Featured Article March 26, 2020

Why testing for COVID-19 is so important

This series of articles is about the COVID-19 pandemic, but specifically deals with  social distancing: what is it, why do we need it, how to do it right.  It is written by Edison Liu and Jill Goldthwait who are both medical professionals who have broad governmental, scientific, and management experience.  Goldthwait is an R.N. who has served in the Maine State Senate for 8 years and is currently serving in local government, Liu is an M.D. and is the President and CEO of The Jackson Laboratory. He previously led the scientific response for the country of Singapore for the SARS crisis in 2003. The opinions expressed are those of the authors and do not reflect policies or positions of The Jackson Laboratory or the Town of Bar Harbor.   

Liu lab
JAX President and CEO Edison T. Liu, M.D. Photo by Tiffany Laufer.

 

Social distancing, travel restrictions, shelter-in-place and lockdowns are all blunt instruments in fighting a pandemic.  This is because all of these approaches assume everyone is suspect in carrying the virus, and therefore the interventions target everyone.  This is further complicated by the fact that as at the same time COVID-19 is raging, there is the usual seasonal influenza resurgence.  The symptoms are similar, so distinguishing the two ailments – influenza versus COVID-19- by clinical examination is nearly impossible.  Under these conditions, we are fighting blind.

 

But what if doctors could pinpoint who among the people with cough and fever have COVID-19, and even identify who are asymptomatic carriers of the virus?  These individuals can be isolated early in the course of their illness when the viral load and viral shedding is relatively low, at a time when treatment with new anti-virals is most effective.  The key is whether there is a test to definitively tell if you are shedding COVID-19. 

 

Enter polymerase chain reaction (PCR), a molecular approach that can detect remarkably minute amounts of viral nucleic acids with high precision from any biological sample.  The diagnosis of infectious diseases has been revolutionized by PCR and indeed within the first few weeks of the COVID-19 epidemic the virus was sequenced and a diagnostic test for COVID-19 was produced.

 

We can now determine who has COVID-19 and how much virus is being shed by the patient. Importantly, with PCR and DNA sequencing, the origins of every virus can be traced, and we can determine how the virus was passed from one person to the next.  This molecular contact tracing is used to identify the source of infections and to detect critical mutations that may alter the biology of the virus.

 

COVID-19 testing, when integrated with social distancing policies, becomes a formidable weapon against the pandemic.  This is how it works: In the first instance, all patients who need to be hospitalized will be tested for COVID-19.  Those with influenza are treated with antivirals specific for the flu, but those with COVID-19 are isolated with special procedures to prevent the spread of the virus. This is essential to protect nurses, doctors and other health care professionals from being infected.

 

Second, all individuals with COVID-19 symptoms in the community must be tested.  The majority of them will not have a COVID-19 infection but the ones who do require much more intense isolation and observation than those with the common cold or seasonal flu. In this manner, when appropriate anti-COVID-19 drugs are developed, only those truly affected individuals will receive them. 

 

Just how many people with symptoms have COVID-19?  No one really knows the number because random testing in a population has not been implemented and often only patients with the most severe symptoms are tested. But a rough estimate is that around 10% of those tested will be positive (https://ourworldindata.org/covid-testing).  What this means is that for 90% of the suspicious cases, strict quarantine measures would have been overkill.  It becomes very obvious why widespread testing significantly enhances pandemic control while limiting the disruption.

 

Third, a random selection of people without symptoms should be tested during this pandemic to get an idea of how many asymptomatic people who test positive could infect others. Even though this approach may not result in any direct action at this time, it will greatly inform medical planners and policy makers as to how to deploy future vaccination and social distancing programs. With this information, scientists can understand why certain people succumb to the disease whereas others are asymptomatic. Also, we have experience in the past that knowledge of the reasons for these clinical differences can lead to novel treatments.           

 

The success of those countries where the COVID-19 pandemic appears to be being controlled - China, Korea, Taiwan and Singapore - has been attributed to aggressive early testing regimens and the willingness to isolate affected individuals.  This is sometimes called the “test, treat, and track” strategy for COVID-19.  Test extensively, treat by isolating the affected individuals only, and then track through contact tracing all possible infected individuals and isolate them so they cannot further infect others.  China’s problem at the beginning, and one of the main reasons why the epidemic spread so quickly, was because their authorities initially denied the problem existed until after it had spread.  It was only when aggressive testing and stringent isolation policies were imposed that China began to control the epidemic.  

 

How well is the United States doing in deploying COVID-19 tests?  In truth, compared to other advanced countries, we are doing pretty poorly.  As of March 20, 2020, the United States has conducted only 314 tests per million people (with 330 million people) as compared to 12,738 per million for South Korea (with 51 million people). This is a 39-fold difference in testing activity comparing South Korea with the US. In fact, we are even behind the province of Guangzhou in China and sandwiched between Finland and Vietnam in terms of the frequency of testing [https://ourworldindata.org/covid-testing].

 

Our inaction out of the starting block clearly set us back.  It has left us with only one remaining option — to isolate everyone – to close stores, restaurants and businesses, and to force everyone to shelter at home.  Commerce stops, and the economy falls. But without robust testing, this is all we’ve got.  Although this is being rectified with the recent passage of the CARES (Coronavirus Aid, Relief and Economic Security) Act, it is now a foot race between the pandemic spread and our ability to test.

 

As with managing any scarce resource, first, we will need to prioritize where to apply the test to have the greatest impact, and second, we will need to have the discipline to execute this delivery well. Right now, the prioritization must go to workers who have critical functions in helping our communities to fight the COVID-19 pandemic such as hospital workers, police, EMT first responders, grocery store and cleaning staff. This should also include workers in critical infrastructure: medical production, COVID-19 research, manufacturers of gloves and gowns.  Limiting the spread of the COVID-19 in these populations will ensure the safety of all.