Why a single test is not good enough

The September 29th Garden Island describes two COVID cases that were picked up as positive on Kaua‘i. It describes how the cases were related to mainland travel but fortunately neither case was contagious during the time they were traveling to Kaua‘i. The article states they became contagious while they were in quarantine and therefore did not pose a risk to the other travelers. That is very good news but it is important to point out that as of October 15th this good news story could have turned into a very bad news story.

Those two people were in quarantine because that is the law at this time. After October 15th, they could have received a preflight COVID test. It would have been negative because they were apparently in the incubation phase and their COVID tests would still be negative. They would have then come off the flights and gone on with their everyday activities possibly exposing a lot of people because after October 15 if you have a negative preflight test you do not need to quarantine! Please note that with a proper two test system they most likely would have been picked up prior to going out into the community as they were with our current quarantine system.

The reason the single preflight test will miss so many people who are going to become contagious has become a political football with state government officials and others downplaying the risk of a single pretest. The reason that a single test could miss 30-40% of those who may become infectious is an important point for us to reach a scientific agreement on.

The science is this: the natural or common course of this illness consists of a 3-4 day incubation (or longer). The incubation period starts when the virus enters your body and begins using your cells as little factories producing more and more of the virus. For the first three days of incubation, no test we currently have can detect the virus because the numbers are so low. On day four the virus often explodes into greater numbers and estimates are that 33% percent of tests might be positive on day four, meaning 67% of those tested will still have a negative test. On days five to six, the viral load may be quite high and the person may start to have symptoms, but even by day eight, 20% of the tests could be negative. Even though people can remain very sick for a long time with this virus, by day 12-14 most people are much less contagious to others.

They may remain quite ill even as the virus is eliminated since the virus can damage so many organ systems. For many it is like a hurricane went through leaving a wake of destruction.

To review…. there are about 12-14 days from the day one catches the virus until they are much less contagious. For the first four of those days you will most likely have a negative test even though the virus is in your body and your test could even still be negative on day eight. That means that if you test hundreds of people with a single pretest, one third or more of those people may have the virus and the test will not show it. In addition, anybody could catch the virus after their test, in the airport, or during the long flight.

Many places show that high percentages of people who are tested have the virus but what we really don’t know is what percentage of those who want to travel will have the virus. We do know that many nations around the world are not letting travelers in from the United States because our disease is so widespread. If we estimate that one percent of those traveling may have the virus, we could be letting in 32 infected people for every 10,000 arrivals. If we had 1000 visitors a day that would be 100 people a month bringing infections into our community.

The safest way to contain the virus is a well-monitored 14 day quarantine. If we want to shorten the quarantine, we could consider requiring a negative pretest and at least a negative second test after 6-7 days in quarantine. It is not as safe as 14 days in quarantine but much safer than a single pretest with no quarantine. As was pointed out in another article in the Garden Island on Sept. 29, thanks to our mayor, district health officer and our community efforts we have been one of the most COVID- free counties in the world. As I understand it, Mayor Kawakami and Dr Berreman are also in support of a two test system.

There are a growing number of people who can work remotely, want to come to a safe place, and will be happy that we are remaining so strict. My hope and suggestion is that we stay strict, go to no less than a 7 day quarantine and require at least two tests. I think we should also give a lot of consideration to the advantages of attracting visitors who want to stay a while and want to be as safe as we have been. Consider writing to the Governor and Lt Governor; a single pretest and no quarantine is simply too dangerous.

This column represents a sharing of information. No content on this column should ever be used as a substitute for direct medical advice from your doctor or other qualified clinicians.


Lee A Evslin, MD is a Board Certified Pediatrician and Fellow of The American Academy of Pediatrics. He was a former healthcare administrator on Kaua‘i and periodically writes a column for The Garden Island.

  1. Major Lee Hung October 1, 2020 1:45 am Reply

    So masks, distancing and cleaning doesn’t work?
    What the good doctor isn’t telling you is that the cycle threshold used for the pcr test is 37 or 40, depending on lab. This means that every 3.3 cycles is equivalent to a ten fold increase in viral RNA. Because of such a high cycle count many positive tests were being reported even though the patients have recovered. The tests with a high cycle threshold can detect non viable viruses and even fragments of RNA. Additionally, it is widely believed that there may need to be a minimum amount of viable virus for onward transmission.
    Doctor if you really want to inform the public then please do so and stop the fear tactics.

    1. Thomas Ohana October 1, 2020 5:17 pm Reply

      For a known exposure to a positive person, a single test is definitely not enough. Even then, an exposure (unmasked) to a positive person is about 0.45% for non-household members and about 10% for household members. (https://www.cdc.gov/mmwr/volumes/69/wr/mm6909e1.htm)

      Known exposures should have repeat testing. For the normal, masked and socially distanced person, the chance of secondary transmission is even lower. We need to balance risk/benefit ratios in a realistic manner that allows us to resume the new normal way of life. If Hawaii can make a second test available easily, it should be done. As it is, Hawaii isn’t making the first test easy, but mainland agencies are doing so in order to restart travel in as safe a way possible. Tests and tracing are the key; masks and distancing are the doorway.

  2. a pediatrician knows best? October 1, 2020 2:59 am Reply

    all this fuss over tests. if this virus is so deadly, why do we need to test repeatedly to see if we even have it?
    and if we place this much weight on positive test results, then the converse is true: negative results are just as worthy of this unwarranted attention.
    As for Dr Evslin, if he’s so fearful, he should stay locked inside his home. the rest of us have lives to live.

  3. Lisa October 1, 2020 6:36 am Reply

    My father went in today for pancreatic surgery on the mainland after ONE test to confirm he was negative for Covid. Yet, the island wants two tests for visitors and a quarantine buffer? How many visitors, essential workers and residents have actually brought in Covid and been diagnosed while in quarantine (without any pre-flight test)? Almost none. This two-tier system will be impossible for anyone to enforce, even assuming there are sufficient testing supplies (which is totally unclear), and it will drive everyone away from Kauai for good. It will be the last nail in the coffin for our economy.

  4. PCL October 1, 2020 7:09 am Reply

    Fantastic. This will probably solve the coronavirus problem and make Kauai a premier high end tourist destination for the entire U.S. and probably foreign countries. Go for it. Thank you Mayor Kawakami and Dr. Evslin. Without this we will be going into periodic lockdowns.

  5. WaimeaResident October 1, 2020 7:13 am Reply

    The virus will still make its way here. The testing will never catch all.

    No, I’m not a doctor. And respectfully, the author is not an economist.

    Election virus.

    Free the young, protect the elderly and weak. Isolate those of high risk and let’s open up.

    1. How October 3, 2020 5:45 am Reply

      Can anyone explain how you protect the high risk people and fully open at the same time?

  6. so scary October 1, 2020 8:17 am Reply

    the covid is so scary, few know if they even have it. with symptoms like that, we’re all doomed!

    1. I saw a Vampire once October 1, 2020 11:41 pm Reply

      You will know. For the unsuspecting ones. Feeling sick. At worse case scenario, the virus hits exponential. Meaning it spreads rapidly after a certain point. Then death. But that may take some time to happen. We still have our body defense mechanism to defend against any viral infections.

  7. Paulo October 1, 2020 9:19 am Reply

    Thank you Dr Evslin. Looks like we might be getting the 2 tests but possibly from what you have told us, there should be a longer period in between the tests and the visitor should be quarantined for no less than 7 days.

    Hopefully the Mayor and the Governor will consider that 7 day time period.

  8. Reina October 1, 2020 9:55 am Reply

    I, and I am sure many other people are really hoping and praying that the governors are listening and reading these posts, especially from the doctors
    That have made it crystal clear that doubled testing needs to be happening along with quarantining.
    The numbers speak for themselves.
    It only takes a couple of people bringing it home to their families after exposure.
    it’s almost inevitable so the only chance that we have is to test on both sides and quarantine as well and even then the risk is high of infecting the community.

    The Island it too small for this..

  9. Thomas Ohana October 1, 2020 5:44 pm Reply

    A single test is NOT good enough, if you have had a SIGNIFICANT exposure to COVID. What is a significant exposure? All hospitals on the mainland agree that it is 1) less than 6 ft, 2) more than 15 minute, 3) unmasked or improper PPE exposure to a positive person. These exposures receive dual testing and a 14 day quarantine in all our hospitals.

    An exposure to a negative, asymptomatic person is not treated in the same way. While there “may” be a positive person that a one-test system misses, the chance of having a positive exposure on an airplane with everyone testing negative and everyone masked is slim. Whether you are exposed enough to need a two-test, 14 day quarantine is up to YOU. If you follow the 3 steps above, your exposure would likely not be considered significant and the protocol would not be suggested.

    As someone who works with COVID on the mainland every single day, it is difficult to get infected if you follow the three steps above. It might be “best practice” to do dual testing and a 14 day quarantine, but it is not practical and not done for everyday contacts.

  10. I saw a Vampire once October 1, 2020 10:30 pm Reply

    Can you set an injunction on the 4 uh football games held at Aloha Stadium? 2020 Hawai’i Warriors. This year. Your DOH

  11. I saw a Vampire once October 1, 2020 11:16 pm Reply

    10.000 arrivals. That is 320,000 infected cases in just a nick of time. At 100 million visitors, this will be 320,000 infected cases. That is in 10 years time. If a vaccine doesn’t come out by then.

  12. Steve Martin October 3, 2020 8:24 am Reply

    Two tests aren’t guaranteed works. What’s guaranteed is that tourists have many choices of where to vacation and the more red tape you put on the subject the more they will search for less red tape. This is nothing more than bitting the hands that feed us. Those in charge are doing nothing but making our situation worse. The world is full of places to vacation and the more restrictions put on people the more they will vacation somewhere else.

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