Pandemics in History

2019-20 SARS-CoV-2 Covid-19 pandemic

The Covid-19 coronavirus pandemic is an ongoing pandemic first identified in Wuhan, Hubei, China, in December 2019, and eventually officially declared a pandemic by the World Health Organization (WHO) on 11 March 2020.

According to Johns Hopkins University, as of May 5, 2020, more than 3,610,066 cases of COVID-19 have been reported in more than 187 countries and territories, resulting in more than 252,346 deaths.

While the Covid-19 pandemic has not yet ended, the numbers of infected and deaths reported so far are still nowhere near those of the 1918 Spanish flu and seem more on par with the estimated 250,000 to 500,000 deaths caused by the seasonal flu annually. It’s important to keep in mind we’re now only in the first wave of Covid-19 and the 20th century pandemic examples occurred in waves of illness of up to three waves over a 9-12 month period. Often the first wave was not the most severe. During the 1918 Pandemic, over 90% of the deaths of the pandemic occurred during the second wave.

Coronaviruses are actually a much larger group of related viruses that cause diseases in mammals and birds. In humans, coronaviruses cause respiratory tract infections that can be mild, such as some cases of the common cold (among other possible causes, predominantly rhinoviruses), and others that can be lethal, such as SARS, MERS.

The severity of a pandemic depends upon the virus that causes it and the SARS-CoV-2 coronavirus has proven to be particularly fatal to elderly humans with other underlying health conditions.

Covid-19 is the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Until recently, SARS was a relatively rare but lethal disease; at the end of the epidemic in June 2003, the incidence was 8,422 cases with a case fatality rate (CFR) of 11%. While the CFR varied depending on the age group of the patient, patients under 24 were least likely to die (less than 1%); those 65 and older were most likely to die (over 55%).

Middle East respiratory syndrome (MERS), is a viral respiratory infection caused by the MERS-coronavirus (MERS-CoV).  The disease is typically more severe in those with other health problems. Just under 2,000 cases have been reported as of 4 April 2017. About 36% of those who are diagnosed with the disease die from it.  As of 2020 there is no specific vaccine or treatment for the disease.

Historically pandemic influenza has caused widespread death and is a regular occurrence in history. Over thirty pandemics have happened in recorded history. All influenza pandemics infect many times more people than normal seasonal ( flu caused by viruses that are already among people) influenza outbreaks. In addition major pandemics can have severe adverse effects on the economy and daily life, as we’ve witnessed in the SARS-CoV-2 Wuhan coronavirus.

Flu pandemics occurred in the 20th century with differing levels of intensity.

The 1918 “Spanish Flu” Pandemic

A “major level event” pandemic that infected about 500 million people worldwide or one-third of the world’s population and accounted for over 50 million deaths. In America, the Spanish flu killed about 675,000 people.

Most influenza outbreaks disproportionately kill the very young and the very old, with a higher survival rate for those in between, but the Spanish flu pandemic resulted in a higher than expected mortality rate for young adults in the 20-40 year age group.

I believe we’ve learned allot since 1918 about how to deal with influenza, from improved mitigation through quarantine of infected patients to improved sanitary systems and better hygiene practices for all.

The Spanish flu was the first of two pandemics caused by the H1N1 influenza virus; the second was the swine flu in 2009.

The 2009 “Swine Flu” pandemic

The swine flu virus appeared to be a new strain of H1N1 that caused the Spanish flu pandemic. This new H1N1 virus contained a unique combination of influenza genes not previously identified in animals or people. This virus was designated as influenza A (H1N1)pdm09 virus. Some studies estimate that 11–21% of the global population at the time — or around 700 million–1.4 billion people — contracted H1N1 (more than the number of people infected by the Spanish flu pandemic), and resulted in about 151,000 to 575,000 fatalities. CDC estimated there were 60.8 million cases and 12,469 deaths in the United States due to the H1N1 virus.

On August 10, 2010, WHO declared an end to the global 2009 H1N1 influenza pandemic. However, (H1N1)pdm09 virus continues to circulate as a seasonal flu virus, and cause illness, hospitalization, and deaths worldwide every year.  Human seasonal flu vaccine will not protect against commonly circulating swine influenza viruses, but prescription influenza antiviral drugs can treat infections with these viruses in people.

The 1957-58 “Asian Flu” pandemic

A “minor level event” pandemic that accounted for 69,800 deaths in the United States alone. Estimates of worldwide deaths caused by this pandemic varies widely depending on source; ranging from 1 million to 4 million, with World Health Organization (WHO) settling on “about 2 million”.  Asian Flu was of the H2N2 sub-type (a notation that refers to the configuration of the hemagglutinin and neuraminidase proteins in the virus) of type A influenza.

The “Hong Kong Influenza” of 1968-69

A “minor level event “pandemic that killed an estimated one million people all over the world. It was caused by an H3N2 strain of the influenza A virus, descended from H2N2 through antigenic shift, a genetic process in which genes from multiple subtypes reassorted to form a new virus.

One fact is clear: we’ve had pandemics in the past and pandemics will occur again as these viruses mutate.