Can this be right?
The author is not some rando blogger at Medium. According to his mini-bio:
About Eyal Shahar
Professor Emeritus of Public Health (University of Arizona);
MD (Tel-Aviv University, Israel);
MPH, Epidemiology (University of Minnesota)
Via Medium, May 27:
Counting the dead used to be the work of epidemiologists, statisticians and demographers. So was analyzing the numbers and drawing conclusions. In the past year many are counting deaths, but the numbers have no meaning without the context of a relevant time period, population and history. That is, epidemiology.
The most counted country is probably Sweden, a stubborn dissenter that refused lockdowns, mask mandates and contact tracing. By the time of this writing, 14,349 Swedes have reportedly died from the coronavirus. Has the Swedish model failed? Were the lockdowns justified? Were the economic and social upheavals in most of the world an unavoidable necessity?
The answer to all is a resounding no. The first (and not the only) witness: Sweden. To understand the testimony, we need to learn only two concepts: “flu year” and “excess mortality”.
“Flu year” versus calendar year
Many calculate mortality statistics according to the Gregorian calendar, but December 31st is not a meaningful end date for winter mortality in the northern hemisphere. The flu wave and the associated wave of mortality reach the peak at various dates, and sometimes secondary waves appear. Furthermore, the use of the Gregorian calendar combines the mortality in the first part of one winter (sometimes mild) with mortality in the second part of the previous winter (sometimes severe). There is no scientific justification for this grouping when analyzing historical trends.
The statistical alternative, which may be called “flu year”, contains a full winter season. Annual mortality is calculated from the beginning of the flu season, which is usually counted from week 40 (early October), till week 39 in the following year (end of September). Thus, the coronavirus waves in the spring and summer of 2020 belong to the 2019–2020 flu year, whereas the last winter wave belongs to the current flu year which will end in September.
Excess mortality
The concept of “excess mortality” is a little abstract. We need to compare actual mortality with “expected mortality”, but the latter is a theoretical idea that cannot be verified: what would the mortality in the 2019–2020 flu year have been, had there not been a pandemic? How do we calculate “expected mortality”?
One method uses a statistical model called linear regression. We fit a line to the mortality data from previous years, check its past performance, and use the continuation of the line to compute expected mortality. The distance between a data point of actual mortality and expected mortality on the line is excess mortality (or “mortality deficit”).
Mortality in Sweden by flu year
The graph shows the annual mortality in Sweden per million people in the last 22 flu years, where each flu year is labeled according to the calendar year in which it ends. For example, the last data point on the graph is mortality between October 2019 and September 2020: 9,234 per million people (95,365 deaths). To magnify, the vertical axis starts at 7,000.
Source: SCB.SE
It is easy to see that the points are located close to a straight line, until the flu year that ended in September 2018. The general downward trend reflects a consistent increase in life expectancy in Sweden for many years.
Experienced data analysts will attest that the fluctuations around the line are generally small and expected until 2018 (explained variation: 0.96). In contrast, both the flu year that preceded the pandemic (2018–2019) and the pandemic year (2019–2020) substantially deviate from the line: the former — in lower than expected mortality, and the latter — in higher than expected mortality.
Excess mortality in Sweden in flu year 2019–2020
Continuation of the line, which was fit by the statistical model, yields the following estimates: In 2018–2019 there was “mortality deficit” in Sweden of 300 per million people (-3.3%) whereas in 2019–2020, the pandemic year, there was excess mortality of 364 per million people (+4.1%). Excess mortality following mortality deficit, and vice versa, are well known and expected, as the main source of mortality is an elderly population with limited life expectancy. (The sequence “excess after deficit” is, of course, better than the reverse order.)
Assuming the excess mortality in 2019–2020 “fully balanced” the mortality deficit in the previous flu year, the true excess mortality in Sweden was less than 1% (about 700 deaths). And if we assume, absurdly, that the mortality in 2019–2020 was not affected at all by the mortality deficit in the previous flu year, then the excess mortality in Sweden did not exceed 4.1% (about 3,800 deaths). Excess mortality of a few percentage points, or more, has been calculated in many countries where life has been severely disrupted. Part of that excess has been attributed to lockdown and panic.....
....MUCH MORE
Not a nutritionist playing off of a tenuous Harvard connection, not a finance blogger, not an opinionated opiniator, but an honest-to-goodness epidemiologist who's been doing it long enough to be granted emeritus status.
