It’s a story as old as the pandemic: “He tested negative, but I’m sure he has it. What should I do?”
The topic has come up repeatedly — with at-home rapid antigen tests (RAT) and the more sensitive PCR (polymerase chain reaction) and molecular tests like Lucira. Not long ago, it came upon in a Facebook group, where the anonymous poster wrote that she and her daughter got Covid for the first time, but her husband, who has been sick for weeks with the same symptoms, repeatedly tests negative. His doctors say he has it, although he is negative, she added.
Others chimed in with similar stories — of people testing negative, repeatedly, though their symptoms and their potential exposure in a household or workplace of others testing positive suggests that they almost certainly have Covid. And since many parts of the United States, even the world, are seeing a surge of Covid cases, it’s worth knowing.
The rapid at-home tests are generally considered to be less accurate than the PCR tests, though PCR tests can also give false negatives. And because PCR tests are now harder to come by and can easily cost money either in the form of a co-pay or paying for the complete test, a lot of people are using only the rapid at-home tests — despite the fact that they’re not as accurate.
Her men are never positive
One woman wrote: “A couple men in my family do not test positive on home tests either. They assume they have covid as well, and if you can I’d get a PCR for confirmation”
I asked her if I could use her comment, and she said yes, then wrote:
“I can add to it a bit. Two men in my family, my dad and brother-in-law, don’t test positive on home tests. I’ve been reading anecdotal accounts online of home tests not working as well lately. It makes me anxious that if someone in my family has covid again we won’t catch it in time to keep others from getting sick, if we even find out it’s covid at all. I really hope that home tests continue to be updated to pick up the most current strains of covid.”
I asked what brand of test, and she wrote: “I don’t know the brand of the tests, but the only tests they have gotten recently while assuming they’re covid+ is from the USPS free tests. Which we know are about to truly expire much past the original expiration date very soon 
While they are testing negative they have symptoms and are in households where others have covid, so it’s pretty safe to assume they’re sick with covid as well”
(All of these comments are used with permission from the commenters.)
‘We never trust a negative test’
One woman wrote that when her husband and kids had Covid, she never tested positive despite having all the symptoms.
There are also a number of people who are negative on the less sensitive rapid tests but positive on the PCR test, as has been true since the beginning.
Another: “My husband never tested positive despite multiple rapids and multiple PCRs. But he had all the symptoms at the same time as me, and I tested positive on PCR (I also never got a +RAT). Despite the negative tests, his doctor diagnosed him with long covid when his symptoms, primarily extreme fatigue, persisted for almost a whole year. So, yes, been there, done that. We never trust a negative test.”
Dr. Michael Mina, an epidemiologist who is now head of e-Med and a consultant, wrote on Twitter: Please note – If you use expired rapid antigen tests – here’s how I think about interpreting them 1) If Negative – do not trust it – especially if control line is faint / absent BUT 2) If Positive – trust it – *very likely* true positive. “(short thread) 1/”
He added: “I do *not* recommend using expired rapid tests. This thread is regarding those who do happen to use them because it’s what you have. And to reiterate, if you do use an expired one – only trust it if it is positive.”
Related: People are just not testing
In some cases, people are simply not testing.
One contributor wrote: “My husband just texted me that the receptionist at his work is sick. She claims it’s not COVID or flu just a winter cold, with a lingering cough. My husband has to go into work this week and next, and this is what we have to deal with right before Christmas. I hate that no matter what we do, it doesn’t matter because other people suck.”
Social media is full of reports of people who are not testing because they’re sure they don’t have Covid — or that they know they have it, but they’re being told to go to work anyway.
Sometimes people are testing too early, which can result in a negative test — and then a positive one a day or two later. One woman Tweeted: “My best friend was exposed to two people with COVID and started feeling really sick so she took a COVID test. Negative. She still wasn’t feeling well a few days later so she took another. Positive.”
Another story is circulating about George Clooney, the actor and director, who attended a cast and crew party in London before shooting the movie “The Boys in the Boat.” All attendees were tested and vaccinated. Afterwards, 17 of the 18 people there got Covid.
Why aren’t the tests reliable?
Early in the pandemic, we discussed the topic of inaccurate tests with Dr. Ryan Neuhofel, from NeuCare Family Medicine in Lawrence, Kan.
“This is another thing that is not unique to coronavirus,” he said in a Zoom interview. “I would consider myself a medical conservative in the respect of not relying too much on tests, because they’re not perfect. Interpreting diagnostic testing is always complex. The public definitely doesn’t understand that. Far too many people think a doctor doing a careful history and physical exam to reach a diagnosis is ‘just guessing.’ We should get the test to confirm things when needed and feasible. But that is not straightforward in many circumstances — often there is not a definitive 100% test. It’s a combination of factors that lead to a doctor making a diagnosis.
“If the test is negative, Is it possible they still have it? Absolutely. Maybe you could test them again, in three days, it would be positive! This is kind of like a mind-blowing concept to the public. This is not unique to coronavirus. This has been true of influenza. And this is where we have to make a somewhat of a preliminary or clinical diagnosis.”
In other words, the doctor’s view, based on a clinical picture — symptoms, history of exposure, and so on, is the best thing for a diagnosis. A test is useful, but it’s not the only factor.
Are you doing the test right?
There could be a lot of reasons for inaccuracy. You didn’t do the swab right, or didn’t use the buffer solution right, or you didn’t wait long enough for the little line to show.
The test is expired.
It was exposed to extreme cold or heat.
You test too soon — the first day after exposure is too soon — or too late.
There may be other factors. One woman wrote:
“1) swab back of throat and cheeks before nose after 30 mins w/ no food or drink?
“2)if he used a CPC mouthwash or toothpaste, wait 12 hours before testing
“3)try w/ molecular like Lucira?
“4)some newer variants concentrate in gut and some suggest testing toilet water after a 
“
What you can do
Knowing this, what can you do?
Check the expiration date before using. Here’s the FDA page with expiration dates. If it has expired, it’s not reliable. (Well, O.K., even if it hasn’t expired it may not be reliable.)
If it has expired and gives a negative, don’t believe it. If it has expired and gives a positive, believe it.
If you’re negative and you still have symptoms, test again. The RAT results are often negative early and then become positive by day 4 or 5.
Test for flu and RSV — Covid isn’t the only thing going around. Also some people are getting nasty colds. But remember — you could have Covid and the flu or another virus at the same time.
Make sure you’re following the manufacturer’s instructions on every detail: Taking the swab. Using the buffer solution, if needed. Waiting long enough — but not too long — before reading it.
Make sure tests are not exposed to extreme heat or cold, or too much direct sunlight.
Note the above comment on food, drink, mouthwash and toothpaste.
Even after all of that, it’s possible that the test just isn’t accurate.
You can go get a PCR test — they are supposed to be more accurate — though they are becoming harder to come by, and it’s likely that you will have to pay, depending on the circumstances. Also, they too have been known to give a false negative.
We have heard about testing the water in the toilet. There’s not a lot of science on this, but anecdotally, people are saying that a negative nose and throat test is accompanied by a positive wastewater test.
Perhaps you’re the only person in your household who tests negative, while everyone else is positive. Assume you have Covid, to protect yourself and others. Urge others to be cautious too.
Don’t rely on any test for certainty. Since the beginning of the pandemic, clinicians have told us that tests are not always reliable, even if we might want them to be. Doctors say the clinical history and presentation — symptoms, exposure — are more important in determining if someone has Covid than just the one data point of a test.
