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October 31, 2020

Why are some people superspreaders?

The production of infectious aerosol droplets can vary widely between people. If you look at people expire in cold weather you can see that the size of their breath cloud varies considerably when exhaling. Aerosol droplets are created in the bronchioles of the lungs, the larynx, and the mouth. The shapes of the body, loud talking, and breathing fast all have a major role in spreading the droplets.

Shouting amd singing, especially in Karaoke Bars, have been a big source of superspreading events.  At least forty adults were infected on Aug. 23rd at a Karaoke Bar in Quebec City and then they passed it along to 10 family members. 


An aerosol is any particle that can be suspended in air for minutes to hours - and are usually less than 100 micrometers in size. The respiratory fluid in the lungs create a film that bursts like soap bubbles as the bronchioles and larynx expand and contract. All the aerosols and droplets are trapped in an explosive puff of gas which carries them into the air. Superspreaders produce an order of magnitude more than other people even when talking. This may be due to variations in the thickness of their respiratory fluid. This field of science is difficult but advancing rapidly during the SARS-CoV-2 epidemic. (National Geographic October 2020)

October 28, 2020

Vaccine Hesitancy

Vaccine hesitancy is defined as lack of acceptance or refusal of vaccination despite availability.  Herd immunity, which could control the pandemic, occurs when 60-70% of the population have antibodies against the virus.  Covid-19 infections have produced natural immunity in only 10 % of the US to date.

That means that we still need vaccination to achieve immunity in 60-70% of the population.  Recent surveys demonstrate that 70% of those who would accept a vaccine last spring has dropped to near 50% of people who now will be vaccinated. 

If only 50% of people will be vaccinated, and the vaccine may only be 50-60% effective, vaccination will only increase immunity to 25-30% of the US.  After digesting these numbers it becomes apparent that we will only have 10% + 30% = 40% toward herd immunity, and more people need to be willing to be vaccinated.  One of the lectures at the FDA Hearing last week presented reasons why more patients now have vaccine hesitancy.  See Below.


In a Reagan-Udall Foundation supported study, researchers discovered that there were multiple reasons for vaccine hesitancy:

1.  The speed of vaccine development raised questions about vaccine safety.

2.  There is distrust of the Government, FDA, WHO, and health-care systems.

3.  There is worry about a political and economic priority over science.

4.  Vaccines may not "work for me" - my group hasn't been included in the Clinical Trials (race, age, and comorbidities).

5.  There is fear among Blacks because of the old government Tuskegee Experiments in which black men were not treated for syphilis so the course of the disease could be studied by the government. 

Much work needs to be done to allay these fears in the next 6 months. 



October 24, 2020

When Will the First Vaccines Be Approved?

The Vaccines and Related Biologic Products Advisory Committee of the FDA (VRBPAC) Hearing: 

Members of this big committee are from academia: virologists, pediatricians, epidemiologists, and career scientists of NIH, CDC and FDA. The Committee held an open meeting online on Thursday in order to present extensive information about the coronavirus, Covid-19, the role of the NIH in vaccine development and testing through Operation Warp Speed, the Vaccine Safety Team, problems of vaccine hesitancy, and criteria for Emergency Use Authorization and/or Biologic License Approval.  It was a full 8 hour meeting and enormous amounts of information were presented to the above committee and the public.  This was a way to make everything about the development of vaccines transparent and I watched all 8 hours.  Read Below.


This was not a meeting about specific vaccines being developed in the US.  It was a meeting to review the criteria that all vaccines must meet in order to apply for approval - based on an October 2020 document publishing the revised criteria for efficacy and safety.  I know that both Moderna and Pfizer/BioNTech are near the end of enrollment (30,000 and 44,000 volunteers of different ages, races, comorbidities).  But companies can't present data re: efficacy and safety until at least 50% of the volunteers are 2 months beyond their 2nd dose of vaccine   Each vaccine must be at least 50% efficacious, have 5 or more placebo patients with severe disease. and not have serious adverse effects.  I feel much better about the scientific rigor that will be required and I hope that both vaccines are able to meet all of the criteria outlined.   


October 21, 2020

Pregnancy and Covid-19

There is still a need for further clinical studies on the effect of SARS-CoV-2 on pregnancy.  In general it is recommended that women follow all the public health safety measures to prevent getting Covid-19 at all during pregnancy.  The studies show that Covid-19 is slightly more severe during pregnancy and there is a higher incidence of ventilators.  But there is no increase in mortality.  There is only very rare transmission of the virus to the babies, and it is not clear whether that occurred prior to or after delivery.  The babies rarely have problems due to the virus and it is not transmitted in breast milk. Mothers who want to breast feed are recommended to perform strict hand washing and mask wearing while feeding the babies. Read Below. 


Doctors at NYU Hospitals in New York studied 149 mother-child dyads and it is one of the largest studies published to date.  Forty% of the mothers were asymptomatic and picked up on screening.  15% of the symptomatic mothers required some type of respiratory support.  Symptomatic mothers had a significant increase in preterm births ( 16% vs 3%  P=0.02).  Only 1 newborn was + for SARS-CoV-2 and that was believed to have happened post-partum.  There were 3 sets of twins, 3 still births, and 1 post-natal death. (Publication in Pediatrics journal this month).

October 17, 2020

Sniffer Covid-19 Dogs

Sniffer Dogs Make the News:

Humans have 6 million receptors for smell in their nose, dogs have 300 million receptors, making them very good at detecting volatile organic compounds made in our bodies.   They have been trained to detect malaria infections, bacterial and viral infections, bombs, contraband in luggage, and some types of cancer.  Several weeks ago the New Your Times published a story about sniffer dogs being trained to detect infected covid-19 patients in the Helsinki airport.  Read More Below.


They trained 16 dogs and expect to have 10 in the airport by the end of November.  Six dogs weren't able to work in the noisy environment. 

The dogs can detect Covid-19 infections in less than 1 minute and can be used with a trainer to screen travelers in lines in airports.    The dogs can detect the Covid-19 infection in asymptomatic people, and test sensitivity is as high as 85 to near 100%, with equally high specificity. Dogs who have been trained for other scents can learn to detect Covid-19 infections in 1 week,   If they have never been trained with other scents, it takes significantly longer. 

Similar trials are being conducted in the UK, France, Germany, Lebanon and the US (at U Penn Vet School).   Dogs are being trained to sniff saliva, nasopharyngeal secretions, sweat, and urine.  In Helsinki passengers wipe their necks with a wipe and then put the wipe in a cup for testing.  

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