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.
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.
When I created this blog, I wanted it to include my earlier Virus Info email messages. So I simply copied and pasted each email into a blog post. They all looked good.
Then a reader informed me he was seeing image.pnginstead of images in one of the blogs.
I found that Firefox in Windows and Safari on my iPad had this problem. I had never seen any of these broken images because I always use Chrome.
For my blog I use the platform WordPress. I compose the blog message in a word processing type window. WordPress converts it to HTML so that it will display on a website. Clearly it was not generating the correct HTML for all browsers.
WordPress is big, really big.
“WordPress is the most popular web management system in the world and is used by nearly 75 million websites. According to WordPress, more than 409 million people view more than 23.6 billion pages each month and users produce 69.5 million new posts and 46.8 million new comments every month.”
So how could my simple copy and paste fail so badly?
Software bugs.
Trying to contact WordPress for help to correct this would have been a long, arduous process. So I did some experimentation and found a way to “fix” this myself. In each blog, I saved the images separately to my computer, deleted them from the blog message and then copied in the saved images.
Canadian news about Covid-19 has generally been pretty positive about the progress being made to contain the virus across Canada.
American news has been obsessed, for good reason, about the outbreaks occurring all over the country.
But you don’t see many reports about Europe. Many countries in Europe had major outbreaks before we even saw very many cases in North America. They have contained the virus far better. Our health “experts” probably could learn a lot from the Europeans, but I’ve never seen any indication that they communicate with them very much. This is doubly true for Asia. Many Asian countries have done a far better job from the beginning than Europe and certainly North America (noted in several earlier blogs). When’s the last time you saw an Asian virologist interviewed on our news?
Here’s the proof in pictures.
U.S.
Canada
Italy and Spain had the worst outbreaks in Europe, but they have brought their cases down much faster than Canada and to a much lower level.
When you signed up with an Internet Service Provider (ISP) you probably got a range of options for download speed, ranging from 10 Mbps (Megabits per second) up to 1 Gbps per second (1000 Mbps).
A byte is 8 bits, so 10 Mbps is 1.25 MB per second.
At 50 Mbps (40 MB/s), you will get good Internet access including HD (High-definition) streaming and online gaming. Plus you can share the connection with 3–4 other computers without noticing a slowdown. You can download high resolution photos in seconds and HD videos in just a few minutes.
Let’s suppose you have 50 Mbps service. Can you actually download data from the Internet this fast?
It depends on the Wi-Fi speed between your computer and the router. Here’s a typical home set up for your Internet connection. Anything using the Internet has to first send the data over the Wi-Fi network.
Wi-Fi is subject to a lot of noise interference (see the previous blog). Generally, the further your computer is from the router the slower your Wi-Fi connection is going to be because of interference from walls, ceilings and any other large objects in the path.
The Wi-Fi is network is shared among all the computers in your house so you need to run this from each device that uses the Internet. If you find that some of your Wi-Fi speeds are low, you should see if you can move the router and/or the computer so they are closer together.
Then add up all the Wi-Fi download speeds to see if your Internet connection is fast enough when all computers are streaming video. If the Wi-Fi total is greater than your Internet speed on your plan, you might want to consider upgrading to a higher speed. But if the Wi-Fi total is less than your Internet plan, you may want to change your Internet plan so you are paying for only the speed you can use.
I was happily working on my computer in my home office the other day and suddenly most of the tabs in my browser reported a network error.
Like most home Internet setups, my computer uses a Wi-Fi wireless connection to connect to the router provided by my Internet Service Provider (ISP). The router connects to a modem that sends your request to the ISP network where it gets forwarded on to the Internet.
I went into the Wi-Fi settings on my Windows computer, disconnected the Wi-Fi and then reconnected it. You can find the Wi-Fi settings by using the Search on the Taskbar (magnifying glass icon).
I went back to work and for a time everything was fine. But then I lost the Wi-Fi again. I checked on my mobile phone and it still had a Wi-Fi connection. So there was no problem with the Wi-Fi router, it was strictly a local problem on my computer.
I looked along a line of sight from my computer to the router which was downstairs in the kitchen and tried to think of what might be blocking the signal. Well right front of me I saw that the door to my room was closed. Now I often work with the door closed but this time on a hunch I got up and opened the door. Now after I reset the Wi-Fi it worked for the rest of the day without any further outages.
Why did this happen?
Wi-Fi is a radio signal. As such, it is subject to all kinds of noise disruptions. If you have ever listened to an analog radio, you know that there is often interference and you get crackle and other noises. For a digital signal such as Wi-Fi, the tiniest little noise that you wouldn’t even notice on a radio is enough to signal an error. Internet data is sent in packets typically about 1,500 bytes long. Any error in the packet means that the whole packet is discarded and the sender has to transmit the whole packet again. So a small amount of interference or noise on your Wi-Fi connection can create a lot of retransmissions that result in long delays when you are trying to use the Internet.
A major source of interference in our house is the microwave oven. Microwave uses radio signals that are in the same frequency band as our Wi-Fi, the 2.4 GHz frequency band. Our Internet router is in the kitchen and whenever the microwave is on it effectively knocks out the Internet for everybody.
Cordless phones, baby monitors and garage door openers also use the 2.4 GHz frequency band, so they can also interfere with your Wi-Fi.
Some routers support another Wi-Fi frequency band, at 5 GHz. If your router has this option, you will see another Wi-Fi network name in your device’s WiFi settings. You might want to consider using it instead of 2.4 GHz.
5 GHz is faster and less prone to interference from other devices since fewer devices use this frequency. However 5 GHz may have a smaller coverage area and is less successful at penetrating solid objects.
So computers that aren’t too far from the router should use 5 GHz. But mobile phones which move around and may be farther away from the router should use 2.4 GHz.
We were looking forward to a lovely dinner at a restaurant in Rome. I checked Google maps on my phone for the directions. It was about a 15 minute walk and looked pretty straightforward. Every few blocks I checked the map because there were a lot of turns onto small streets.
After about 15 minutes, I noticed that the street corner I was approaching looked kind of familiar. Sure enough, we had been there earlier. While I was scratching my head, my wife asked a shopkeeper for directions. Ignoring my phone, we were able to follow the directions and arrive at the restaurant.
But it was too late; it was a very popular restaurant and they had given our reservation to someone else. But in Rome this is not a problem. There are so many restaurants that we had no trouble finding one nearby on the lovely Piazza Navona and had a thoroughly enjoyable dinner.
So what in the world had caused the directions on my phone to fail so badly?
I knew that mobile phones have a radio receiver that reads signals from GPS satellites (Global Positioning System) that are continually broadcasting their position and time. The phone’s position can be calculated by solving for four unknown quantities — latitude, longitude, altitude and the time it took for the signal to travel from the satellite to your location. If you remember some high school algebra, you know that solving for four unknowns requires four equations. So your mobile phone needs to get GPS readings from four satellites.
I also knew that GPS signals could be obstructed when you were surrounded by tall buildings, such as in Manhattan, downtown New York City. But Rome, and certainly where we were, does not have very high buildings. On the other hand, the streets are extremely narrow so there is not much sky visible. This was probably the reason I did not get the right directions on my phone.
View of the sky in a narrow street in Rome
What is the lesson to be learned from this?
Simple. If you suspect that your GPS may not be accurate, look up at the sky. If you can’t see lot of sky, your GPS may not work. However, this does not necessarily mean that your map directions will fail because mobile phones also use cell phone towers to determine location, but it may not be as accurate as GPS which determines location to within 5 meters.
Historical note: The first GPS system was developed for the U.S. military during the cold war. In 1983 a passenger plane on route from New York City to Korea entered prohibited airspace because of navigational errors and was shot down by Russia (the Soviet Union). After this, the U.S. made GPS available for civilian use to try and avoid such disasters. Not long after this, Russia also made their satellite system available for civilian use. Many smartphones will use the Russian satellites as well as GPS. Europe and China are also developing navigational satellite systems.
It seems clear now that many States that opened too early at the end of May has led to an increase in Covid-19 cases in the US.
By contrast, in Canada where opening has been more gradual and is still in progress, new cases continue to decline.
Many states (red on map) are seeing increases in the daily number of cases. The three largest states in the US — California, Texas, Florida — are setting records for the highest number of new daily cases since the pandemic began. Texas has just started to reimpose some lockdown restrictions. Many other states will likely be forced to do the same.
This spike in cases does not disprove the alternate theories reviewed in the previous email, which basically held that the virus would not spread at epidemic rates because population immunity had become 50% or more. Those theories could still be true and in the US the virus is spreading because their immunity level is under 50%.
These alternate theories used UK data to arrive at the conclusion that immunity in the UK could be more than 50%. The real test of these theories will be what happens in the UK. The UK is still in various stages of lockdown, but on July 4, pubs, bars and restaurants reopen. If people do not adhere to social distancing guidelines, there could be a spike in cases, as in the US, or there could be no spike if the theories about immunity in the UK are true.
Indications are that social distancing guidelines will not be followed very well, as seen in the rush to Bournemouth Beach last weekend. This is similar to scenes from California and Florida.
In the June 3 post, I expressed a strong opinion that the health authorities have bungled dealing with face masks and that they should be strongly recommended.
It turns out there are Open Letters to Dr. Tam (Chief Public Health Officer of Canada) and the top health officials in Albert, Ontario and Quebec recommending mandatory face masks under specific conditions. To date there are about 1400 people who have signed these letters, almost all are health practitioners and it looks like more than 50% are MD’s.
