Ernie Dainow's Blog

Two major Covid-19 vaccines have started phase 3 clinical trials and are expected to complete by the end of 2020. If the results prove to be significant and safe and receive fast track FDA approval, there should be vaccines available in the first half of 2021.

The University of Oxford trial is recruiting 50,000 volunteers and the Moderna trial is enrolling 30,000 subjects. Both companies are proceeding with parallel plans to manufacture the vaccine so that if approved there will be minimal delay before the vaccines are available.

There is also recent news of a Covid-19 vaccine developed by Russia.  Under revised Russian law, the vaccine has been released before a phase 3 clinical trial has been completed. This has received widespread condemnation for being unsafe.
https://www.cnn.com/2020/08/11/europe/russia-coronavirus-vaccine-putin-intl/index.html

In fact what the Russians are doing may not be that different. The Moderna and Oxford trials are trying a drug on an experimental basis on 80,000 people, before any phase 3 trial results are known. If the Russians review the results of their vaccine after it has been given to 50,000 patients, they may determine that the vaccine is not safe and/or not effective and may withdraw it. This is not very different from the Oxford trial.

What really irks the U.S. and U.K. is that Russia, like Oxford and Moderna is proceeding with manufacturing the vaccine, but has jumped ahead of them by making deals with 20 countries to sell them more than one billion doses of their vaccine.

So what is the impact of having a Covid-19 vaccine in early 2021?

We ran a model simulation for Canada. If 100,000 people per day can be vaccinated starting in April 2021, then by the end of Oct 2021, daily coronavirus cases decline to 0. At that point population immunity is 60%. This would be “herd” immunity.

This result is generic and can be applied to any country. If a country can vaccinate 0.25% of its population per day, it can achieve herd immunity in 8 months.

When Covid-19 cases began to rise in the U.S. in March, testing was a major point of contention. There were differing opinions as to whether enough testing was or could be done. A lot of testing was delayed after it became clear that the tests developed by the CDC were faulty. In an effort to counteract this shortage of tests, the FDA allowed many test kits to be sold without any validation. This led to perhaps an even worse situation. A detailed report by 60 Minutes shows what a disaster this was.
https://www.cbsnews.com/video/coronavirus-antibody-testing-inaccurate-data-60-minutes-2020-06-28/

With the pandemic in the U.S. spreading so rapidly since June, many people do not believe it is possible to test enough people and get results fast enough to control the virus. Most states are far below the minimum testing target.
https://www.nytimes.com/interactive/2020/us/coronavirus-testing.html

However, this conclusion is based on the testing technology that is currently in widespread use, namely a molecular diagnostic test of a nasal or throat swab. There are other techniques that are much more efficient, faster and cheaper. These may be able to close the current testing gap so that testing can be used to get better control of the virus and reduce how fast it is spreading.

Pooled sampling combines samples from several people and tests them in a single test. If the test is negative, it saves testing each of the samples. If the test is positive, then each sample does need to be tested. This technique was actually developed during World War II. Basic pooled testing was given “emergency use authorization” for Covid-19 testing by the FDA on July 18, 2020.

But there are newer more efficient pooled testing techniques. Using a mathematical model based on a “hypercube” can minimize the number of tests needed to isolate the positive cases and so can use larger sample sizes. This approach has been successfully used in Rwanda.
https://theconversation.com/rwandas-covid-19-pool-testing-a-savvy-option-where-theres-low-viral-prevalence-141704

Another very promising direction is cheap at home tests. This will allow very large scale testing without the detrimental time delays of waiting for a lab to process the sample. The following reports a really simple and fast test that is in late development. You simply spit into a test tube and insert a paper strip that will change color in 15 minutes if the virus is detected.
https://www.nytimes.com/2020/07/03/opinion/coronavirus-tests.html

New testing techniques such as these are potential “game-changers” in controlling the spread of the coronavirus.

There is a growing sense in the U.S. that the epidemic is now unstoppable. Each state, city and rural area has their own crisis. Hot spots can suddenly turn up anywhere. A small outbreak in Alaska has been one of the country’s fastest-spreading for three weeks, while transmission in Texas and Arizona has slowed.

Perhaps 10% of the infected account for 80% of new cases. Unpredictable super spreading events in nursing homes, meatpacking plants, churches and bars are major drivers of the epidemic.

Contact tracing is moot, there are too many cases to track.

None of the medicines for which hopes were once high (AIDS drugs, antivirals and malaria drugs) have proved to be cures. Experts familiar with vaccine and drug manufacturing are disappointed that, thus far, only dexamethasone and remdesivir have proved to be effective treatments, and they are limited to special circumstances.

Read more at
https://www.nytimes.com/2020/07/29/health/coronavirus-future-america.html

Six months of a global pandemic have stirred an unprecedented amount of research. While many things about Covid-19 have been discovered, a lot of research has produced incomplete and sometimes contradictory results.

These are the pressing questions that do not have answers yet.

1. Why do people respond so differently?

Some people have mild symptoms or even no symptoms and don’t know they are infected. While most reactions are respiratory there are also cases of heart and blood vessel damage and kidney failure. Many people require hospitalization, some end up in an Intensive Care Unit (ICU) and many people die from Covid-19.

2. What’s the nature of immunity and how long does it last?

Studies have found that the level of antibodies produced by the immune system when someone has been infected with Covid-19 can vary quite a lot. It is not known what level of antibodies are necessary to provide immunity or how long it lasts.

3. Has the virus developed more dangerous new mutations?

Molecular biologists can determine the genetic mutations in Covid-19 and use this information to track how the virus has spread from one region to another around the world. But it is not known if any of these mutations are more virulent or transmissible than others.

4. How well will vaccines work?

Some vaccines might work well at preventing lung infections but not infections elsewhere in the body. Some vaccines may produce enough antibodies to work for some people but not enough to protect others from infection.

5. What is the origin of virus?

There is general agreement that the virus originated in bats. Scientist are able to compare the Covid-19 genome to the genomes of coronaviruses found in different bats and other animals. So far, there are genetic differences that are too large to conclude what the original source might be.

For a more complete report on these questions and the research that has been done see
https://www.nature.com/articles/d41586-020-01989-z

Television news loves to show pictures of crowded beaches as examples of how people are ignoring social distancing guidelines. In some cases this may be true, but in many cases they have just lost perspective.

Here’s a photo of a beach that looks overcrowded.

But that’s because you are looking at a long stretch of beach along the shore line.

When you look at the same beach, looking towards the water, you can clearly see that there is easily more than 6 feet between groups of people.

The responsible way for television to report overcrowding at a beach would be with an aerial view.

As lockdown restrictions are relaxed and people go out more, what is the probability of actually encountering someone who has Covid-19 and is contagious?

Someone who has Covid-19 is infectious for 14 days but may not show symptoms for first 5 days (the mean). Once they have symptoms they will be either in quarantine or in the hospital. So your risk of encountering someone who is contagious is during the 5 days before they had symptoms. But there is no way of knowing how many such people there are, it may take up to 5 days before they have symptoms and can be counted. As a good approximation you can use the total number of new cases in the last 5 days.

In addition, many cases are unreported because people do not have any symptoms (asymptomatic) or their symptoms are so mild that they don’t realize they are sick. So add 10 times the total 5 day case count to include the unreported cases, based on this CDC analysis.
https://www.nytimes.com/2020/06/27/health/coronavirus-antibodies-asymptomatic.html?referringSource=articleShare

Then divide by the population of your location to get the probability that any random person is infected.

For Toronto this probability is .07% about 7 out of 10,000.

Rather than meeting a single person, what about meeting another couple at a restaurant where there are two more couples at adjoining tables and one server?

Using high school math you can calculate the probability that one or more of these 7 people are contagious.

This probability is .5% about 1 out of 200.

This is a fairly low risk of encountering someone who could infect you. There is additional risk of airborne infection but not enough is known to estimate its probability (see previous blog).

But the more people in a group, the higher the probability. If you go to a house party where there are 25 other people, the probability that at least one person is contagious is 1.7%

Low probabilities do not mean that you can skip the social distancing rules. If everyone does that it will increase the spread of the virus, slowly at first since it is low probability but more rapidly as cases increase and the probabilities increase.

On July 9, WHO (World Health Organization) acknowledged that the coronavirus can spread through tiny droplets floating in the air, after more than 200 experts in aerosol science complained that the agency had failed to warn the public about this risk.
https://news.yahoo.com/pandemic-exposes-scientific-rift-over-204543074.html

There were a few early cases of Covid-19 that suggested it was transmitted by airborne particles. A very dramatic case was the choir in Washington state that held a rehearsal with 60 members on March 10. Three weeks later 45 people were infected and two died.
https://www.latimes.com/world-nation/story/2020-03-29/coronavirus-choir-outbreak

This risk of airborne transmission is highest in crowded indoor spaces with poor ventilation and may help explain super-spreading events reported in meatpacking plants, churches and restaurants.

What can you do to reduce your risk of exposure to airborne transmission?

– Avoid crowded indoor places, close-contact settings and confined spaces with poor ventilation.
– At home, open windows and doors whenever possible.
– Upgrade the filters in your furnace/air-conditioning system and adjust the settings to use more outdoor air.

https://www.nytimes.com/2020/07/06/health/coronavirus-airborne-aerosols.html