Covid-19: CDC reports issue with reagent used in PCR test sent to states and overseas -- a Q&A

Dr. Daniel Lucey, who has responded to, and monitored information on outbreaks since 2001, has provided a series of updates and analysis on the outbreak, now an epidemic of 2019-nCoV, the novel coronavirus identified in Wuhan China, since Jan. 7. He continues to respond to and break down developments and data on the outbreak here.

Has a technical issue been identified with some of the U.S. Centers for Disease Control and Prevention PCR diagnostic tests that received U.S. Food & Drug Administration emergency use authorization and were sent to 50 States and other nations?

Yes. See this transcript  of the CDC novel coronavirus update telebriefing.

Were any patient specimens either false positives or false negatives?

No. Importantly and fortunately, the problem was quickly identified in laboratories in some states in the standard quality control testing phase BEFORE any patient specimens were tested.

How did CDC explain the problem whereby some states found “inconclusive results?”

CDC stated: “When a state gets the test kits, they have to verify that it works the same in their lab that it worked at CDC. And when some states were doing this, we received feedback that they weren’t — that it wasn’t working as expected, specifically some public health labs at states were getting inconclusive results and what that means is that test results were not coming back as false positive or false negatives, but they were being read as inconclusive.  Now, these were not tests being run on actual clinical specimens from potential patients.

Did there appear to be a problem with one reagent used in the PCR assay?

Yes. As CDC explained: “These were part of the verification process, and because of that we are — when we evaluated what the issue is, we think that there might be an issue with one of the three assays and we think that maybe one of the reagents wasn’t performing consistently, so it’s a long story to say that we think that the issue at the states can be explained by one reagent that isn’t performing as it should consistently and that’s why we are re-manufacturing that reagent, obviously a state wouldn’t want to be doing this test and using it to make clinical decisions if it isn’t working as well as perfectly at the state as it is at CDC, so this is part of a normal process and procedure and redoing the manufacturing is the next step”.

Where does PCR testing for Covid-19 stand in the United States as of Feb. 12?

CDC stated Feb. 12: “Of course, I hoped that this week every state — and every state did receive a kit — every state would be up and running.  How long is it going to take?  I can’t tell you that for sure because I understand that not every state has completed their verification yet.  And it won’t be until we have results from every state that we know which states can continue and which states we need to — we need to get new reagents to.  We’re working closely with FDA.  Again, we do expect this week that some states may move forward.  Other states may need to get additional reagents from CDC, and I don’t have an estimate yet from our laboratory staff as to how long that takes, and when we do, we will definitely be, first, letting the states know and then letting you all know.”

How long does CDC estimate before an antibody test is available to diagnose past infection?

CDC stated: “We have the beginnings of the serological tests, because we now have patients in the United States, we’re able to collect additional specimens but we have to collect them over time so that we can have the appropriate timing of specimens to make sure that we understand what the immune response looks like.  Once we complete the gathering of those specimens from the patients we’ll be able to pretty rapidly, I would say within a couple of weeks, three weeks, four weeks, be able to have a test available but right now, we’re still in the range of testing of gathering the appropriate specimens from the patients in the U.S.”