Asymptomatic Risk: Study Finds Covid Damage & Dubious Immunity

In a medical paper just published in Nature, Chinese researchers revealed the results of a study on asymptomatic and mildly symptomatic Covid-19 patients. Their findings cast significant doubt about natural immunity to the novel coronavirus and our ability to achieve herd immunity, as well raise alarming concerns about the material health risks posed to even asymptomatic carriers of the disease.

The peer-reviewed research, published on June 18th, finds that “IgG levels and neutralizing antibodies in a high proportion of individuals who recovered from SARS-CoV-2 infection start to decrease within 2-3 months after infection”—especially for those patients who are asymptomatic.

Asymptomatic SARS-CoV-2 Infections: Damage on the Clinical Side & Nothing but Doubts on the Immunological Side

However, the study revealed a host of other significant insights into the pathogenicity and virulence of the Covid-19 virus as well—insights everyone (even the young and otherwise healthy) should pay close attention to.

Specifically, the findings of the study reveal five key points:

  • Antibody levels were significantly lower in asymptomatic carriers
  • Antibody levels dropped off far more quickly for asymptomatic carriers—40 percent had no detectable antibodies eight weeks after recovery
  • Even 13 percent of symptomatic patients had no detectable antibodies eight weeks after recovery
  • Asymptomatic carriers shed the virus (and may be contagious) five days longer than symptomatic patients—19 days versus 14 days
  • A high proportion of asymptomatic carriers showed lung abnormalities

There’s a lot to unpack from this highly informative (albeit small) study… so let’s breakdown these key points and see what it all means for us…

Background on the Chinese Coronavirus Study

The study by Chinese researchers examined a group of 178 individuals—all with confirmed Covid-19 infections—during and after their infections.

Of these, 37 (20.8%) were asymptomatic (and remained so throughout the entire study). Furthermore, of the asymptomatic patients, the mean age was 41 (8-75) and 22 were female. What’s interesting to note is that this study covered a large distribution of ages—it was not concentrated on older folks.

It is important to note that the symptomatic patients were suffering from mild symptoms—no severe or critical patients were included (nor skewed the results).

Asymptomatic Covid-19 Carriers Show Low Levels of Antibodies

The first significant takeaway from the study was that asymptomatic carriers show a significantly lower level of neutralizing antibodies (IgG).

Specifically, the study found “The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6–10.7) were significantly lower (P = 0.005) relative to the symptomatic group.”

This is highly statistically significant and corroborates a growing mountain of research indicating the level of initial antibody immunity is directly correlated to the severity of the infection—meaning, asymptomatic infections provide individuals with little to no initial immunity to the virus.

Furthermore, the study found 19% of asymptomatic and 16% of symptomatic patients has no detectable neutralizing antibodies (IgG) during the acute phase.

Percentage of Covid-19 Patients with Detectable Neutralizing Antibodies (IgG) during the Acute and Convalescent Pases.

This differs from another recently published (non-peer-reviewed pre-print) study by researchers from St. George’s University of London that found that up to 8% of patients (symptomatic) failed to manifest detectable antibodies to the virus. However, the data beyond 30-days in the study was very limited and the margin of error indicated the same overall decline in antibodies found in the Chinese study.

Short-term Degradation of Covid-19 Immunity

Another preprint study out of The Netherlands took a different approach, examining individuals over a 35-year span (2,473 follow up person-months) in an effort to determine the degree of immunity achieved against the four seasonal human coronaviruses (HCoV-NL63, HCoV-229E, HCoV-OC43, and HCoV-HKU1).

While Covid-19 is a unique virus, it is reasonable to presume that we can gain some general insights by examining other common virus strains in the same family.

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The researchers found that “Reinfections occurred frequently at 12 months post-infection and there was for each virus a substantial reduction in antibody levels as soon as 6 months post-infection.”

Specifically, they found that the majority of patients lost 50% of their antibodies within 6 months and 75% within a year.

Percentage of Covid-19 Patients with Depleted Immunity (Levels of Antibodies) Over Time

So, for those trying to get the virus so they can “go ahead and get it over with,” there actions may prove to be the proverbial equivalent of “pissing into the wind.” There is no empirical evidence to support the idea that they won’t (or can’t) get it again.

In fact, based on the evidence that as many as 70% of recovered patients can lose 50% of their antibodies within six months (and most asymptomatic patients start with very low levels), we may see a wave of re-infections beginning in November and December (coinciding with the heart of the flu season) for millions of Americans who contracted Covid-19 prior to the end of June.

(And we have no idea if a second infection will be worse???)

Furthermore, as we shall see later, they are taking on a significant amount of risk—risk in the form of chronic (potentially lifelong and lifestyle altering) health consequences. In other words, they are engaging in asymmetrical risk of the worst kind—where the risks far outweigh the reward (aka negative skew).

Covid-19 Poses an Asymmetrical Risk (with Negative Skew)--a Bad Risk-Reward Equation for Individuals

Asymptomatic Covid-19 Carriers Lose Immunity Quickly

Next, the researchers note that all patients infected with the novel coronavirus—but especially asymptomatic carriers—lose antibody immunity relatively quickly.

Specifically, the study found that by 8-weeks following discharge, the IgG levels in 93% of asymptomatic patients declined (by a median of 71%) and 97% of symptomatic patients declined (by a median of 76%).

The Decline in Antibody (IgG) Levels for both Asymptomatic and Symptomatic Patients from the Acute Phase to the Convalescent Phase (as Measured at 8 Weeks)

In fact, the research showed that “by eight weeks post-recovery, 40.0% (12/30) of asymptomatic individuals, but only 12.9% (4/31) of symptomatic individuals, became seronegative for IgG.”

Dr. Samir Gupta, a clinician-scientist at St. Michael’s Hospital in Toronto and assistant professor of medicine at the University of Toronto, noted, “What was ‘a little bit surprising’ was the fact that 40 per cent of people with asymptomatic infections had no detectable antibodies at all.”

Tania Watts, a professor of immunology at the University of Toronto, expressed concern about the implications, stating, “This suggests that natural infection may not give long-lasting immunity, which is what people have been worried about,” adding, “The low and short-lived levels of antibodies in asymptomatic infections in this study suggest we can’t rely on herd immunity being induced for long enough a period of time to have an impact.”

Again, this study—albeit a small sample size—found that 40% of asymptomatic and even 13% of symptomatic patients had no (that’s ZERO) detectable antibodies (IgG) within just eight weeks of “recovery.”

Asymptomatic Carriers Found to Shed Covid-19 Virus Longer

The fourth key takeaway from the study was that the duration of the illness and, therefore, viral shedding, was significantly longer for asymptomatic carriers.

Specifically, regarding the asymptomatic carriers, researchers found that “the median duration of viral shedding, defined as the interval from the first to last positive nasopharyngeal swab, in the asymptomatic individuals was 19 days (IQR, 15–26 days),” adding, “The shortest observed duration of viral shedding was 6 days, whereas the longest was 45 days.”

On the other hand, for the symptomatic patients, “The median duration of viral shedding was 14 days (IQR, 9–22 days) in patients with mild symptoms.”

In other words, “The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028).”

Duration of Viral Shedding in Asymptomatic and Symptomatic Covid-19 Patients

Regarding this important revelation, Watts stated that “she thinks the finding in this study that people without symptoms shed the virus longer than people with symptoms is ‘shocking’ and suggests we need to worry about transmission from asymptomatic people.”

To be honest, I don’t understand why Watts would find this “shocking,” given that we have known about asymptomatic spread and super carriers since at least January; however, this study does lend yet more support to the virtually undeniable assertion that masks matter—both for the one wearing it (to reduce any initial viral loads received) and, even more importantly (given the nature of asymptomatic transmission), for those whom that person come into contact with.

This is NOT a “my body, my decision” proposition. The fact is that one has no way to “know” if they are infected without continuous testing—meaning, they can quite easily and unknowingly infect others. Thus, this debate involves everyone’s body and should, therefore, be a corporate (societal) decision.

It is important to note, as did the researchers in this study, that “detection of viral RNA does not necessarily mean that infectious virus is present in respiratory specimens, and caution is required when applying virus shedding duration that was calculated based on RT–PCR to assess infection potential.”

However, given the absence of any data to suggest such viral shedding is not infectious, we would all be wise to err on the side of caution and proceed as though it is.

Asymptomatic Coronavirus Patients Show Lung Damage

Finally, and we would argue most importantly, this study once again demonstrated that asymptomatic does not mean folks are not negatively impacted by damage to their body.

The researches note that, upon hospitalization (for observation), “Chest computed tomography (CT) scans showed focal ground-glass opacities in 11 asymptomatic individuals (11/37, 29.7%) and stripe shadows and/or diffuse consolidation in ten individuals (10/37, 27.0%).”

Asymptomatic Coronavirus Patients Show Lung Abnormalities on Chest CT scans--Including Ground-Glass Opacities and Stripes

Furthermore, within 5 days of observation, “five more patients developed focal ground-glass opacities or stripe shadows on chest CT.”

In fact, the reported that “abnormal radiological findings confined to one lung were identified in 66.7% (14/21) of the asymptomatic individuals, whereas 33.3% (7/21) had abnormalities in both lungs.”

This should be alarming for all those who think—because they are likely to be asymptomatic—this virus is “no big deal.”

The facts—not just from this study but from literally hundreds of studies conducted from the early days of the pandemic to the emerging research today—unequivocally indicate that Covid-19 results in some degree of damage to a very large proportion of asymptomatic patients. That damage might (or might not) have a material impact on one’s quality of life now… but it is highly likely that it will later in life.

Again, 70 percent of asymptomatic patients—those manifesting no (zero) outward symptoms—had lung abnormalities detectable in X-rays at some point during infection—mostly spots called “ground-glass opacities,” which can indicate inflammation or other signs of disease.

That’s significant… and that should cause one to quickly realize they do not want to get this virus if possible.

To learn more about the chronic health issues that so-called “recovered” coronavirus patients are struggling with, we highly encourage you to read our two-part series: Recovered Doesn’t Mean Healthy: The Untold Truth about Covid-19 (Part I) and Chronic Covid-19 Syndrome: Long-Tail Recovery Risks Emerge (Part II).

A Silver Lining: Other Research Still Extends Hope for Potential (Alternate) Immunity

The only silver lining is that neutralizing antibodies are not the only that our bodies fight an infection. Our immunological response is complicated, and also includes the work done by T-cells.

While antibodies target the virus directly, T-cells destroy our own cells that have become infected by them. These T-cells “remember” foreign invaders and trigger a response when they see them again.

A small study out of Sweden has recently found that for every person testing positive for antibodies (IgG), two were found to have specific T-cells which identify and destroy infected cells (aka T-cell-mediated immunity).

Mitch Leslie, writing for Science Magazine, notes that two earlier studies “reveal infected people harbor T cells that target the virus—and may help them recover.” However, she adds, “The studies don’t clarify whether people who clear a SARS-CoV-2 infection can ward off the virus in the future.”

This means that it’s possible that infected patients could still have a form of more long-lasting immunity.

However, just how effective and how long that immunity may be remains to be determined. Furthermore, the source of these “killer” T-cells is unknown—meaning, they could have been acquired from previous exposure to other coronavirus strains. If that’s the case, research has raised concerns as to whether general (broad) defenses will be effective against SARS-CoV-2.

For example, while in theory, “Antibodies induced by coronavirus infections may have broad coronavirus-recognizing characteristics,” researchers studying other strains of coronaviruses (both in the genus Alphacoronavirus and Betacoronavirus) found that “it does not seem that broadly recognizing antibodies are broadly protective as HCoV-NL63, HCoV-229E, and HCoVOC43 infections occur in the presence of the broadly recognizing antibodies.”

It is worth noting that Covid-19 has shown a propensity for directly attacking T-cells in our body. This may pose an additional weakness for those that may develop a weakened immune system in the future due to a plethora of reasons.

Because natural immunity is so questionable at this point, it points to the ultimate need of an effective vaccine.

As Akiko Iwasaki, a viral immunologist at Yale University, notes, “These reports highlight the need to develop strong vaccines, because immunity that develops naturally during infection is suboptimal and short-lived in most people. We cannot rely on natural infection to achieve herd immunity.”

However, Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, has pointed out these different immunological responses and warns that people do not have “a uniformly robust antibody response,” which may make it difficult to develop a vaccine that works equally well for all people.

Finally, this reality, as Emily Chung, Christine Birak, and Marcy Cuttler, writing for CBC News, aptly note, “Throws cold water on the idea of controversial ‘immunity passports,’ the idea of allowing more social interactions, such as work, travel and mass gatherings, for people who have previously been infected and therefore are immune and can’t spread the virus—which would be based on serological testing.”

That serological testing only identifies the presence of antibodies—not T-cells with the memory to target host cells infected by the novel coronavirus.

Echoing the doubts about achieving natural herd immunity, the researchers from the earlier noted coronavirus study concluded:

“Our study also shows that herd immunity may be challenging due to rapid loss of protective immunity… As protective immunity may be lost by 6 months post infection, the prospect of reaching functional herd immunity by natural infection seems very unlikely.”

For more on the question of achieving “herd immunity,” we recommend reading our article Study Finds High Initial Covid-19 Infection Rate: Herd Immunity Close?


As we have shown, the Chinese researchers have advanced five critical points regarding our understanding of the novel coronavirus:

  • Antibody levels were significantly lower in asymptomatic carriers
  • Antibody levels dropped off far more quickly for asymptomatic carriers—40 percent had no detectable antibodies eight weeks after recovery
  • Even 13 percent of symptomatic patients had no detectable antibodies eight weeks after recovery
  • Asymptomatic carriers shed the virus (and may be contagious) five days longer than symptomatic patients—19 days versus 14 days
  • A high proportion of asymptomatic carriers showed lung abnormalities

Not only did the study find that 40% of asymptomatic carriers of Covid-19 have no detectable antibodies (IgG) after just eight weeksneither did 13% of their symptomatic patients!

This supports the hypothesis that any meaningful immunity via antibodies is highly doubtful—casting doubt on the idea of ever achieving natural herd immunity.

Most importantly, the study highlighted that a large percentage of entirely asymptomatic patients were found to have sustained damage to their lungs. Given that this was the only clinical observations conducted, it is highly likely that this damage extended to other areas of their bodies—especially given the wide-range of areas targeted by Covid-19.

Specifically, the study shockingly—and I mean it should shock any and everyone who has minimized or downplayed the risk of the virus—found that 70% of the asymptomatic patients showed focal ground-glass opacities, stripe shadows, and/or diffuse consolidationin one or both lungs!

In conclusion, we encourage you to wear a mask and practice social distancing—especially given that this study confirms that asymptomatic carriers (individuals that no one—including themselves—can identify as infected) appear to shed the virus even longer than those presenting symptomsnearly three weeks from infection. (Which, incidentally, may help to explain why most super spreaders have turned out to be asymptomatic carriers.)

While we shouldn’t fear the virus, we should maintain a healthy respect for it—and take reasonable and prudent actions to avoid getting it. You really don’t want to get this thing… as more and more “recovered” coronavirus patients are sadly discovering.

Finally, while we can (and should) hope for a quick and effective vaccine, the reality is that hopes are fading for achieving any meaningful degree of immunity without it. This means—especially as we move into the fall flu season—that things could continue to deteriorate and, ultimately, get much worse before they get better.

As such, it is absolutely essential that you continue prepping! We need to continue to skew the risk-reward balance in our favor as much as possible.

Be smart and rational—not irrationally, emotional, and ideological. Take the steps you can to put yourself and your family in the most defensible position possible. If things blow over and we somehow manage to avoid catastrophe… well, no harm, no foul! You’ll just be that much more prepared for the next crisis.

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As always, hope for the best, prepare for the worst, and—in all things—pray!

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Doug is a passionate servant of Christ and holds an MBA, BBA (Summa Cum Laude), and AAcc from Liberty University, as well as an additional two years of study at Bible college. He has over 20-years of corporate finance, accounting, and operations management experience—spanning the public, private and nonprofit sectors. He is proud to have served his country as a member of the 82nd Airborne Division and his local communities as a firefighter/EMT and reserve peace officer—experience that has provided him with a unique skill-set when it comes to emergency medicine, firearms, crisis management, and wilderness survival. Doug enjoys playing the drums, prepping, and spending time with family—especially in the Outer Banks of NC.