“Pandemic ?” – A necessary response

I read with plenty of interest Dr. F.E. Dias’ article titled “Pandemic ! Pandemic ?” published in “The Island” of 03.09.2021. It gives a good account of the nature of the Covid virus infection, and defines the terms “epidemic” and “pandemic” so that there is no doubt in the reader’s mind about what he means when he puts a question mark on the word “pandemic”. He seems to expound the theory that what the world is faced with, after all, may not be a pandemic, because many of the cases labelled as Covid positive could well be influenza. I was delighted, for if he is correct, what a good thing it would be for the world, and particularly for the developing countries. We would not have to be locked down and the economy of the world could get back to business benefiting poor people.

However, I decided to do some reference work on this matter and share my findings with The Island readers, as this is a very critical matter for Sri Lanka.

Dr. Dias’ argument seems to be based on the fact that the Centre for Disease Control (CDC) in the US had on the 21st of July 2021 announced the withdrawal of the well known and widely used Reverse Transcription – Polymerase Chain Reaction test, commonly known as the PCR test, and advised the use of multiplexed assays instead, which are capable of picking both the Covid and flu. This CDC alert had made a lot of people, including virologists, to believe that the PCR test cannot distinguish between Covid virus and flu virus. Dr. Dias says a person who has fought off a flu may carry remnants of virus particles and may prove to be positive when tested with a PCR. Dr. Dias would be correct if what he says about the PCR test is correct, that it cannot distinguish Covid from flu.

When the CDC revoked the emergency use authorisation of the PCR test and recommended the use of multiplexed assays, a lot of people thought the PCR test cannot distinguish Covid virus from the flu virus, resulting in all flu cases being added to the account of Covid. The claim that the PCR cannot differentiate Covid and flu was inflated by the social media. Even some molecular biologists had agreed with these ideas, and that had given credence to the view that in fact PCR is unreliable and gives a lot of false positives. Further, soon after President Joe Biden was sworn in, the WHO had issued a circular advising laboratory technologists to carefully follow the instructions of the manufacturers of PCR kits, to be cautious in interpreting results, and to consider the clinical findings also when issuing reports. This was also taken as a stricture on the PCR test by social media, and it added to the evidence against PCR. But the fact of the matter is that the WHO usually issues such circulars with regard to important investigations to ensure that clinicians and lab staff take every care in their work, especially when a worldwide problem is being tackled.

Contrary to what Dr. Dias says the CDC in the US announced the withdrawal of PCR not because it is unreliable, cannot distinguish between Covid and flu, and therefore could give lot of false positives amplifying the magnitude of the pandemic; but because it wanted the health services to use other multiplexed assays which could pick Covid and also flu, as the country was going into the flu season. The demand for PCR declined with the emergence of other multiplexed assays capable of detecting several types of viruses. All this had contributed to the formation of an opinion that the PCR is non-specific to some degree, and its ability to distinguish the Covid virus from flu viruses was questionable.

The veracity of this opinion, which has been made public in Sri Lanka too due to the article written by Dr. Dias is of paramount importance, for the world cannot fight a pandemic using a test that is flawed. Therefore, we have to get to the bottom of this matter. Further the world continues to use the PCR test, whatever may be the state of affairs in the United States. The influenza afflicts the northern hemisphere in the winter months, and these countries would want to be certain about the diagnosis, as both Covid and influenza thrive under cold climates. However, this may not be a reason to jettison the PCR test.

The CDC spokesperson, Jade Fulce, after explaining why the emergency use authorisation of the PCR test was revoked, says that the PCR could still be considered the gold standard for detecting the SARSCov-2 virus. The CDC alert doesn’t mean that the PCR test cannot differentiate between Covid and flu. Further, Kelly Wroblewsky, the Director Infectious Disease Programmes at the Association of Public Health Laboratories, says the CDC’s 2019-CovRT-PCR test was developed to look for the presence of a nucleic acid found only in the SARSCov-2 virus. “It is not remotely accurate to say that the PCR test doesn’t differentiate between flu and SARSCov-2. It does not detect influenza. It only detects SARSCov-2. If both flu and Covid are circulating it would detect Covid, not flu” (Wroblewsky).

So, the gloom remains, the numbers of Covid cases have not been jacked up by the addition of flu cases, making it a pandemic, due to the inability of the PCR test to differentiate the two viruses. So, there is after all a pandemic without any question mark. It is quite clear that the commonly used PCR test is reliable, and its specificity is adequate for it to be used in the management of the Covid pandemic. This knowledge without any ambiguity is essential for all health workers in the world.

N.A.de S. AMARATUNGA