COVID-19 Interest Group
April 18 2020
A bit of good news: high seroprevalence found in Santa Clara
Conclusions “The population prevalence of SARS-CoV-2 antibodies in Santa Clara County implies that the infection is much more widespread than indicated by the number of confirmed cases.Population prevalence estimates can now be used to calibrate epidemic and mortality projections."
Analysis from Arlin:
In this study, the number of random antibody tests were 3,330. Between 2.5 and 4.2% had antibodies for Covid19. In Santa Clara Co with a population of 1.9 million, this means 49,000 - 82,000 people had the Covid-19 virus by April 4. Also on that date, Santa Clara Co reported 1,148 confirmed cases. If 49,000 people are seropositive then that's 39 times the published number of confirmed cases. At 82,000 it's 71 times with a midpoint of 55x.
In a similar analysis, Alameda and Contra Costa had 1709 confirmed cases yesterday. At 55 times that would suggest 94,000 cases or ~3.5% in the 2.8 miilion A&CC population. The really good news is A &CC had a total of 59 deaths, so the mortality rate is only 0.063%! About the same as the flu! I hope this study holds up. The very best news so far...............Arlin
Pearls and pitfalls with Covid-19, a clinical peek..—Pate Thomson
Anosmia and Dysgeusia mean loss of smell and altered taste respectively. These are observed early symptom in some patients with covid-19 infections and these symptoms are a reason to test for the virus. Loss of smell and taste often go together and either would be very unusual with influenza. Otherwise these two viral infections are hard to differentiate by symptoms alone.
In Wuhan China it was noted that there was a high incidence of Covid 19 cases among ENT doctors. It is thought that infected patients with loss of smell would go see the ENT specialist and in the process transmit the Covid-19 virus to the health care provider. Why differentiate these illnesses? Because the covid-19 appears more dangerous and there are antiviral treatments effective for influenza but not yet for Covid-19.
Hypertensionis one of the most common medical problems treated by physicians and among the most common drugs used to treat this problem are ace inhibitors (ending with a pril as in lisinopril) or angiotensin receptor blockers (ARBs often ending with an artan as in Losartin). In the laboratory these drugs appear to increase the number of ACE2 receptors in respiratory cells. There was concern expressed at one point that this might increase the risk of infection with the virus because the spike on the virus finds the ACE 2 receptor and there may be more cell receptors “in waiting”, just looking for a corona virus. There has been no clinical evidence that this matters according to the American Heart Association, the American College of Cardiology and the Heart failure Society of America who have weighed in on this question. As of now, the recommendation is that patients should not stop taking these important drugs because of concern that the drugs might worsen the covid-19 syndrome.
A warning that NSAID drugs like Ibuprofen and Naprosyn could worsen the covid-19 infection was put out originally by French Health officials. The clinical evidence that this is true has not been substantiated and the warning has been withdrawn. The WHO also retracted this warning about using these drugs in Covid-19 patients.
The SARS-coV 2 virus does attack respiratory cells in upper airway passages and deep in the lung as well. The ACE2 receptor exists on these cells but it also exists in other cells in the body. The Heart, Kidney and GI tract cells are susceptible once the virus circulates. In the heart, the virus may enter the heart cells and cause inflammation resulting in myocarditis. The result may be a weakening of the hearts contractions which may result in a back-up of fluid in the lungs. Fluid in the lung caused by a failing heart may be difficult to distinguish from the fluid caused by direct inflammation within the lung triggered by the virus. It is often easier to remove the fluid if the cause is heart failure. Treatment that resolves heart failure may result in significant improvement of lung function and improved oxygenation. As with other causes of myocarditis, heart function can recover.
President Trump, In speaking about Hydroxychloroquine said, “Use it! What have you got to lose?” He touted its use with azythromycin based on a small uncontrolled study from China with equivocal results. Both of these drugs prolong the time it takes for the heart to recover (repolarize) after each beat. If the cells are not fully repolarized, the conduction of the next electrical impulse, may then be slowed and non-uniform, making the heart susceptible to serious and potentially fatal arrhythmias. A healthy heart resists serious arrhythmias, but a heart with myocarditis is susceptible. The EKG shows the medication effect as “prolongation of the QT interval”. It can be easily recognized and may be an ominous sign. So, exposing these patient to drugs with this known effect can be dangerous. Clinical studies look carefully at these and other potential adverse effects. The process is deliberate and takes time but leads to more informed decisions based on understanding the risk of a given treatment vs the benefit. Understanding both sides of this risk/benefit equation helps the doctors make better treatment decisions. The right decisions, based on real evidence can be life-saving. The wrong decisions---------? You be the judge.
Finally. a word about what we are witnessing. This is a new disease, a novel corona virus. This is a “study in progress”. We learn as we go. This is true for the health providers, the politicians, the public health officials, and all of us. In evaluating a case, when should we wait and when should we act? When should we hospitalize, move to the ICU, intubate, and resuscitate? Is there a better ventilation protocol tailored to the pulmonary effects of covid-19? Can we manage the immune response when it is excessive? What is the survival rate after intubation and what is life like once the critical illness subsides? How full a recovery can we expect? How long will it take? Will there be a treatment that proves effective? The answers will come from the experience that is being gained and the research being done and we are still in the rapid learning phase.
Until I better understand many of these elements, I will delay my appointment for an across the chest DNR*tattoo. And yes, an effective treatment or vaccine would delay that appointment even further.
*DNR = Do Not Resuscitate