Note: This article continues the Pandemic series which began with Pandemic Part 1: A Primer on the Biology of the SARS-CoV-2 Virus and the Terminology that You are Hearing and continues with Pandemic Part 3: Getting Your Flu Shot and Other Vaccines.
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To get perspective on a pandemic, such as the COVID-19 disease that is troubling humanity at the present time, sometimes its helpful to look back at pandemics of earlier eras. With this in mind, there are numerous infectious diseases that expanded in epidemic proportions throughout history. We could talk about bubonic plague, the Black Death that wiped out an estimated 30-60 percent the European population (estimated 75-200 million people) in the 14th century CE, or the Plague of Justinian in the 6th century CE (estimated death toll 25 million), which is thought to have been the same bubonic plague. We could talk about flu pandemic of 1889-1890 or what’s called the 6th cholera pandemic of early 20th century. We could devote an entire series of blog posts to possibly the most devastating human disease, smallpox, the first deadly infection to be eliminated with technology and the motivation for the most effective medical advance in history – vaccination. If there is any silver lining to the current COVID-19 pandemic it’s that it may shine a spotlight on the profound irrationality of the anti-vaccine movement. To spare you the historical megillah, however, let’s focus just a few pandemic diseases that have struck roughly within the past century.
One such disease that is still an issue today is HIV/AIDS. If you’re under age 30 and you don’t work in the healthcare industry, it’s quite possible that you don’t know much about it, other than whether you need to check ‘yes’ or ‘no’ in a box on medical forms or when donating blood, but it dominated the concern and efforts of global health agencies when it came on the scene in the 1980s. The disease –called acquired immune deficiency syndrome (AIDS) – is caused by a virus known as human immunodeficiency virus (HIV). Spread by sexual contact as well as by mechanisms involving the blood (including intravenous drug use, accidental needle sticks, an infusion of contaminated blood products), HIV/AIDS was first identified as affecting male homosexuals in particular, but then it was realized that it was a problem for heterosexuals as well. Being diagnosed with HIV infection used to be a death sentence, but many people are now living for many decades with the virus, with an increasing number of cases being declared as cured. This is due the development of treatments in which HIV patients take multiple drugs, each of which attacks the virus with a different tactic. One class of drugs, for instance, stops the cutting of certain viral proteins into other proteins that otherwise would enable the production of new virus particles. Another class of drugs interferes with a protein that otherwise would transcribe genes the viral genetic information molecule, known as RNA, into genes made of DNA, which then would integrate into the DNA of the infected person’s own cells. Such advances are the result of decades of research by dedicated scientists, such as Dr. David Ho. The most famous HIV survivor who owes his life to the multi-drug treatments is former NBA star, Magic Johnson, who has promoted HIV awareness around the world and helped to advance research by raising funds through his activism. However, HIV/AIS is still a major killer worldwide, especially in developing nations. Furthermore, even in places where the most advanced treatment and monitoring is available, health workers must devote a great deal of effort to the prevention of the spread of HIV.
In the years 1956-1958, humanity suffered a pandemic of a type of influenza that came to be known as Asian flu. After appearing in China in 1956, the disease spread to Singapore and Hong Kong and crossed the ocean to North America, where it killed almost 70,000 people, while taking the lives of an estimated 2 million people across the globe. A different flu developed a decade later in Hong Kong, Singapore, and Vietnam (which was in the midst of a war involving more than half a million American soldiers). From the middle to the end of 1968, this Hong Kong moved through India, Australia, the Philippines, the North America, and Europe, claiming more than 1 million lives, including roughly 15 percent of Hong Kong’s population. There have been many other influenza outbreaks more potent than the typical seasonal flu (which also kills thousands each year in the US alone), but as for the worse influenza of recorded history, nothing comes close to the so-called “Spanish Flu” of 1918-1919, with an estimated death toll of up to 50 million people. This dwarfed the number of deaths from the fighting of the First World War that was ending as the 1918 flu was breaking out. There were soldiers who narrowly escaped death over and over through the war from artillery, machine guns, and gas (chemical weapons), only to be cut down by the virus at the end of the war or in the subsequent months.
I say “so-called” in connection with the term “Spanish Flu”, because historians know that the idea of Spain as the pandemic’s epicenter was misconception –deriving from the fact that Spain was the only major country not to keep its numbers of cases and deaths secret from the media during the time when the disease was emerging on the world scene. The fact that soldiers died of Spanish Flu is significant, as the 1918 pandemic was notorious for killing people in their 20s to early 30s (those born from the late 1880s through the mid 1890s), much more so than children (born after 1900), or even elderly people (born in the mid 1800s). Scientists have suggested that the 1918 flu was more lethal in 20 somethings and 30 somethings, because their immune systems were trained to defend against a different type of influenza virus that had caused yet another pandemic, the pandemic of 1889 (mentioned in the introduction). In contrast, children and elderly had been exposed to flu viruses more similar to the 1918 virus when they had been babies and toddlers, so they could survive the 1918 flu more easily. The rationale for this hypothesis depends on some details of immunology, but the important thing to remember here is that the disease killed millions of young adults who lacked other health problems.
Consequently, when public health officials and infectious disease researchers encounter a new virus that develops into a pandemic, they evaluate potential outcomes with the 1918 pandemic hovering in their minds. This is happening in a major way when it comes to the current SARS-CoV-2, the virus that causes COVID-19 disease. It’s happening for two reasons: First, the fraction of people who die from the virus versus the total number of people who are infected (what doctors call the case fatality rate) is similar to that of the 1918 flu and maybe slightly higher, although, it is lower for healthy, young and middle age adults and children. Second, the ease with which COVID-19 disease spreads is also similar to that of the 1918 flu. Putting these two factors together suggests that COVID-19 has the ability to reach the level of the 1918 number of deaths. However, compared with a century ago, technology enables us to track the disease and take precautions much better. Furthermore, in the current century, we have the needed medical technology to rescue people who develop the most severe form of COVID-19. It’s the same technology that would have saved victims of the 1918 flu, because, with both diseases, death results from severe respiratory complications, basically severe pneumonia. To deal with that, doctors use mechanical ventilators that pump air into and out of the lungs. Antibiotics are useful, only against secondary infections consisting of bacteria complicating the viral infection, but there is a technology called extracorporeal membrane oxygenation (ECMO) –which is vital when the lungs simply cannot transmit enough oxygen into the blood, even with mechanical ventilation—would have seemed like science fiction to the people of 1918. To be sure, I’m oversimplifying the management of this new disease, which also depends greatly on a plethora of monitoring equipment and attention to things happening in organs other than the lungs.
When you put it all together, the challenge includes a need to develop new treatments, namely vaccines and medications that work specifically against the SARS-CoV-2, of which a handful are showing promise. One medication that has been in the news as a candidate drug is an old anti-malaria drug called chloroquine, but it’s possible value in treating COVID-19 is hotly debated. Possibly more promising are a few medications consisting of specially-made antibodies.
A still greater is the challenge of how to deal with thousands, and hopefully not millions, of severely ill people. Dealing with COVID-19 is a logistical problem, since the severe cases are manageable but with equipment, all in the setting of an intensive care unit (ICU). There are a limited number of ICU beds, a limited number of ventilators, a limited number of isolation rooms, even a limited number of special masks (N95 masks). Add to this the fact that ICUs must keep treating the non-COVID19 cases that would be coming in anyway, such as respiratory complications of the seasonal flu. Thus, while we have capabilities for dealing with the various plagues going back through history, even the notorious bubonic plague, curable today with simple antibiotics, there is a danger of overwhelming the system, as may be happening in certain locations in Europe.
In the next segment, we’ll talk about another infectious disease that grew to epidemic proportions at some point in history. I’m talking about polio, which we shall use as the basis for discussing how easily we can prevent a plethora of diseases with vaccines, and we’ll do that against the backdrop of the current COVID-19 pandemic.