Boreal B[l]og

The other day, a woman called in to Doctor Radio wondering when there was going to be a cure for Covid-19.  Her voice was peremptory, as if this were something we should all be expecting by now.  Americans are impatient, and while I am impatient, I have inhaled a dose of reality.  I know there are many drug trials, at least a dozen, with results due anywhere from next week to late September. That’s good. What isn’t so good is that if we had any trial stopping event—like polio vaccine, which was so powerful the drug trial was halted and the vaccine being given—we might know that by now. Something that pulls someone off a ventilator overnight, or ECMO, or empties an ICU is a big deal, and I haven’t heard of that yet.  I don’t expect to.  

But, we have something now. One Remdesiver trial showed the time for half the patients to recover was 11 days with the drug and 15 days without. The death rate was 8% in the control group vs. 11.6% in the treated group.  That is a 31% difference with a p-value of 0.059. The time to recover was significantly shorter; the death rate statistically not significant (want p-value under 0.05, which is the probability if chance were operating and nothing else, we could have seen this result or one more striking), but with a larger study, I suspect we would see a value under 0.05, which is an artificial construct but generally used.  Study two compared length of time efficacy; 5 days’ treatment is as good as 10 days, good news. 

From Oxford, a genetically modified MERS virus vaccine stopped Covid in macaques, a control group of whom did not survive similar doses of the virus without the vaccine. This study needs to be watched. 

But for the moment, let’s look at reality: how quickly we are going to return to whatever will be normal.  And those last four words to me are key. Sports, concerts, flying, cruise ships, restaurants, road trips, and schools aren’t going to be normal for some time, in my view, a lot longer time than many think. I have cancelled two trips this spring; I don’t expect to canoe in September, and I am not expecting to see the eclipse in December. 

Certainly not on a cruise ship.

Some wonder whether it is worth getting the virus and getting it over with.  Given the number of anecdotal cases of young and middle aged people having severe disease, I don’t think that is a wise choice, especially if one has diabetes, is obese or smokes, which are not rare in society today.  I correspond with people overseas, and one in Asia told me the whole family just got clinical Covid.  Two have anosmia, mild in the scheme of life, but people complain bitterly about it.

There are additional issues with the virus either causing a coagulopathy, where the blood doesn’t clot, or attacks the blood vessels directly.  Coronavirus myocardial damage is known; coronavirus encephalopathy and involvement of the thalamus in the brain is known, and the virus been found in the kidneys.  One third on ventilators have significant kidney disease. That should bother anyone.  I sure don’t want that at my age.

We also don’t know whether there will be after effects of pulmonary scarring, congestive heart failure, or chronic renal failure. Again, I don’t want to get this virus. 

I look at a lot of numbers and have noted from the beginning that Washington State never had a big problem after the initial attack in the nursing homes.  I expected California to explode with cases like New York, but it didn’t. Florida had people on beaches, and it had cases, but not like New York’s. I have wondered whether the population density of susceptible people mattered, and I think it does. The media does mention that “cases are rising xx per cent,” but they are rising from a smaller number.  What is clear is the numbers of cases in the mid-continent haven’t yet started to fall, whereas they have on the east and west coasts.  That concerns me, but to say the numbers are rising at 10% a day means a doubling time of 7 days, and NYC started with doubling at 3 days and continued that way for awhile.  Oregon is going to allow elective surgery.  That makes sense, because elective surgery is often biopsies and fixing things that we all have come to expect with surgery.  I think social distancing worked; we need to remember that there is a two week delay when people start moving about before we will know if there are new infections.

For those who are saying we never had to do anything, that this virus wasn’t all that bad, keep in mind that the purpose of public health workers is to prevent things. We don’t have many cases of measles; if people vaccinated, we wouldn’t have any.  It’s not that measles is gone; it just doesn’t have a home here. We social distanced and we cut the number of Covid-19 cases.  Not enough, and the numbers are well past the number of deaths from influenza that people quote every year.  I suspect they will be more than 100,000, the low end of the original estimate. We are already 11,000 over the estimate for 1 May that I read two weeks ago.

The other issue is testing, an important catchword, and we need to also know how good tests are,  Recently several were checked; three were good.  It turns out, (proof below),  a test that is 90% specific (one has the disease, test is positive) and 95% sensitive (one doesn’t have the disease, test is negative) and the disease is relatively uncommon (5% of people), a positive test has a 50% chance of being false positive.  It is the difference between “if I have the disease what is my test?” and “I test positive, do I have the disease?”  The more common the disease in the underlying population, the more likely a positive test is true.  It’s why public health people did not require AIDS testing for wedding licenses. The disease was uncommon enough that a third of the positives were true and the other false. 

5% prevalence of disease

This is sensitivity of 90% (45/50) and specificity of 95% (902.5/950).  Positive test has (45/92.5) or 49% chance of being a true positive, even when the specificity and sensitivity are both 90% or more.

Same with a 20% prevalence in the community would make false positives only 18%.

So, I wear my mask, take my walks, and wait. 

Maybe next year we will do a lot more, but not soon.  We don’t yet know for sure whether people are immune to the virus after having had it or can get it again. There is a bit of national denial in thinking that sports will start soon. They won’t until or unless there is a vaccine or an anti-viral better than Remdesivir. Additionally, we don’t know what it will take to get a vaccine, or whether a vaccine will even be effective, let alone for how long and what side effects are present. People want something, but vaccines can backfire and overstimulate the immune system, which is a huge problem with this virus.  Indeed, many medicines are in trials to see if they can turn down the immune system.  In the meantime, beware of those who are pushing strengthening our immune systems.  Stay in good health and let your immune system take care of you.

We are finally doing random sampling in various cities to get a sense of how many asymptomatic infections are present.  The evidence we had from China was that few were asymptomatic.  That is not true. We need more information about relative risk, not that 2/3s of the deaths are over 70 but what the risk of a 70 year-old or more, without chronic disease, surviving. That’s a different question.  We need to give the risk to people in various decades of life with and without chronic disease as to what their risks are—to be asymptomatic, to avoid hospitalization, to avoid ventilators, and to avoid death.  

If public health professionals are doing their job, people will complain that they were too strict. 

It’s nice to be still alive to complain.

This entry was posted on April 29, 2020 at 18:46 and is filed under Medicine. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.