-Written by David Whittier

The COVID-19 situation we are facing these days is not a new occurrence in human experience.  On the contrary, history is rife with epidemics, pandemics, and plagues.  To provide a bit of context and perhaps illustrate some lessons from past events we can apply today, I share some research into influenza pandemics of the past 100 years.  This is not an exhaustive examination, just a few takeaways that might be useful.

For those who are limited for time, I have put some of the general observations at the beginning of this article, and a quick overview of each pandemic afterwards.  The biggest lesson we must learn: another strain is always just around the corner.  Pandemics have been with us since the dawn of history and will continue with us for the foreseeable future.

Some general observations from the research:

• There is no “business as usual” during a pandemic.  However, economic lockdown is a new phenomenon.
• There has never been a pandemic that did not have a “second wave”.
• Some experts recommend a focus on those who are known to be at high risk and thus more vulnerable to complications. This may be a better international approach rather than trying to look at a whole population approach using vaccines and antivirals.  For example, it may be more effective to identify that small number of people who develop more serious bacterial complications following influenza and then make sure that not only we give them promptly antivirals but also antibiotics.
• Widespread media coverage has induced panic in the population in the past, resulting in emergency departments being overwhelmed with requests for antivirals and then vaccinations.  This is likely to repeat itself.
• Given the inevitable delays in producing influenza vaccines, we need to re-examine how effective strategies based on mass vaccinations will be.
• hand hygiene and distancing approaches give good protection.  In Hong Kong during the SARS epidemic, for example, the widespread use of masks and hand hygiene by the population resulted in marked reduction in all respiratory illnesses.
• Referenced evidence suggests that using masks is protective compared to not using them.  However, since the value of masks outside of the medical environment is more to keep an infected person from transmitting droplets, there is no great difference in what type of mask to use.

Spanish Flu – 1918-1920

• around 500 million people around the world infected.
• at least 50 million deaths.
• impact made worse because of conditions of soldiers and poor wartime due to WW I.
•  disproportionately killed the healthiest: under 5 and 20-40 age groups, as well 65 and older. 
• no vaccine and no treatment (medical science at the time did not know that influenza was caused by a virus).  
• Most immediate and effective response was social distancing, which at the time was called “crowding control”.
• Officials downplayed the risk and stalled, mostly because of the timing (March 1918, during the height of WWI).  
• many authorities chose the economy over public health, resulting in a “second wave” in cases in October of 1918. 

Asian Flu: 1957-1958

• over 1.1 million deaths.
• Disease spread rapidly: Singapore in February of 1957, Hong Kong by April, and in the North American coast by summer.
•  infection spread in large gatherings – conferences and summer camps.
• Vaccine developed quickly: first outbreak in April 1957, US had vaccine by September. 
• Some disagreement in the medical community as to whether to encourage vaccinations or let the infection play its course and develop a “natural immunity”.
• In fall of 1957, a second wave swept through U.S. schools. A report published in 1959 estimated that “over 60 percent of students had clinical illnesses during the fall”
•  Illness was briefly harsh but rarely fatal. Inordinate effect on younger people.

Hong Kong Flu: 1968

• About 1 million deaths.
• Spread was slowed thanks to early detection and relatively quick vaccine development (Dr Maurice Hilleman in US bypassed regulatory agencies)
• People still went to work, but rode buses less often, washed their hands, and practiced social distancing.  
• Two waves: 68/69 and 69/70. In North America, most deaths occurred during the first wave.  In Europe and Asia, it was the second. In some cases, outbreaks were reduced by immunity some people still had from the Asian Flu.

H1N1 Swine Flu: 2009-2010

• Approx. 1.4 billion people infections and 151,700 and 575,400 deaths.
• 80% of the deaths were in people younger than 65
• H1N1 exposed the chronic lack of spare capacity in hospitals: overcrowding, bed block, and ambulance bypass occur regularly around the world 
• The  2010/2011 “second wave” of H1N1 had a smaller number of infected from the previous winter, apparently due to some immunity based on the previous winter’s infections.

References:
https://www.livescience.com/worst-epidemics-and-pandemics-in-history.html
https://www.webmd.com/lung/news/20200420/four-lessons-from-the-1918-spanish-flu-pandemic#1
https://www.seattletimes.com/seattle-news/health/lessons-to-be-learned-from-1957-pandemic/
https://www.nationalreview.com/2020/04/coronavirus-crisis-lessons-1968-hong-kong-flu-pandemic/
https://academic.oup.com/jid/article/192/2/233/856805
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3168221/
https://www.history.com/news/1957-flu-pandemic-vaccine-hilleman