is too large, there is a greater chance that a positive case with a low viral load will be too diluted to trigger a positive result, resulting in a false negative for the entire batch.
Yes, a number of other countries are currently doing pool testing for COVID-19, including China, India, Singapore, and Germany. While the practice was adopted in Wuhan, China, as part of a strategy to rapidly test all of its citizens, in countries like Singapore and India, it was implemented among more targeted groups, including migrant farm workers, and residents of long-term care facilities.
|Centers for Disease Control and Prevention (CDC)||https://www.cdc.gov/coronavirus/2019-ncov/index.html||The CDC is the United States’ leading national public health organization. Its mission is to protect public health and safety through the control and prevention of disease, injury, and disability in the U.S. and abroad.|
|World Health Organization (WHO)||https://www.who.int/||A specialized agency of the United Nations, WHO is responsible for international public health. Headquartered in Geneva, Switzerland, it has field offices worldwide.|
|Association of Public Health Laboratories (APHL)||www.aphl.org||The APHL is a nonprofit organization in the United States that represents laboratories that protect public health and safety.|
|State Departments of Health||https://www.fsis.usda.gov/wps/wcm/connect/fsis-content/internet/main/topics/recalls-and-public-health-alerts/additional-recall-links/state-departments-of-public-health/ct_index||Each state in the U.S. has its own department of health. These public health departments are currently coordinating efforts for COVID-19 testing and treatment.|