There are three
types of COVID-19 tests: molecular, antigen and antibody. Molecular and
antigen tests detect active infections, whereas the antibody test will
tell you if you’ve developed antibodies in response to a previous
SARS-CoV-2 infection
There are seven
different coronaviruses known to cause respiratory illness in humans.
The antibodies created by these different coronaviruses appear very
similar, and recovering from the common cold may trigger a positive
antibody test for COVID-19, even if you were never infected with
SARS-CoV-2 specifically
While experts
at the Mayo Clinic claim cross-reactive antibody tests were an early
problem that has been corrected and eliminated, the CDC has not
confirmed this
A Singaporean
study found common colds caused by the betacoronaviruses OC43 and HKU1
appear to make you more resistant to SARS-CoV-2 infection, and that the
resulting immunity might last as long as 17 years
Other studies suggest immunity after COVID-19 infection may only last between two and 12 months
Right now, there are three types of COVID-19 tests:1
Molecular — Also known as a PCR (polymerase chain reaction) test,
this test detects whether genetic material of the virus is present in
the sample collected from your throat or sputum (the back of your
sinuses)
Antigen — This test, sometimes referred to as "rapid test," detects viral proteins
Antibody — Also known as a serology test, it detects the presence of antibodies in your blood
The first two, molecular and antigen, are so-called "viral tests"
that detect active infections, whereas the antibody test will tell you
if you've developed antibodies in response to a previous coronavirus
infection. It typically takes your body one to three weeks after an
infection clears to start making antibodies against the virus in
question.
Common Cold Can Trigger Positive COVID-19 Antibody Test
Each of these COVID-19 tests have their issues and controversies.
The problem with antibody testing is that there are seven different
coronaviruses known to cause respiratory illness in humans.2 Four of them cause symptoms associated with the common cold:
229E
NL63
OC43
HKU1
In addition to the common cold, OC43 and HKU1 — two of the most commonly encountered betacoronaviruses3
— are also known to cause bronchitis, acute exacerbation of chronic
obstructive pulmonary disease and pneumonia in all age groups.4 The other three human coronaviruses — which are capable of causing more serious respiratory illness — are:
SARS-CoV
MERS-CoV
SARS-CoV-2
The tricky part is that the antibodies created by these different
coronaviruses appear very similar, and the U.S. Centers for Disease
Control and Prevention admits recovering from the common cold can
trigger a positive antibody test for COVID-19, even if you were never
infected with SARS-CoV-2 specifically.
As explained on the CDC's "Test for Past Infection" web page:5
"Antibody tests check your blood by looking for antibodies, which
may tell you if you had a past infection with the virus that causes
COVID-19. Antibodies are proteins that help fight off infections and
can provide protection against getting that disease again (immunity).
Antibodies are disease specific …
A positive test result shows you may have antibodies from an
infection with the virus that causes COVID-19. However, there is a
chance a positive result means that you have antibodies from an
infection with a virus from the same family of viruses (called
coronaviruses), such as the one that causes the common cold."
Unclear if Cross-Reactive Antibody Tests Are Still Being Used
In a July 10, 2020, interview with KTTC news, Mayo Clinic chair of clinical microbiology, Dr. Bobbi Pritt, said:6
"Early on we had labs using tests that have not received that [U.S.
Food and Drug Administration] review and some of those tests … may
have given you a false positive and detected the normal coronavirus
that circulates and causes the common cold. I would say the
vast majority have been extensively tested to show that they do not
cross react and give you false positives due to the common cold
[anymore]."
While experts at the Mayo Clinic claim these cross-reactive antibody
tests were an early problem that has since been corrected and
eliminated, the CDC does not confirm or deny the accuracy of this
statement on its "Test for Past Infection" web page.7
So, it's unclear whether the antibody tests manufactured and used
today are still capable of delivering a positive result if you were
recently exposed and recovered from the common cold virus.
Back on April 29, 2020, infectious disease specialist and CNN
medical analyst Dr. Kent Sepkowitz noted that "deciphering between the
common cold antibody and the COVID-19 antibody is a real challenge
scientifically,"8 but that doesn't mean it cannot or hasn't been done.
On a side note, labs are now reporting a shortage of chemicals and
disposable pipette tips required to perform COVID-19 tests, which means
longer wait times — again. As Scott Shone, director of the North
Carolina State Laboratory of Public Health, told The New York Times,9,10
July 23, 2020, “It’s like Groundhog Day. I feel like I lived this day
four or five months ago,” referring back to the early days of the
pandemic when test supplies were in short supply.
Some Coronaviruses May Impart Resilience Against COVID-19
While the CDC warns it's still uncertain whether COVID-19 antibodies
prevents reinfection, or if it does, for how long, researchers in
Singapore have presented evidence11,12,13 suggesting the immunity is likely to be long-lasting.
They discovered common colds caused by the betacoronaviruses OC43
and HKU1 appear to make you more resistant to SARS-CoV-2 infection, and
that the resulting immunity might last as long as 17 years.
The authors suggest that if you've beat a common cold caused by a
OC43 or HKU1 betacoronavirus in the past, you may have a 50/50 chance
of having defensive T-cells that can recognize and help defend against
SARS-CoV-2. As reported by the Daily Mail:14
"Scientists have found evidence that some immunity may be
present for many years due to the body's 'memory' T-cells from attacks
by previous viruses with a similar genetic make-up — even among people
who have had no known exposure to Covid-19 or SARS …
Blood was taken from 24 patients who had recovered from COVID-19,
23 who had become ill from SARS and 18 who had never been exposed to
either SARS or COVID-19 …
Half of patients in the group with no exposure to either
Covid-19 or SARS possessed T-cells which showed immune response to the
animal betacoronaviruses, COVID-19 and SARS. This suggested patients'
immunity developed after exposure to common colds caused by
betacoronavirus or possibly from other as yet unknown pathogens."
According to the researchers, their findings demonstrate that:15
"Virus-specific memory T-cells induced by betacoronavirus infection
are long-lasting, which supports the notion that COVID-19 patients
would develop long-term T-cell immunity. Our findings also raise the
intriguing possibility that infection with related viruses can also
protect from or modify the pathology caused by SARS-Cov-2."
Added support for these conclusions were published May 14, 2020, in the journal Cell. This study16
found that not only did 70% of samples obtained from recovered COVID-19
patients have resistance to SARS-CoV-2 on the T-cell level but so did
40% to 60% of people who had not been exposed to the virus. According
to the authors, this suggests there's "cross-reactive T cell
recognition between circulating 'common cold' coronaviruses and
SARS-CoV-2."
Other Researchers Report Low Immunity Post-Recovery
The immunity issue isn't entirely cut and dry, though. Other
research, which looked at antibody levels in recovered COVID-19 patients
in Germany, found they lost their antibodies after two to three
months.
"Clemens Wendtner, a chief physician at the hospital, tested
COVID-19 patients for immunity after they had been treated for the
disease at the end of January 2020. The tests showed a significant
decrease in the number of antibodies," DW reported in a July 14, 2020, article.17
"Wendtner says 'neutralizing' antibodies, which stop a viral
attack, fell in four out of nine of the patients who were tested,
within two to three months. Those findings coincide with a similar
investigation done in China.
That study also found that antibodies in COVID-19 patients do
not persist in the blood. Further research is still required. But these
initial findings suggest that a second infection is possible …"
However, it is important to realize that loss of the ability to
determine antibody levels may not necessarily reflect lack of immune
protection, as there may be innate cell mediated immunity that provides
protection that is not being measured by the humoral antibody
production.
Will COVID-19 Behave Like the Common Cold?
If reinfection is possible, then COVID-19 would behave much like the
common cold and seasonal influenza, which can strike more than once —
if not in a single season, then certainly in any given year. If that's
the case, then "immunity passports" and most other COVID-19
interventions, such as school closings and business shutdowns, become
even more questionable than they already are.
If SARS-CoV-2 ends up behaving like other human coronaviruses that
cause the common cold, immunity may only last six to 12 months, a
European study18
says. Here, they did not look at SARS-CoV-2 antibodies but, rather,
antibodies against the other four coronaviruses that cause the common
cold, none of which were long-lasting. According to BGR, which reported
the findings:19
"'Frequent reinfections at 12 months post-infection and
substantial reduction in antibody levels as soon as 6 months
post-infection' were observed for those viruses.
If the novel coronavirus behaves the same way, then talk of
'immunity passports' and herd immunization is pointless. A person who
recovered from COVID-19 could get it again in six to 12 months without
another vaccine shot …
The researchers note that the human coronaviruses are 'biologically
dissimilar' and 'have little in common, apart from causing the common
cold.' But SARS-CoV-2 doesn't have to be similar to any of them to
follow the same immunity pattern."
Is Herd Immunity Against COVID-19 Possible?
The issue of reinfection also raises questions about whether herd
immunity is ever going to be possible. Studies cited by The Daily Mail20 claim herd immunity against COVID-19 could be achieved if just 10% to 43% of people develop lasting immunity.
This is a far cry from the percentages typically required for
vaccine-induced "herd immunity" (which is really a misnomer, as
vaccine-induced immunity doesn't work like natural immunity, and herd
immunity is really only achieved when enough people recover from the
illness in question). According to The Daily Mail:21
"The concept of herd immunity hinges on people only being
affected once, so that when a certain number of people have been
infected with the virus already it can't spread any more.
It remains a mystery as to whether this is the case for COVID-19
but, if it is, then herd immunity could offer some protection during a
second wave of the disease …
Researchers now say it could work to some extent if only one or
two out of 10 people have been infected naturally and become immune to
the disease … Another study has taken a similar line and suggested herd
immunity could develop at around 43 percent of the population getting
infected … Immunity among the most socially active people, scientists
say, could protect those who come into contact with fewer others."
Optimizing Vitamin D May Be Your Best Bet
Considering the many questions surrounding the possibility of
reinfection and herd immunity, I believe one of your best bets is to
address an underlying weakness that can have a significant impact on
your COVID-19 risk, namely vitamin D insufficiency.
Rather than waiting for a likely harmful vaccine, get proactive and
start optimizing your vitamin D level. You can learn more about this in
"The Most Important Paper Dr. Mercola Has Ever Written" and "How to Fix the COVID-19 Crisis in 30 Days." Also start working on reversing any underlying comorbidities such as insulin resistance and obesity.
When Should You Get Tested?
As for testing, I do not recommend getting a viral test (which
checks for active infection) unless you have COVID-19 symptoms and need
it to guide your treatment. Swabbing the back of your nasal cavity has
its risks, and can actually introduce an infection or, some speculate,
even some more nefarious agents.
Getting tested just for the heck of it doesn't really make sense.
Even if you test negative, you can get infected at any point after
leaving the test site. If you have to get tested in order to travel or
return to work, an antibody test may be more appropriate. Even if your
antibodies wane with time, you're still going to be immune for a while.
The best test are your clinical symptoms. If you have symptoms
suggestive of coronavirus infection, then my best recommendation is to
start nebulizing food grade hydrogen peroxide at 0.1% as suggested in
the video below and discussed in my article on the topic.
I would also make sure that your vitamin D levels are adequate, as discussed in my paper on the topic.
If you don't know your vitamin D level and have not been in the sun or
taken over 5,000 units of vitamin D a day, it would likely help to
take one bolus dose of 100,000 units, and make sure you are taking
plenty of magnesium, which helps convert the vitamin D to its active
immune modulating form.
Another great option that is less expensive, easier to get and likely more effective than hydroxychloroquine, would be quercetin with zinc as discussed in my recent article on the subject.
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