America needs to distribute hundreds of millions of test kits to identify people infected with the coronavirus now spreading around the world – a massive amount that far exceeds the number of test kits now available.
Vice President Mike Pence and Health and Human Services Secretary Alex Azar said Tuesday that over 1.1 million coronavirus test kits have been distributed across the U.S. and over 4 million more will be distributed by the end of the week. Unfortunately, that number is woefully inadequate for the task at hand.
Testing is critically important in preventing and treating the COVID-19 respiratory infection caused by the new coronavirus, known as SARS-CoV-2.
Several hundred million test kits for this new coronavirus need to be distributed to U.S. medical facilities and to other countries as well to be able to test a substantial percentage of our population, to test animals that could transmit the coronavirus to humans, to assess and monitor environmental sources of the coronavirus and to increase the global availability of testing.
We also need to deploy multiple types of tests from multiple manufacturers, and to repeat assessments using more than one type of test to ensure tests give accurate results.
Developing, evaluating and mass-producing several types of tests is necessary to ensure we find the best ones available. And we must do this at an unprecedented scale and with unprecedented speed. This should be an immediate national and international priority.
Testing and test kits are often discussed as if they represent a single entity. However, there are a multitude of ways to test for the coronavirus. Different types of tests provide important tools in the battle against this serious infection and contribute in unique ways to our understanding of this virus.
The type of test first used in China – where the coronavirus epidemic now underway began and remains the most widespread – is called an RT-PCR test. The initials stand for Reverse Transcription-Polymerase Chain Reaction.
The importance of this type of test is underscored by the fact that several Nobel Prize discoveries went into its development.
The RT-PCR test looks for specific genetic sequences that provide a genetic signature for the presence of the coronavirus. RT-PCR is rapid, sensitive and specific. But even RT-PCR tests can vary greatly, depending on which viral sequences are used.
In order to properly validate tests and ensure tests are of the highest quality, it is necessary to simultaneously use multiple types of tests on the same individual. This also points to the importance of having hundreds of millions of tests available.
People tested for the new coronavirus that emerged late last year should also be tested for the presence of other common respiratory infections, such as seasonal influenza and even other coronaviruses that may cause serious illness and death, especially when combined with epidemic coronavirus. This is necessary to determine if someone stricken with the new coronavirus has also been infected with other viruses, so the impact of the coronavirus can be properly evaluated.
The coronavirus outbreaks aboard cruise ships such as the Diamond Princess and the Grand Princess provide an ideal natural experiment to acquire critical information about the virus. In the best-case scenario, every person who was on one of the ships should have had multiple types of tests on a daily basis.
While it might seem a bit inhumane to turn these confined and imperiled individuals into human guinea pigs, the fact is that such tests would be far less onerous that what is endured by a typical hospital patient on a daily basis.
In addition, these travelers may have greatly benefitted from such testing by learning their status as a result of the early diagnosis of infection, or by earlier release from quarantine.
On top of this, the service these people would be providing for humanity would be profound and certainly life-saving. It would not be unreasonable to offer these individuals financial and other incentives.
Serial testing allows us to determine the earliest point at which the coronavirus is detectable and how long the virus is detectable before the occurrence of symptoms.
Combined with epidemiological data of when people interacted and contracted the infection, serial testing would allow us to determine the period when individuals first become contagious, when that contagion peaks, and when infected individuals are no longer contagious.
If the presence of the coronavirus precedes the period of contagion, serial testing would allow us to do “molecular quarantine,” whereby only individuals who test positive would need to be isolated. Instead of confining individuals we could simply test them and if the virus is present, quarantine them prior to the time when they can transmit the virus to others.
Polio provides an illustrative example where each symptomatic case that is detected signals the presence of as many as 100 cases of people infected with a virus but not showing any symptoms – yet who are in many cases still capable of infecting others.
We need to detect the people infected but without symptoms to prevent the spread of disease. It is critically important to determine the percentage of individuals with asymptomatic but transmissible infections.
One of the most frequent questions involves whether environmental sources – such as doorknobs – can transmit coronavirus, and also how long the virus can persist under various conditions. Again, like polio, environmental testing as well as human testing may be important. Therefore vast numbers of kits are needed for environmental testing.
RT-PCR has a great many uses, but it will not allow us to determine if someone was previously infected and if his or her immune system successfully fought off an attacking virus.
Global pandemics pose risks everywhere. So helping another country test for coronavirus will help reduce the number of infections we experience in the U.S.
The most useful test to determine viral immunity is a test that looks for the presence of antibodies to the virus. There are many antibody tests that are currently used for viral diagnosis.
The most common type is called an ELISA antibody test. This is the type of test is used for a wide range of infectious agents including HIV and the hepatitis C virus. ELISA stands for Enzyme-Linked ImmunoSorbent Assay and refers to the method by which coronavirus antibodies are detected.
For this reason, we need to make it a priority to immediately produce and distribute hundreds of millions of ELISA tests.
On the Diamond Princess cruise ship, for example, some passengers may have had the virus and cleared it so they were no longer contagious, and were therefore unnecessarily quarantined.
ELISA antibody tests may also be used to identify cured individuals with high levels of antibodies. The blood plasma of these individuals may serve as a life-saving therapy to the most seriously ill or as a preventive for the most vulnerable.
We can also identify individuals who have already had the virus but do not know it and therefore continue to live in fear.
Testing will also allow us to determine if reinfection is possible, if bodily fluids other than respiratory secretions may pose significant risks, and if the new coronavirus may cause persistent infections of the sort that are seen in Ebola and Zika virus infections.
If we hope to have effective treatment in the future for coronavirus infections, assessment of candidate drugs needs to begin immediately. Serial testing will be critical to determine whether such drugs are both safe and effective.
Another type of test that is not being carried out at a sufficient scale is a test to determine the genetic sequence of the entire virus. This type of testing allows us to follow the evolution of the virus.
It may be possible to determine whether specific genetic changes are associated with changes in the behavior of the virus – such as super-spreading or susceptibility to drugs. As an RNA virus, coronaviruses mutate at a high rate and such changes are expected.
This type of testing can also be used to do molecular epidemiology using changes in the sequence in order to follow the transmission of the virus from one individual to another and thereby provide a high-resolution picture of the patterns of viral spread.
An additional use of testing is to confirm the source of the virus in various animal hosts. One issue that has not received sufficient attention is the possibility that humans may be transmitting the virus to new animal sources, creating new reservoirs in new locations. Widespread testing will allow us to address this question.
It is important for the U.S. government and other economically developed countries to provide a vast number of test kits to underserved regions of the world. Global pandemics pose risks everywhere. So helping another country test for coronavirus will help reduce the number of infections we experience in the U.S.
Other types of testing may also provide important insights into the ways in which the coronavirus spreads and causes disease. For example, viral culture can provide insights into disease pathology, and antigen capture may provide rapid point of care assessment of infection.
The production of hundreds of millions of coronavirus tests may seem like an expensive proposition, but it will reap massive economic benefits in the long run.
Anything that curtails the epidemic domestically and abroad is likely to slow down or reverse the current global economic tailspin. Moreover, new technologies will be developed in conjunction with generating this expanded testing capacity.
Most of the expanded capacities have a dual-use in that they can be rapidly adapted for use with known infections and disease as well as emerging threats. Of greatest importance, however, expanding our testing capacity will provide a bulwark against disease and save untold numbers of lives.