Covid-19 Vaccines, Positive Results from Alberta Canada
With Covid-19 vaccines now becoming a reality, the question of their impact is naturally on peoples’ minds. Though it is early in most vaccination programs, there is some evidence regarding this question that is beginning to reveal itself.
In an earlier blog, I looked at how this is working out at the national level, by seeing how vaccination rates seem to be affecting Covid death rates in various countries, and whether countries with higher levels of vaccinations are bringing down those death rates faster than countries with lower vaccination rates. There was some evidence that this was, in fact, the truth. In this blog, I will look at a similar relationship, but in one particular jurisdiction, the province of Alberta, Canada, where I live.
Graph 1
Besides my obvious interest in my local situation, my use of Alberta as a test case is motivated by the fact that it has publicly available day-by-day data on Covid case rates, death rates and vaccination rates since this time (mid-March) in 2020, or most of the length of the pandemic (outside of China).
Graph 1 (Alberta Canada, Covid 19 Cases and Deaths by Day), shows the number of cases and deaths registered per day, over the last year. The left vertical axis refers to cases, and the right vertical axis refers to Covid-related deaths. Note that the scales are different, reflecting the fact that about 1-2% of covid cases resulted in a fatality during this period. Note also that the form of the two lines is very similar, though the line for deaths is shifted somewhat to the right of the line for cases.
Graph 2
The shifted lines reflects the fact that cases come before deaths (i.e. you can’t die from covid (or with covid) until you are infected with covid). There are a couple of ways to estimate what the lag time between cases and deaths is. One way is to shift one of the lines relative to the other (e.g. move the deaths line to the left), until they overlap and see how many days that shifting was. Another way it to calculate the correlation coefficient between cases and deaths at various lags to see where that correlation is at a maximum. You can see the result of those calculations (done in Excel with the corr function) in Graph 2.
Graph 3
In Graph 3, I shifted the Deaths line, making the lag between cases and deaths to be 14 days. One could have picked other lags, as Graph 2 indicates that any value between approximately 11 and 22 work pretty well. I suspect that the lag time actually changed during the pandemic, due to changes in reporting practices, the speed of diagnosis and the efficacy of treatments for the disease. I chose the value of 14 days since it was intermediate and it seemed to give the best fit for the latest big local wave of the pandemic, which is of primary interest.
Graph 4 is similar to Graph 3, but I smoothed out the data with a 7 day moving average to reduce the noise in the signal (the jittery lines become much smoother after calculating the average of the 7 values around each point, the 3 before, the point itself, and the 3 after).
In Graphs 3 and 4 you cans see how the line for Deaths and the line for Cases begins to depart some time around mid-January. That would indicate that the vaccinations began to cut into the death rates at about that time – cases remained stable ate about 350 per day and even rose, while deaths from about 5 per day to about 2-3 per day, indicating that the death rate as measured this way fell by about 40% or so.
Graph 4
A key factor here is related to the schedule of vaccinations, as shown in Graph 5 (the left vertical axis shows the cumulative number of vaccinations, while the right axis shows the percentage of the population that had been vaccinated). The vaccination program in Alberta began in mid-December with small numbers of vaccinations, then picked up significantly in early January, then slowed down in mid-January for a week or two, then ramped up again after that. That corresponds quite well with the time that the lines for Deaths and Cases separated, on Graphs 3 and 4.
Graph 5
As you can see, even by the end of the graph, the percentage of the population that had been vaccinated was still under 10%. So, why did vaccinating a relatively small proportion of the population have such a large effect?
That was because the first people vaccinated were those in nursing homes and similar facilities, then people over 75 in general. As in many places, in Alberta these were the populations most at risk, accounting for 65% or more of all Covid-related deaths. So, vaccinating that group was a high priority, and doing so really did cut the death rate substantially.
Graph 5 is a scatterplot that shows the percentage of the population that had been vaccinated versus the Case Fatality Rate. As you can see, as the vaccination rate goes up, the case fatality rate goes down. The function form at this time is basically linear, though a good case can be made for an exponential form, which fits the data a bit better (R-square=.72 vs .69 for the linear function). Over time, the graph will probably become more linear (e.g. exponential or quadratic), since the early gains from vaccinating the most vulnerable populations have already been baked into the cake. Vaccinating younger people will bring the case rate, but will not have a great effect on deaths, as they generally don’t die from Covid anyway.
Graph 6
Sources:
https://www.worldometers.info/coronavirus/#countries
https://github.com/owid/covid-19-data/tree/master/public/data/vaccinations
Some earlier Covid-19 blogs:
https://dodecahedronbooks.blogspot.com/2021/03/covid-19-vaccines-how-successfully-are.html
https://dodecahedronbooks.blogspot.com/2020/12/covid-19-vaccines-comparison-of.html
https://dodecahedronbooks.blogspot.com/2020/09/covid-19-continues-to-travel-around.html
https://dodecahedronbooks.blogspot.com/2020/07/has-covid-19-become-less-deadly.html
https://dodecahedronbooks.blogspot.com/2020/07/july-2020-update-covid-19-death-rates.html
https://dodecahedronbooks.blogspot.com/2020/05/covid-19-death-rates-correlate-highly.html
https://dodecahedronbooks.blogspot.com/2020/06/covid-19-impact-on-employment-no-impact.html
https://dodecahedronbooks.blogspot.com/2020/04/is-there-model-that-can-predict-when-to.html
https://dodecahedronbooks.blogspot.com/2020/03/estimating-fatality-rate-of-coronavirus.html
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And, here’s a more pleasant travel story than anticipating the worldwide journey of a virus.
A Drive Across Newfoundland
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Canada: https://www.amazon.ca/dp/B07NMR9WM8
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India: https://www.amazon.in/dp/B07NMR9WM8
Newfoundland, Canada’s most easterly province, is a region that is both fascinating in its unique culture and amazing in its vistas of stark beauty. The weather is often wild, with coastal regions known for steep cliffs and crashing waves (though tranquil beaches exist too). The inland areas are primarily Precambrian shield, dominated by forests, rivers, rock formations, and abundant wildlife. The province also features some of the Earth’s most remarkable geology, notably The Tablelands, where the mantle rocks of the Earth’s interior have been exposed at the surface, permitting one to explore an almost alien landscape, an opportunity available on only a few scattered regions of the planet.
The city of St. John’s is one of Canada’s most unique urban
areas, with a population that maintains many old traditions and cultural
aspects of the British Isles. That’s true of the rest of the province, as well,
where the people are friendly and inclined to chat amiably with visitors. Plus,
they talk with amusing accents and party hard, so what’s not to like?
This account focusses on a two-week road trip in October 2007, from St. John’s
in the southeast, to L’Anse aux Meadows in the far northwest, the only known
Viking settlement in North America. It also features a day hike visit to The
Tablelands, a remarkable and majestic geological feature. Even those who don’t
normally consider themselves very interested in geology will find themselves
awe-struck by these other-worldly landscapes.
A Ride on the Kettle Valley Rail Trail: A Biking Journal Kindle Edition
by Dale Olausen(Author), Helena Puumala(Editor)
The Kettle Valley
Rail Trail is one of the longest and most scenic biking and hiking trails in
Canada. It covers a good stretch of the south-central interior of British
Columbia, about 600 kilometers of scenic countryside. British Columbia is one
of the most beautiful areas of Canada, which is itself a beautiful country,
ideal for those who appreciate natural splendour and achievable adventure in
the great outdoors.
The trail passes through a great variety of geographical and geological
regions, from mountains to valleys, along scenic lakes and rivers, to dry
near-desert condition grasslands. It often features towering canyons, spanned
by a combination of high trestle bridges and long tunnels, as it passes through
wild, unpopulated country. At other times, it remains quite low, in populated
valleys, alongside spectacular water features such as beautiful Lake Okanagan,
an area that is home to hundreds of vineyards, as well as other civilized
comforts.
The trail is a nice test of one’s physical fitness, as well as one’s wits and
adaptability, as much of it does travel through true wilderness. The views are
spectacular, the wildlife is plentiful and the people are friendly. What more
could one ask for?
What follows is a journal of two summers of adventure, biking most of the trail
in the late 1990s. It is about 33,000 words in length (2 to 3 hours reading),
and contains numerous photographs of the trail. There are also sections
containing a brief history of the trail, geology, flora and fauna, and
associated information.
After reading this account, you should have a good sense of whether the trail is right for you. If you do decide to ride the trail, it will be an experience you will never forget.
Amazon U.S.: https://www.amazon.com/dp/B01GBG8JE0
Amazon U.K.: https://www.amazon.co.uk/dp/B01GBG8JE0
Amazon Germany: https://www.amazon.de/dp/B01GBG8JE0
Amazon Canada: https://www.amazon.ca/dp/B01GBG8JE0
Amazon Australia: https://www.amazon.com.au/dp/B01GBG8JE0
On the Road with Bronco Billy
Amazon U.S.: http://www.amazon.com/gp/product/B00X2IRHSK
Amazon U.K.: http://www.amazon.co.uk/gp/product/B00X2IRHSK
Amazon Germany: http://www.amazon.de/gp/product/B00X2IRHSK
Amazon Canada: http://www.amazon.ca/gp/product/B00X2IRHSK
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