gada [dot] space

Comparing the 1918-19 Spanish Flu to the COVID-19 Pandemic

Disclaimer: I’m not an epidemilogist

As we all live through a global pandemic in 2020, there is some real uncertainty about when things will get back to normal. Based on our experience in 1918-19, how bad is the current pandemic on a relative scale? What is different now? Are we in a better or worse position to face the pandemic in contrast to the conditions in 1919?

Markel, Lipman et. al. look at nonpharmaceutical interventions (read physical distancing, school closures etc.) and Excess Death Rate (deaths recorded over estimated weekly baselines of pneumonia and influenza deaths, normalized per 100,000 population, EDR).

This figure summarizes the impact by US geographical zones:

Figure 1: Excess Death Rate over 24 weeks [1]

Figure 1: Excess Death Rate over 24 weeks [1]

A few super-high-level analyses:

1918-19 Influenza Pandemic

  • 675,000 US deaths (estimated 17-50MM worldwide)
  • There were 3 waves
  • Starts March 1918 and ends June 1919 (64 weeks)

Figure 1 above shows the trend of Flu spread from September 1918 to February 1919 (24 weeks). Some observations:

  • Region East had a lead during the acceleration phase and hit the highest peak EDR among the 3 regions. During the current pandemic as well, the East is the worst hit. One difference: in 1918, the East was hit before the West, while in 2019, the first case was recorded in the West.
  • Region East hit a peak and there were no significant waves once things slowed down. If history does repeat itself, the East has already seen the worst of it and things will get better from here.
  • Region West was affected by another wave, almost half the magnitude of the first peak 11 weeks after things started slowing down which means we can never be too careful!
  • Regions Midwest and South had the smallest initial peak among the 3 zones, although they later faced a resurgent 2nd wave. Their 2nd wave peak came 8 weeks later, picking up right after the 2nd wave in the West started slowing down. This was also the highest resurgent peak – again meaning we can never be too careful! This wave-peak is ~1/3rd magnitude of the tallest peak.

2019-2020 Novel Coronavirus

(as of 26th April 2020)

  • 55,000 deaths
  • First case detected January 22
  • We’re in the 14th week right now
  • National mortality rate - 4.02%

If we assume mortality remains constant at 4.02%, we will cross 1919 pandemic fatalities (675k) in 10 weeks. However, the mortality rates are on a deceleration path. We have already flattened the peak in many states. The day over day death counts are decreasing in New York. Moreover doctors and frontline health workers have better techniques and are learning new ones on a weekly basis to treat patients. It is therefore a reasonable supposition that mortality rates will continue slowing down in the next 10 weeks, unless we see another unprecedented wave.

Let’s try to calculate EDR, for NY state.

  • 16,966 coronavirus deaths as of writing.
  • 19,765,664 population (baking in a conservative 2% population rise into the 2010 census figure)
  • Assuming 4.02% (national average) mortality rate over the next 10 weeks.

The EDR is then 586.6. Note, the mortality rate in NY right now is 1.68%, which equates to 270 EDR. The EDR for the 1918-19 Flu ranged from 210.5 for Grand Rapids, MI to 806.8 for Pittsburgh, PA; the least and worst hit cities respectively.

Based on what we know so far from the last pandemic, let’s answer the questions we asked initially.

How bad is the current pandemic on a relative scale?

  • We’re currently at less than a 10th of the total fatality counts recorded during the Spanish Flu
  • There is a real possibility of another wave, which based on history could go up to 1/3 peak magnitude in 10 weeks if distancing guidelines change and care levels drop. Monitoring mortality rates closely will help us detect and prepare for wave supression tactics.
  • We’re currently 14 weeks through. The 1918-19 pandemic lasted 64 weeks. On that relative timeline, we can expect 50 weeks for resumption of normal life.
  • If mortality rates remain at current levels (unlikely, worst case assumption), it will take only 10 weeks to cross 1919 death counts.
  • Assuming a constant mortality rate of 1.68% in NY, the EDR comes out to be 270. In contrast, during the Spanish Flu, measured across 43 US cities, EDR ranged from 210.5 to 806.8.

Are we better or worse prepared compared to 1919?

Compared to 1919, we have some key advantages:

  • Rate of Information Dispersal

    With real time information dispersal, we are much better equipped to get notified about an outbreak in the neighborhood, workplace, city or state compared to 1919. As a consequence, travel choices can be much more informed.

    Collaboration and cross-pollination of ideas is also at an all time high. Any novel and effective technique discovered can spread around the world in a matter of days (vs. months).

    Due to this near real-time speed of information dispersal, we are better suited to monitor mortality upticks and nip waves in the bud.

  • We didn’t just face a World War

    In 1919, the WWI had just ended. People were tired of the war. The general morale of the public was at an all time low. There was a lot of cross-border movement of armed forces and refugees due to the war. Today, there’s a near shut-down of travel.

  • Sanitization and Health Care

    Compared to 1919, we have much better sanitization around the world and more advance healthcare systems and solutions. We can already see fast adoption of cleaning and sanitation tools and techniques across the country.

When will things get back to normal?

The million dollar question – when will things get back to normal? A safe answer based on historical knowledge: Not any sooner than what it took us last time, i.e. 64 weeks. We’re are currently in the 14th week.

Let’s round up to a year.

Seeing how fatalities are slowing down, and with the relative advantages we have over the early-1900s, can normal life can resume in half that time, say 25 weeks? Close monitoring of mortality rates, co-ordinated state response to tackle subsequent waves, rapid information sharing, interstate and international travel bans for another 6 months might just help us get there – and I really hope we do!

Perhaps, another thing will help – truth, owning, not shrugging responsibility, some humility. That’s a tough nut to crack in our current times. Thanks leader – we all need that miracle soon.

References

  1. Aledort, Julia E, Nicole Lurie, Jeffrey Wasserman, and Samuel A Bozzette. “Non-Pharmaceutical Public Health Interventions for Pandemic Influenza: An Evaluation of the Evidence Base.” BMC Public Health 7, no. 1 (2007): 208.
Menu