Archive for category COVID-19
This post is about a simple idea that came to us from Reverend Thomas Bayes (b. 1701) who studied statistics (now called Bayesian Method) . Here is the basic idea:
If a disease is very common, the test for it can be very simple.
If a disease is very uncommon, the test for it needs to be very accurate.
In regard to the 2020 COVID-19 pandemic in the U.S., the virus is very common. So, at this time the easiest and most accurate test is a simple questionnaire. In this questionnaire if you have two or three of the symptoms then you likely have COVID-19. If you have been in contact with someone with known COVID-19 and have any symptoms, then you likely have COVID-19. Is testing a symptomatic person absolutely needed? No. But, that’s not the end of the story, see the connected issues below.
☐ Fever or chills
☐ Shortness of breath or difficulty breathing
☐ Muscle or body aches
☐ New loss of taste or smell
☐ Sore throat
☐ Congestion or runny nose
☐ Nausea or vomiting
So, if this simple check list is so great, why do some people need the nasal or oral swab testing (PCR viral test)? Because the virus sometimes causes no symptoms — early or late in the disease and sometimes never. Note that the check list did not have “
☐ No Symptoms” as a selection. That makes sense, there is no way a person would think they are sick if they feel fine — yet they may be spreading virus to many other people.
The concern about “silent spreaders” is a huge problem. Once a person is known to have COVID-19 (diagnosed or suspected) then that person needs immediate quarantine for 14 days and must get in contact with the health department to start tracking down contacts that MAY OR MAY NOT have symptoms. Those contacts without symptoms should have the nasal or oral PCR testing if available. As they wait for the results (which can take hours to days) they must be quarantined.
Some silent spreaders can be tough to track down: taxi drivers, doormen, receptionists, grocery clerks, and bus drivers. Essentially, people who have huge numbers of contacts that people often forget to mention. Here is a scary thought: if people around you are getting COVID-19, maybe you are the silent spreader.
The Health Department has a huge job, and they need everybody’s help. Do what they say, don’t waste their time, and become informed by reading about the disease online. The 130,000 deaths so far in the U.S. is very serious business.
Someday COVID-19 will be uncommon (that would be nice), then we will need a very accurate test for the disease. That very accurate test sadly does not exist right now (PCR currently has about 30% false negatives — meaning the test is negative, but you actually have it).
When the vaccine is available, take it ,and in the mean time, wear your mask and practice social distancing.
You will need to wear a mask outside home and avoid close contacts until two weeks after receiving a Covid-19 vaccination. That’s the simple truth.
A vast amount of information in the media currently is irrelevant, misconstrued, politically motivated or wrong.
What we know about Covid-19 in June 2020:
- It is extremely contagious and is spread person to person
- 2 – 3 percent of people who catch the virus die
- It is spread by inhaling small particles in the air and to a much less amount by touching objects then touching your face.
- Masks reduce the chance of contracting or spreading the disease
- N95 masks are best (KN95 masks are adequate)
- Two-layer cotton masks are pretty good (flannel over muslin) — try to obtain a good fit over the bridge of the nose and below the chin.
- Social distancing is very helpful, especially outdoors
- Washing hands frequently with soap and water or 60% ethyl alcohol hand jell is very helpful
- Tight spaces or large gatherings increase the spread
- The best measure of its presence is the number of people who require hospitalization (multiply by 10 to know the number of people who have the disease but did not require hospitalization.
- If you are in a location where the disease is active (a hot spot) and have symptoms of fever, cough, muscle aches and headache you have the disease. (i.e. “the symptoms”)
- If you have no symptoms, or minimal symptoms, you might still have the disease (this is a real nightmare for tracking the disease and why virus testing is so important).
- If you have active Covid-19 disease, a PCR throat swab will be wrong 30% of the time. And, two negative tests will be wrong 9% of the time. Don’t endanger your loved ones based on the test — if you were exposed, stay in isolation for 2 weeks.
- You can be 95% sure a positive PCR throat swab test is accurate if you also have the symptoms.
- Tiny mutations happen to the DNA inside Covid-19 which help researchers trace the path of the virus through the population. The mutations are not changing the infectivity or lethality of the disease, so far. If a major mutation happens it is likely to make the virus less powerful (nice thought, but it has not happened).
- Surviving the disease means your body made antibodies to fight the virus. Some studies show marked reduction in natural antibody production a couple of months later. Hopefully, vaccinations will do better.
- Antibody level tests done several weeks after infection (at least 2 weeks) are not very accurate as of July 2020.
- Infected persons are usually non-infectious 10 days after symptoms subside. Unfortunately, elderly persons may be infectious longer so in that group two negative tests a day apart are advised before ending isolation.
- Current projections suggest vaccinations will be available for healthcare workers in December 2020, for high risk individuals in January 2021 and for the general public (in the US) later in 2021.
- The world population will need 7 billion vaccinations
Nasal swab technique
Time and time again, photos in the media show patients having their noses swabbed to obtain a sample for virus testing — usually incorrectly. The swab is inserted perpendicular to the face, into a nostril, to a depth equal to the distance from the nostril to the ear canal. See article in the New England Journal of Medicine.
Why does it matter? Because an incorrect swab placement will fail to obtain an adequate sample and lower the chance of an accurate test (and hurt like crazy). Many negative tests in people with Covid-19 are due to poor technique done by poorly trained health workers.
According to environmental engineers at Perdue University, cruise ships use 50 percent recirculated air from other cabins and other rooms to ventilate passenger and crew cabins. Since Covid-19 is carried in the air, viral filters (not just dust filters) are needed. Unfortunately, ships so far don’t have them. Caveat emptor.