the rush was on to make more testing available

As the Coronavirus pandemic evolved in the US in the early part of 2020, the rush was on to make more testing available, and to develop new and better types of test kits. Much has been written and discussed in the news about the accuracy and efficacy of some types of testing, and the reliability of the Covid-19 numbers reported. Two primary types of tests have emerged as the most accurate – Antigen tests and Molecular tests. Both are collected via nasal swabs.

Two primary types of tests have emerged as the most accurate – Antigen tests and Molecular tests.

False Negatives

Many factors come into play when assessing the accuracy of testing – but to make it simple, the test itself is only as accurate as the collection method. Antigen tests are found to be highly accurate when positive, but negative results may need to be confirmed with a molecular test, especially if the patient is symptomatic. It is important to note that no test is 100% accurate all the time. (source: FDA.gov)

Factors that impact the test’s accuracy.

There are 4 factors listed by the FDA that impact the test’s accuracy.

  • The swab does not collect enough material from the nose or throat to detect the virus.
  • The swab or mucus sample is accidentally contaminated by the virus during collection or analysis.
  • The nasal or throat swab is not kept at the correct temperature before analyzed.
  • The chemicals used to extract the virus for testing may not work correctly.

Of these four, can you guess which is the most common problem? You guessed it, number 1 – the swab does not collect enough material. This can result in false negative tests, which may delay treatment for vulnerable individuals.

Can you guess which is the most common problem with testing? You guessed it – the nasal swab does not collect enough material. This can result in false negative tests, which may delay treatment for vulnerable individuals.

Decidedly UNCOMFORTABLE

The nasopharyngeal swab, as most have heard, is decidedly UNCOMFORTABLE. It involves sticking a swab deep into the sinuses and holding it there for several seconds. Some patients have a hard time tolerating this testing procedure, and it is especially difficult for children.

Shortages led to shorter swabs

At the same time that testing was being rapidly developed and deployed, the US was faced with an unexpected bottleneck – a shortage of swabs. This led to rapid approval by the FDA of some shorter, Q-tip style swabs being used to swab the nares (nostrils) instead of the deeper swab. The patient was more comfortable, and the swabs are more available, sounds great! But are these shorter swabs the most accurate? Preliminary studies say no – they may be prone to larger numbers of false negatives.

Are shorter swabs very accurate? Preliminary studies say no – they may be prone to larger numbers of false negatives.

Not enough virus to detect

According to the latest information, synthesized by the NY Times here, Dr. Ravindra Gupta, a clinical microbiologist at the University of Cambridge states that these shorter swabs with less painful tests aren’t always accurate. The viral load is often much less in the nose or throat, making the long swab in the sinuses necessary to get enough of the virus.

So, are we all just stuck getting stabbed up the nose? Not necessarily – innovation is at its peak right now, with many different types of tests being developed.

Looking to the near future

So, are we all just stuck getting stabbed up the nose? Not necessarily – innovation is at its peak right now, with many different types of tests being developed. Saliva, serology (blood), combinations of virus and antibody testing, and better chemicals to improve the accuracy and rapidity of the testing are all in development!

If we have learned anything with the Coronavirus, it is that the news today will be replaced by something different tomorrow. Patients and clinicians alike can most certainly look forward to better days ahead when it comes to testing at the point of care and receiving accurate results.