COVID-19 Testing: Vitally Important Despite Vaccines

GIVEN THE UNIQUENESS of the severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2, and the COVID-19 disease it causes, it is little surprise to those on the front lines of medical care that there is considerable confusion among patients regarding vaccines and testing. The rapid ramp-up of research into the then-novel coronavirus inevitably led to equally rapid updates to our understanding of the virus, in turn leading to often jarring shifts in government policies regarding the pandemic. In addition, the messy, imperfect and all-too-human reality of scientific research led to both a sincere misunderstanding and calculated mercenaryism on the part of elected officials charged with minimizing the human toll of the pandemic.

A century of towering medical advances led much of the public (and the mainstream media) to view medical research as an unwavering straight line forward. However, the highly contagious nature of the SARS-CoV-2 virus brought the haphazard reality of science into the average person’s daily life in a tangible way not seen since polio was conquered more than six decades ago. More troubling, those for whom political affiliation is a defining part of their self-identity have divided themselves into two camps, neither of which is particularly open to a physician’s counsel: 1) Those who think their belief in and support for science lends them an expertise they don’t actually have, and 2) those who are predisposed to distrust almost anything attributed to science.

It is a situation that puts physicians in the discomfiting position of having to provide guidance to patients residing on a spectrum ranging from angry denial to the contentedly self-diagnosed merely looking for affirmation. And when it comes to convincing patients of the importance of being tested for COVID-19 following a confirmed exposure or exhibition of symptoms, that can be a steep challenge.

Types of Testing

Two main categories of tests look for COVID-19: viral and antibody (Figure).¹ Viral tests ascertain whether patients are currently infected with the SARS-CoV-2 virus. Antibody tests determine if patients had a past infection.

The most common tests currently in use are viral tests that help identify contagious patients so they can self-isolate to prevent further spread of the infection. Viral tests work with samples taken from the throat or nose, and look for molecules unique to the COVID-19 virus.

There are two types of viral tests: rapid and laboratory. Rapid tests include home tests that can be self-administered and provide results in less than 20 minutes. These tests, including the newly available self-administered home tests, are generally antigen tests. Antigens are substances in a virus or bacteria that trigger the body’s immune response. Rapid tests take approximately 15 minutes once the sample is applied, and they cost about $10 to $15 each. In these tests, the test strip is coated with laboratory-created antibodies specific to the body’s response to a COVID-19 infection. If these antibodies encounter any antigens from the SARS-CoV-2 virus in the sample from patients, they will react and a colored line will appear on the strip indicating a positive result. However, these tests are not as accurate as lab tests, and they can provide false-negative results if patients are early in their infection.² Follow-up studies have found rapid tests are between 64 percent to 79 percent accurate.³

Laboratory tests use a technique called polymerase chain reaction, in which any RNA is amplified 30 or 40 times before the sample is tested for the SARS genes. It is considered to be 100 percent accurate,² but it can take several days from when a sample is taken until patients and/or their ordering physicians receive the results. And, they cost up to $100 per test.

Antibody tests are different from antigen tests that look for the presence of pieces of a virus. Antibody tests, or serology tests, seek out the immune system cells produced by the body to fight a COVID-19 infection. These tests can’t indicate a current infection; they can indicate only if patients have been infected in the past.⁴

While some antibody tests can detect antibodies from a vaccine in addition to a previous infection, researchers caution that because there are different tests employing differing technologies, some tests will only indicate a previous infection, while others will also show antibodies from vaccines.⁵ In addition, tests may be inaccurate for those whose immune systems are weakened. For these reasons, the Centers for Disease Control and Prevention (CDC) currently recommends against using an antibody test to determine if a vaccine is offering protection.⁶

‘But I’m Already Vaccinated!’

Major resistance to getting tested often comes from patients who have received both the two initial COVID-19 vaccines, as well as the booster.

Undeniably, the 20th century was the century of medical miracles. From eradicating smallpox to nearly eliminating polio, the development of the modern vaccine removed huge swaths of human suffering from our lives. However, those earlier vaccines also gave the public an unrealistic expectation of vaccine invincibility. This was compounded, unfortunately, by politicians (and not a few public health officials) who initially touted the COVID-19 vaccines as a sort of magic bullet that would end the pandemic — making promises before we had had enough time to measure the efficacy of these brand-new vaccines. As the primary face of the medical industry, physicians and other front-line personnel have found themselves bearing the brunt of the public’s frustration. Saying “no” to further testing seems the only way for some patients to register that frustration.

Patients often need reminders that many familiar vaccines require multiple doses, or boosters, to help the body’s immune system continue to fight an infection. Tetanus and chicken pox/shingles are just two diseases to which most patients are already accustomed to having regular booster shots to restimulate the body’s immune response.

For this pandemic’s virus, the flu is a more fitting example, since influenza viruses are prone to the kind of rapid mutations researchers are seeing with SARS-CoV-2. Obviously, every virus has its own genetic makeup that makes it more or less susceptible to chance random mutations, and unfortunately, SARS-CoV-2 is higher on the list than relatively stable viruses such as measles and poliovirus. Further, having tens or hundreds of millions of infected hosts also increases the odds of a chance random mutation just through the sheer number of SARS-CoV-2 viruses mutating in the bodies of the infected. Even if the odds of a chance mutation during any individual replication are low, when there could be multiple billions of replications in a single patient⁷ and we calculate that against a global pandemic, clearly there are going to be mutations. And we can only find and track those through testing.

Once patients understand that not all viruses are alike, and thus not all vaccines work alike, they may be more receptive to the notion that getting tested is a common-sense step to protect their health — even after going to the trouble of getting vaccinated.

And, now that researchers have found that SARS-CoV-2 has had at least three significant mutations (Delta, Omicron and BA.2) that are not fully addressed by the earlier vaccines, it is likely more mutations will follow. This means vaccines will need updating, and people will need boosters, as well as ongoing testing, since we have experienced that even those who have received all the vaccines can still become infected and contagious.⁸

As such, even those already vaccinated should undergo testing if they have a confirmed exposure or are exhibiting symptoms consistent with COVID-19 — particularly if they live or work with people with compromised immune systems or are in another high-risk category. Even for the previously vaccinated, a positive COVID-19 test should be followed up with the latest isolation recommendations from CDC.⁹ Unfortunately, this is news nobody wants to hear, especially now when COVID-19 fatigue is running nearly as strong as the pandemic itself.

Long COVID-19

Every new infectious disease brings with it a host of unanticipated health challenges, and COVID-19 is no different. While most people apparently recover fully and quickly from COVID-19, a small percentage develop lingering symptoms of varying severity and type following infection. This is referred to as “long COVID-19.”¹⁰

With recent research suggesting long COVID-19 in many patients is likely the result of the body’s immune system overreacting to a COVID-19 infection,¹¹ testing to determine whether a patient has had COVID-19 can assist in determining whether the observed and reported symptoms are, indeed, consistent with a diagnosis of long COVID-19. The antibody, or serology, test would be the appropriate test in this instance.

A positive result might then lead to further testing since a lupus-like condition seems behind these cases of long COVID-19. Specific cells known as autoantibodies, which attack the patient’s body instead of the virus, are the suspected cause. Other patients seem to suffer a resurgence of Epstein-Barr virus, which may have been dormant but can become active again during COVID-19 infections while the body is busy fighting the virus.¹²

Because that same research shows other patients have long COVID-19 caused by a lingering COVID-19 infection, a negative antibody test can be followed up with an antigen test to look for a current infection. Many of these patients have found relief from long COVID-19 by receiving a vaccine, which seems to help the body eliminate the remaining SARS-CoV-2 virus.

Diabetes seems to be the underlying cause in the remaining patients with long COVID-19.

Other Diseases

Another new syndrome associated with COVID-19 in children is multisystem inflammatory syndrome. An antibody test can determine if patients have had a past infection of COVID-19.⁴

In addition, any patients with a heightened risk factor — untreated high blood pressure, diabetes, obesity, a compromised immune system — should be tested after exposure or exhibiting symptoms consistent with COVID-19. These patients have a higher chance of developing serious health problems, and knowing if they have been infected will allow their physicians to monitor them and quickly begin aggressive treatment in the case of a positive test result.

Body of Knowledge

Due to the high toll COVID-19 has taken around the world, and the necessity of focusing on producing vaccines, widespread antibody testing for COVID-19 has not been accomplished in most jurisdictions. We do know that for many people, perhaps a majority, a COVID-19 infection is accompanied by relatively minor symptoms that mimic other less-serious diseases such as the flu or a common cold. And another significant number of people who contract COVID-19 are wholly asymptomatic.

Therefore, researchers working on treatments for COVID-19 still lack a firm data set on how many people have contracted it. This is an important piece of information for epidemiologists studying how COVID-19 spread initially, and how current (and likely future) variants spread, as well as how many people have some natural immunity from having previously contracted the disease.

When patients use a home test, they should be encouraged to share the results with their physicians to assist in building a fuller picture of the pandemic.

The Road Ahead

Despite the mainstream media’s often polarized reporting, the percentage of the population that is vaccinated continues to increase. If, as many researchers now believe, COVID-19 is here to stay and will become endemic, much like influenza, then getting an annual COVID-19 booster will become just another medical discussion patients have with their doctors each year — with the decision based on the medical profile of each individual patient, rather than the raging political debates of the day.

Getting patients into the habit of being regularly tested, however, may be a tougher sell — simply because there is no existing program against which patients can compare. Regular testing for an infectious disease on a large scale is a new phenomenon, unique to COVID-19, and it may well take months and years of gentle, consistent persuasion to convince patients that testing is merely another necessary, if annoying, fact of life.