Infected? Or Infectious? The HUGE Difference!

By Shlomo Maital

There is a basic problem with COVID-19 testing. And it’s NOT the number of tests alone. It’s the kind of test. It rests on a simple distinction between ‘infectious’ and ‘infected’.

   Current tests that are FDA approved use PCR – polymerase chain reaction [ a method to rapidly make millions to billions of copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail. For COVID-19 tests, PCR multiples the RNA comprising the virus, if there is any, so it can be detected by a rather complex machine and its operator.] The PCR tests test for the presence of coronavirus and the results often take a long time to produce. THESE TESTS ONLY DETERMINE IF THE PERSON IS INFECTED. But they may notv be INFECTIOUS. Why? Because the viral load in their bodies may be so small, that they are really not likely to spread it. PCR tests cannot tell the difference between infectious and infected.

     New tests are on the way. They CAN test if the person has such a high load of virus, that he or she is INFECTIOUS.   These tests, developed among others by epidemiologists at Yale University, can be done at home, using a saliva test not unlike a pregnancy test. They do measure viral load, and signal whether the person is infectious.

     This is what we need. A cheap $1 test, done at home, mass produced, done daily, so each of us can tell whether we have the virus AND ARE LIKELY TO SPREAD IT TO OTHERS IF WE LEAVE OUR HOME OR POSSIBLY EVEN INFECT OTHERS AT HOME.   These tests need to be done daily.

     This distinction was explained on an excellent podcast, Ira Flatow’s Science Friday.

       Why haven’t we gotten such tests sooner? Money. These tests are developed mainly by startups and small labs. They lack the resources to accelerate development and then scale them up. And governments, like the US government, have put billions into vaccines…Operation Warp Speed – and virtually nothing into developing the kind of tests that are needed. The US Admiral who heads Operation Warp Speed keeps telling the media that “we are doing everything possible” – but he is not, and the government is not.

   Infectious? Or just Infected. Help spread the word that the difference is hugely important!

p.s. CIDD is the Center for Infectious Disease Dynamics, at Penn State Univ.