US officials in thought of using Pool Testing for Covid-19

United States: The continues rise in the numbers of COVID-19 cases in US made officials to rethink the country's current testing strategy and come up with new methods to determine number of people have been exposed to the virus.

Speaking regarding the issue, Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases said, "The US's current approach of only testing people who display COVID-19 symptoms, isolating them, and tracing their contacts isn't working as some people are asymptomatic and spreading the virus unknowingly and that others are unable to self-quarantine after virus exposure."As a remedy from this current faulty approach, Dr. Fauci said that officials were having serious discussions about a possible shift to "pool testing".

Pool Testing is different from other testing methods

Pool testing is also dependent on the same polymerase chain reaction (PCR) technology as individual diagnostic tests, but the method by which people are tested is quite different than the regular testing approach which was used till date.

Speaking on the issue, infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland said, "The pool testing method combines samples from multiple people in order to carry out one test on the whole batch." He added, "This means if the result is positive, it's impossible to know which individual sample was responsible for it." But if a pool gets a positive result, it can move to a second phase of testing, which breaks down the pool into smaller samples to identify the infected person or people.

public health expert Carol A. Winner, MPH, public health expert and founder of the personal distancing Give Space movement said, "Think of it like the first call of 'everyone in the pool' and 30 jump in and then comes 'adult swim only', and 25 come out. Those remaining five are then tested instead of all 30.

Pool testing process also speeds up the testing process because it consumes less time than getting a sample from an individual and then putting it through all the necessary lab processes. For starters, it can be more cost-effective and protect laboratories from becoming overburdened.

Deborah Birx, MD, coordinator of the White House Coronavirus Task Force said, "Pooling would give us the capacity to go from a half a million tests a day to potentially five million individuals tested per day."

Flaws in pool testing

Speaking about negatives in the test, Dr Adalja says, "Despite pool testing being more cost-effective and less time-consuming it's not a secure approach to test Covid-19. If there are too many infected people in the initial sample, it may be impossible to identify them in the group. "If the prevalence is high, all batches are going to be positive and they will be less useful".

"The samples can also be less viable if the pool is too large, as diluting them with large numbers might make some positive cases show up as negative," says Winner Pool testing can be processed in only some areas of US. It may not be the best approach where record levels of new cases have been reported. Whereas, it might work where cases have been trending downward.

Winner says that containment is our best defense in controlling the spread of COVID-19. He added, "Containing the spread of the virus requires testing for infection, contact tracing for anyone likely to be exposed to those who are infected, and subsequent isolation for all those who are infected."