Covid-19 Test Accuracy
Covid-19 tests are unreliable, but even more alarming is the risk for false-negative results. What is a false negative? A false negative is when you get a negative test result but you are actually POSITIVE. The rapid tests are only approximately 50% accurate. So, why are they so common? The rapid antigen tests are less expensive and provide rapid results in less than 20 minutes. Talk about immediate gratification, but this does come at the cost of losing accuracy.
The PCR test is more reliable, but nothing is certain with a virus we know so little about. UC Davis Health still reports 20% false negatives. The PCR sample is sent to a lab, but things can happen while it is being transported (temperature is not regulated, samples are getting lost, etc). I am not impressed with these tests either. Not only do we know so little about the virus that the labs are not very accurate, but the mishandling of samples contributes to even less accurate results.
I know 2 people whose PCR send out labs were lost, a physician whose swab was mixed up with a different physician, and other healthcare workers who were reported “positive” results but were never swabbed. These healthcare workers completed the paperwork and were sent away without being swabbed because they did not meet the “criteria” of the testing center, but were later reported that they had positive COVID results. Imagine the headache of proving you are COVID negative before you can return to work, but you were never swabbed in the first place 😱
Nonetheless, the numbers as of January 2021 are increasing. We may not have mastered detecting the virus, but it definitely is a real threat to all of us. I am currently recovering from COVID. I have two close friends who are battling COVID after having false reassurance from a negative COVID test.
Here is my personal story of how false negatives are contributing to COVID spreading. My friend, John, had mild cold symptoms that did not match with typical COVID symptoms. He was COVID tested per company policy, and returned to work. 6 days later, he was still not feeling well and his symptoms were slightly worse, again he tested negative for COVID. John told everyone who attended his New Years’ party that he did not feel 100%, but he had two negative COVID tests within the past week. Of course, everyone felt reassured and attended. 10 days into his symptoms, after the party, John lost his taste and smell. Of course, he was retested and horror of horrors, he was COVID positive. Within a week, the party-goers all started to come down with COVID symptoms, and one-by-one they were now testing positive.
My professional advice related to the COVID tests, positive results guarantee you positively have COVID. A negative result could still mean you are COVID +. Many physicians are testing patients for both flu and COVID. If they have COVID symptoms and the flu is negative, they are treating it as a positive COVID result.
Why are COVID Tests Unreliable?
The accuracy of Results are affected by
- Quality ….. Was a good sample obtained?
- Timing …. when you get the test
- Unknowns …. We still know so little about the virus
When a healthcare professional gets a sample of your saliva or nasal swab, did they get a good sample? The “quality” of your sample could be affected by their technique. Getting a nasal swab is not a pleasant experience. If the swab does not go into the right place, your results will not be as accurate. Now, let us say your sample was obtained with a perfect technique. Your swab was the perfect sample, but the viral load is not high enough to be detected. You could in fact have the virus, but test negative under these circumstances as well.
This brings me to the second thing everyone needs to consider before getting a COVID test, timing. What do I mean by timing? First, when were you exposed? Second, when did your symptoms begin? For example, if you are tested on the day you were infected, your test result is almost guaranteed to come back negative, because there are not enough viral particles in your nose or saliva to detect.
So, when should you get tested? If you never develop any symptoms (asymptomatic), I recommend getting tested around 7 days after exposure. By this point, you should have enough viral particles for the test to be accurate, but nothing is a guarantee. What if you have symptoms? The best timing for a COVID test is approximately 3-5 days after your symptoms start, not from the date of exposure. By this time, the viral load should be high enough to make your results more reliable. Most people start symptoms within 3-5 days of exposure, so you are really getting tested around the same 7-day timeframe as asymptomatic people if you wait 3-5 days after your symptoms start.
Be cautious when considering a COVID negative as a true negative. Nothing is a guarantee except for a guaranteed positive result. We know so little about this virus. Our detection methods are not accurate yet.
Alternative Methods for Confirming COVID-19
- Elevated ferritin levels on lab-work
- Negative flu swab with COVID-like symptoms
- Signs and symptoms of coronavirus
Clinically, patients who later test positive for coronavirus present with elevated ferritin lab levels from blood work. The results for a nasal swab can take days to result; therefore, many hospitals are instituting COVID-19 precautions on patients who present with s/sx resembling the virus and have elevated ferritin levels. This is not an option at home, but just a fun fact of the day 🤪!
What can you do at home? Get a flu swab with your COVID test. Due to the limited accuracy of testing, many physicians are testing patients who present with flu-like or corona-like symptoms with a flu swab to rule out this option. If a patient tests negative for flu, but they have COVID symptoms, healthcare providers are assuming it is Coronavirus.
How Long Should You Quarantine
If your flu swab is negative, despite not having a positive corona swab, please quarantine yourself appropriately (10 days from the peak of your symptoms as of January 2021). If your symptoms resemble coronavirus, even without any testing, I recommend quarantining yourself for 10 days from the peak of symptoms as well, helping to slow the spread. When is the peak of your symptoms? The day where your symptoms are the worst.
Signs and Symptoms of Corona Virus
The symptoms of coronavirus may not present until 14 days after you are first exposed with the virus, but most people begin having symptoms within 3-5 days after exposure.
MOST COMMON S/SX
- Dry cough
- Shortness of breath
OTHER COMMON SYMPTOMS
- Sore throat
- Body aches
- Joint pain
WEIRD COVID SYMPTOMS
- Loss of taste and smell
- Facial swelling … this was my 1st COVID symptom, weird
- Rash and hives
- COVID toes
People are losing their taste and smell, developing rashes, COVID toes, and facial swelling with this virus. Weird!
What are COVID toes? The toes swell and become discolored (red, purple, and some people even have blue toes 😱) The rash can develop into blisters. Some people struggle with the rash and discomfort for 1-2 weeks, while others progress for over a month+. The best way to treat them has been with over the counter (OTC) hydrocortisone cream and Benadryl. Another OTC medication to add to the mix would be Pepcid. ALL 3 of these medications are available OTC and help decrease the histamine response contributing to the response