The topic for this chapter is pretty self explanatory, so I will jump right into the meat of it.

I will start by explaining and defining a few terms, I believe that this is where most of our confusion arises from and that in many cases there is confusion arising from a lack of understanding of the subject or a lack of knowledge of the terms being used. Terms that are commonly bandied about in regards to viral deluges are the following, pandemic, epidemic and outbreak.

An outbreak is when an illness happens in unexpected high numbers. It may stay in one area or extend more widely. An outbreak can last days or years. Sometimes, experts consider a single case of a contagious disease to be an outbreak. This may be true if it’s an unknown disease, if it’s new to a community, or if it’s been absent from a population for a long time.

An epidemic is when an infectious disease spreads quickly to more people than experts would expect. It usually affects a larger area than an outbreak.

A pandemic is a disease outbreak that spreads across countries or continents. It affects more people and takes more lives than an epidemic. The World Health Organization (WHO) declared COVID-19 to be a pandemic when it became clear that the illness was severe and that it was spreading quickly over a wide area.

There is a system of phases that helps to describe how these viruses are spread.

The WHO’s pandemic alert system ranges from Phase 1 (a low risk) to Phase 6 (a full pandemic):

• Phase 1: A virus in animals has caused no known infections in humans.
• Phase 2: An animal virus has caused infection in humans.
• Phase 3: There are scattered cases or small clusters of disease in humans. If the illness is spreading from human to human, it’s not broad enough to cause community-level outbreaks.
• Phase 4: The disease is spreading from person to person with confirmed outbreaks at the community level.
• Phase 5: The disease is spreading between humans in more than one country of one of the WHO regions.
• Phase 6: At least one more country, in a different region from Phase 5, has community-level outbreaks.

Even though we may not have cures or vaccines for these epidemics and outbreaks there are simple ways that we can mitigate the effects of them.

Prevention: Slowing the Spread of Pandemic Disease

There’s no sure way to prevent the spread of disease during an outbreak, epidemic, or pandemic. It might take scientists a long time to make a vaccine. But it’s easier to make specific vaccines more quickly now than it was several years ago. Once a vaccine is ready, people and groups who are more likely to become ill will get it first.

In the meantime, you can take other steps to stay healthy:

• Wash your hands often with soap and water. If that’s not an option, use an alcohol-based hand cleaner or gel sanitizer. Rub it on your hands until they’re dry.
• Don’t touch your mouth, nose, and eyes unless you’ve just washed your hands.
• When you cough or sneeze, cover your mouth and nose with a tissue. Then throw the tissue in the trash. Wash your hands afterward.
• Avoid crowded places. Stay home if you can.
• Clean and disinfect household surfaces every day.

If you get sick:

• Stay home and away from other people. If you want to talk to your doctor, call before you go to their office. But if you have severe symptoms like trouble breathing, call 911 or go to an emergency room right away.
• Wear a face mask if you have to go out for medical care. Avoid public transportation, ride-hailing, and taxis.
• Have only one person care for you, if possible.
• Wash your hands often, and keep household surfaces clean and disinfected.

The Origin and history of Pandemics

Despite the fact that most emerging diseases stem from the transmission of pathogenic agents from animals to humans, the factors that mediate this process are still ill defined. What is known, however, is that the interface between humans and animals is of paramount importance in the process.

I came across a posting in history.com, entitled “Pandemics That Changed History.” The article was so well done, that I can’t improve on it, so I have included it in its entirety below.

Circa 3000 B.C.: PREHISTORIC EPIDEMIC

About 5,000 years ago, an epidemic wiped out a prehistoric village in China. The bodies of the dead were piled inside a house that was later burned down. No age group was spared, as the skeletons of juveniles, young adults and middle-age people were found inside the house. 

The archaeological site is now called “Hamin Mangha” and is one of the best-preserved prehistoric sites in northeastern China. Archaeological and anthropological study indicates that the epidemic happened quickly enough that there was no time for proper burials, and the site was not inhabited again. 

Before the discovery of Hamin Mangha, another prehistoric mass burial that dates to roughly the same time period was found at a site called Miaozigou, in northeastern China. Together, these discoveries suggest that an epidemic ravaged the entire region. 

430 B.C.: Athens

The earliest recorded pandemic happened during the Peloponnesian War. After the disease passed through Libya, Ethiopia and Egypt, it crossed the Athenian walls as the Spartans laid siege. As much as two-thirds of the population died.

The symptoms included fever, thirst, bloody throat and tongue, red skin and lesions. The disease, suspected to have been typhoid fever, weakened the Athenians significantly and was a significant factor in their defeat by the Spartans.

165 A.D.: Antonine Plague

The Antonine plague was possibly an early appearance of smallpox that began with the Huns. The Huns then infected the Germans, who passed it to the Romans and then returning troops spread it throughout the Roman empire. Symptoms included fever, sore throat, diarrhea and, if the patient lived long enough, pus-filled sores. This plague continued until about 180 A.D., claiming Emperor Marcus Aurelius as one of its victims.

250 A.D.: Cyprian Plague

Named after the first known victim, the Christian bishop of Carthage, the Cyprian plague entailed diarrhea, vomiting, throat ulcers, fever and gangrenous hands and feet.

City dwellers fled to the country to escape infection but instead spread the disease further. Possibly starting in Ethiopia, it passed through Northern Africa, into Rome, then onto Egypt and northward.

There were recurring outbreaks over the next three centuries. In 444 A.D., it hit Britain and obstructed defense efforts against the Picts and the Scots, causing the British to seek help from the Saxons, who would soon control the island.

541 A.D.: Justinian Plague

First appearing in Egypt, the Justinian plague spread through Palestine and the Byzantine Empire, and then throughout the Mediterranean.

The plague changed the course of the empire, squelching Emperor Justinian’s plans to bring the Roman Empire back together and causing massive economic struggle. It is also credited with creating an apocalyptic atmosphere that spurred the rapid spread of Christianity.

Recurrences over the next two centuries eventually killed about 50 million people, 26 percent of the world population. It is believed to be the first significant appearance of the bubonic plague, which features enlarged lymphatic gland and is carried by rats and spread by fleas.

11th Century: Leprosy

Though it had been around for ages, leprosy grew into a pandemic in Europe in the Middle Ages, resulting in the building of numerous leprosy-focused hospitals to accommodate the vast number of victims.

A slow-developing bacterial disease that causes sores and deformities, leprosy was believed to be a punishment from God that ran in families. This belief led to moral judgments and ostracization of victims. Now known as Hansen’s disease, it still afflicts tens of thousands of people a year and can be fatal if not treated with antibiotics.

1350: The Black Death

Responsible for the death of one-third of the world population, this second large outbreak of the bubonic plague possibly started in Asia and moved west in caravans. Entering through Sicily in 1347 A.D. when plague sufferers arrived in the port of Messina, it spread throughout Europe rapidly. Dead bodies became so prevalent that many remained rotting on the ground and created a constant stench in cities.

England and France were so incapacitated by the plague that the countries called a truce to their war. The British feudal system collapsed when the plague changed economic circumstances and demographics. Ravaging populations in Greenland, Vikings lost the strength to wage battle against native populations, and their exploration of North America halted.

1492: The Columbian Exchange

Following the arrival of the Spanish in the Caribbean, diseases such as smallpox, measles and bubonic plague were passed along to the native populations by the Europeans. With no previous exposure, these diseases devastated indigenous people, with as many as 90 percent dying throughout the north and south continents.

Upon arrival on the island of Hispaniola, Christopher Columbus encountered the Taino people, population 60,000. By 1548, the population stood at less than 500. This scenario repeated itself throughout the Americas.

In 1520, the Aztec Empire was destroyed by a smallpox infection. The disease killed many of its victims and incapacitated others. It weakened the population so they were unable to resist Spanish colonizers and left farmers unable to produce needed crops.

Research in 2019 even concluded that the deaths of some 56 million Native Americans in the 16th and 17th centuries, largely through disease, may have altered Earth’s climate as vegetation growth on previously tilled land drew more CO2 from the atmosphere and caused a cooling event.

1665: The Great Plague of London

In another devastating appearance, the bubonic plague led to the deaths of 20 percent of London’s population. As human death tolls mounted and mass graves appeared, hundreds of thousands of cats and dogs were slaughtered as the possible cause and the disease spread through ports along the Thames. The worst of the outbreak tapered off in the fall of 1666, around the same time as another destructive event—the Great Fire of London.

1720-1723: GREAT PLAGUE OF MARSEILLE

Historical records say that the Great Plague of Marseille started when a ship called “Grand-Saint-Antoine” docked in Marseille, France, carrying a cargo of goods from the eastern Mediterranean. Although the ship was quarantined, plague still got into the city, likely through fleas on plague-infected rodents. 

Plague spread quickly and, over the next three years, as many as 100,000 people may have died in Marseille and surrounding areas. It’s estimated that up to 30% of the population of Marseille may have perished. 

 1770-1772: RUSSIAN PLAGUE

In plague-ravaged Moscow, the terror of quarantined citizens erupted into violence. Riots spread through the city and culminated in the murder of Archbishop Ambrosius, who was encouraging crowds not to gather for worship.

The empress of Russia, Catherine II (also called Catherine the Great), was so desperate to contain the plague and restore public order that she issued a hasty decree ordering that all factories be moved from Moscow. By the time the plague ended, as many as 100,000 people may have died. Even after the plague ended, Catherine struggled to restore order. In 1773, Yemelyan Pugachev, a man who claimed to be Peter III (Catherine’s executed husband), led an insurrection that resulted in the deaths of thousands more. 

1793:  PHILADELPHIA YELLOW FEVER EPIDEMIC

When yellow fever seized Philadelphia, the United States’ capital at the time, officials wrongly believed that slaves were immune. As a result, abolitionists called for people of African origin to be recruited to nurse the sick.

The disease is carried and transmitted by mosquitoes, which experienced a population boom during the particularly hot and humid summer weather in Philadelphia that year. It wasn’t until winter arrived — and the mosquitoes died out — that the epidemic finally stopped. By then, more than 5,000 people had died.

1817: First Cholera Pandemic

The first of seven cholera pandemics over the next 150 years, this wave of the small intestine infection originated in Russia, where one million people died. Spreading through feces-infected water and food, the bacterium was passed along to British soldiers who brought it to India where millions more died. The reach of the British Empire and its navy spread cholera to Spain, Africa, Indonesia, China, Japan, Italy, Germany and America, where it killed 150,000 people. A vaccine was created in 1885, but pandemics continued.

1855: The Third Plague Pandemic

Starting in China and moving to India and Hong Kong, the bubonic plague claimed 15 million victims. Initially spread by fleas during a mining boom in Yunnan, the plague is considered a factor in the Parthay rebellion and the Taiping rebellion. India faced the most substantial casualties, and the epidemic was used as an excuse for repressive policies that sparked some revolt against the British. The pandemic was considered active until 1960 when cases dropped below a couple hundred.

1875: Fiji Measles Pandemic

After Fiji ceded to the British Empire, a royal party visited Australia as a gift from Queen Victoria. Arriving during a measles outbreak, the royal party brought the disease back to their island, and it was spread further by the tribal heads and police who met with them upon their return.

Spreading quickly, the island was littered with corpses that were scavenged by wild animals, and entire villages died and were burned down, sometimes with the sick trapped inside the fires. One-third of Fiji’s population, a total of 40,000 people, died.

1889: Russian Flu

The first significant flu pandemic started in Siberia and Kazakhstan, traveled to Moscow, and made its way into Finland and then Poland, where it moved into the rest of Europe. By the following year, it had crossed the ocean into North America and Africa. By the end of 1890, 360,000 had died.

1889-1890: Influenza Pandemic

Influenza remains a deadly disease that has caused previous pandemics and has the potential to cause future ones as well (Najera speculates the next flu pandemic will happen “sooner rather than later”).

In the modern industrial age, new transport links made it easier for influenza viruses to wreak havoc. In just a few months, the disease spanned the globe, killing 1 million people. It took just five weeks for the epidemic to reach peak mortality.

The earliest cases were reported in Russia. The virus spread rapidly throughout St. Petersburg before it quickly made its way throughout Europe and the rest of the world, despite the fact that air travel didn’t exist yet. 

1900: Rabies 

Rabies has played a large role in American film and literature—think Old Yeller, To Kill a Mockingbird and Their Eyes Were Watching God. But the deadly disease, which causes erratic behavior, is no longer a major threat in the United States because of vaccines.

In this case, most of the vaccines that have helped save human lives aren’t used on humans—they’re used on other animals that can carry the disease and infect humans by biting them. State rabies programs have guidelines for vaccinating pets and wildlife and tracking animals that might have rabies. Any human who is bitten by an animal, regardless of whether the animal has been vaccinated, must go to a doctor or hospital to receive a rabies vaccine.

1918: Spanish Flu

The avian-borne flu that resulted in 50 million deaths worldwide, the 1918 flu was first observed in Europe, the United States and parts of Asia before swiftly spreading around the world. At the time, there were no effective drugs or vaccines to treat this killer flu strain. Wire service reports of a flu outbreak in Madrid in the spring of 1918 led to the pandemic being called the “Spanish flu.”

By October, hundreds of thousands of Americans died and body storage scarcity hit crisis level. But the flu threat disappeared in the summer of 1919 when most of the infected had either developed immunities or died.

1916: American Polio Epidemic

Polio was once one of the most feared childhood diseases in the U.S. The viral infection can cause temporary or permanent paralysis, as it did with wheelchair-user Franklin D. Roosevelt. This paralysis could stop a person’s body from breathing on its own, which is why so many infected people had to be placed in an “iron lung.” By the late 1940s, it was disabling more than 35,000 Americans each year. The number of U.S. polio cases peaked in 1952, when it caused 57,879 infections and 3,145 deaths.

During the 1954 trials for Jonas Salk’s polio vaccine, parents flocked to sign their children up to get the shot. As a result, 623,972 children received the vaccine or a placebo. The trials showed the vaccine was 80 to 90 percent effective at preventing polio. Thanks to the continued vaccination of children through today, no polio cases have originated in the United States since 1979. However, polio has not been eradicated, and remains a health threat in Afghanistan and Pakistan.

1957: Asian flu

Starting in Hong Kong and spreading throughout China and then into the United States, the Asian flu became widespread in England where, over six months, 14,000 people died. A second wave followed in early 1958, causing an estimated total of about 1.1 million deaths globally, with 116,000 deaths in the United States alone. A vaccine was developed, effectively containing the pandemic.

1981: HIV/AIDS

First identified in 1981, AIDS destroys a person’s immune system, resulting in eventual death by diseases that the body would usually fight off. Those infected by the HIV virus encounter fever, headache, and enlarged lymph nodes upon infection. When symptoms subside, carriers become highly infectious through blood and genital fluid, and the disease destroys t-cells.

AIDS was first observed in American gay communities but is believed to have developed from a chimpanzee virus from West Africa in the 1920s. The disease, which spreads through certain body fluids, moved to Haiti in the 1960s, and then New York and San Francisco in the 1970s.

Treatments have been developed to slow the progress of the disease, but 35 million people worldwide have died of AIDS since its discovery, and a cure is yet to be found.

2003: SARS

First identified in 2003 after several months of cases, Severe Acute Respiratory Syndrome is believed to have possibly started with bats, spread to cats and then to humans in China, followed by 26 other countries, infecting 8,096 people, with 774 deaths.

SARS is characterized by respiratory problems, dry cough, fever and head and body aches and is spread through respiratory droplets from coughs and sneezes.

Quarantine efforts proved effective and by July, the virus was contained and hasn’t reappeared since. China was criticized for trying to suppress information about the virus at the beginning of the outbreak.

SARS was seen by global health professionals as a wake-up call to improve outbreak responses, and lessons from the pandemic were used to keep diseases like H1N1, Ebola and Zika under control.

2009-2010: H1N1 SWINE FLU PANDEMIC

The 2009 swine flu pandemic was caused by a new strain of H1N1 that originated in Mexico in the spring of 2009 before spreading to the rest of the world. In one year, the virus infected as many as 1.4 billion people across the globe and killed between 151,700 and 575,400 people, according to the CDC.

The 2009 flu pandemic primarily affected children and young adults, and 80% of the deaths were in people younger than 65, the CDC reported. That was unusual, considering that most strains of flu viruses, including those that cause seasonal flu, cause the highest percentage of deaths in people ages 65 and older.

But in the case of the swine flu, older people seemed to have already built up enough immunity to the group of viruses that H1N1 belongs to, so weren’t affected as much. A vaccine for the H1N1 virus that caused the swine flu is now included in the annual flu vaccine. 

2014-2016: WEST AFRICAN EBOLA EPIDEMIC

Ebola ravaged West Africa between 2014 and 2016, with 28,600 reported cases and 11,325 deaths. The first case to be reported was in Guinea in December 2013, then the disease quickly spread to Liberia and Sierra Leone. The bulk of the cases and deaths occurred in those three countries. A smaller number of cases occurred in Nigeria, Mali, Senegal, the United States and Europe, the Centers for Disease Control and Prevention reported. 

There is no cure for Ebola, although efforts at finding a vaccine are ongoing. The first known cases of Ebola occurred in Sudan and the Democratic Republic of Congo in 1976, and the virus may have originated in bats. 

2015- Present Day: ZIKA VIRUS EPIDEMIC

The impact of the recent Zika epidemic in South America and Central America won’t be known for several years. In the meantime, scientists face a race against time to bring the virus under control. The Zika virus is usually spread through mosquitoes of the Aedes genus, although it can also be sexually transmitted in humans. 

While Zika is usually not harmful to adults or children, it can attack infants who are still in the womb and cause birth defects. The type of mosquitoes that carry Zika flourish best in warm, humid climates, making South America, Central America and parts of the southern United States prime areas for the virus to flourish. 

2019: COVID-19

On March 11, 2020, the World Health Organization announced that the COVID-19 virus was officially a pandemic after barreling through 114 countries in three months and infecting over 118,000 people. And the spread wasn’t anywhere near finished.

COVID-19 is caused by a novel coronavirus—a new coronavirus strain that has not been previously found in people. Symptoms include respiratory problems, fever and cough, and can lead to pneumonia and death. Like SARS, it’s spread through droplets from sneezes.

The first reported case in China appeared November 17, 2019, in the Hubei Province, but went unrecognized. Eight more cases appeared in December with researchers pointing to an unknown virus. 

Many learned about COVID-19 when ophthalmologist Dr. Li Wenliang defied government orders and released safety information to other doctors. The following day, China informed WHO and charged Li with a crime. Li died from COVID-19 just over a month later.

Without a vaccine available, the virus spread beyond Chinese borders to nearly every country in the world. By December 2020, it had infected more than 75 million people and led to more than 1.6 million deaths worldwide. The number of new cases was growing faster than ever, with more than 500,000 reported each day on average.

Many people are against vaccinations, and that is their right to feel this way. However, I can’t but feel that they are acting out ignorance. Widespread vaccination has helped decrease or virtually eliminate many dangerous and deadly diseases in the United States. Yet because vaccines have been so effective at removing threats, it’s sometimes difficult to appreciate just how significant they have been to public health.

The Future of Pandemics

The ongoing global HIV pandemic, the recent outbreaks of pathogens such as SARS and the H5N1 influenza virus, as well as the current H1N1 influenza pandemic, the global consequences of which are still to be determined, demonstrate our continued vulnerability to emerging infectious diseases. The most recent example, H1N1 influenza, and its dramatic spread also reminds us that we have entered into a new age of global pandemics, largely because of the rapidity with which newly emergent pathogens are capable of being transmitted around the world. Because of our continued vulnerability and the challenges that global travel poses to pandemic control, it is now more important than ever that we identify emerging infectious diseases early. Although it is still difficult to predict the agent that will pose the next pandemic threat, when it will occur or where it will begin, it will likely be the result of cross-species transmission from animals to humans. This likelihood argues in favor of developing a system aimed at detecting the transmission of potentially pathogenic agents from animals to humans early in the zoonotic disease emergence process and identifying ways by which we can diminish the risk of transmission, especially in populations that are highly exposed to animals and their potentially zoonotic agents.

The previous paragraph was taken from “The Origin and Prevention of Pandemics” by JM Hughes.

My intention in this chapter is to discuss the natural progression of a viral epidemic. Some viruses just disappear on their own. Some viruses like Small pox and polio are eradicated by vaccines. Other viruses like the flu become endemic and never truly go away. We simply learn to live with them. The vast majority of people who die from the flu are either very young children who haven’t developed a more mature immune system or the elderly who have weakened immune systems or people that are in poor health and malnourished. The vast majority of viral pandemics mutate to less deadly forms, like the original SARS virus. It is postulated that the COVID-19 virus will become less deadly and will evolve into an endemic state. In which case an acceptable number of deaths will occur each year and we will have the option of getting the vaccination like we do the flu vaccine every year. We are already seeing this take place as exhibited by the most recent mutation to the Omicron variant. Evolution is survival of the fittest. We have evolved to the top of the food chain, so our only enemy is either ourselves or infectious agents.

Man is without a doubt the apex predator in this planet, with technology we can extinguish any life form or species, and we have driven countless species into extinction through our careless predation. However, we have been unable to eradicate viruses. we have managed to eliminate a few with vaccinations, but for the most part the vast majority of them still exist and routinely kick our asses. I believe viruses are the worlds way of population control. It seems the greater the incursion into nature, the harder nature fights back. It is humbling to think that something so small can bring civilization to its knees.

Viruses are self limiting, they can only produce and exist in a host. The definition of a virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. They are also called obligate parasites for the same reason. As such they are simplistic – so simple , in fact, that they don’t satisfy all the criteria to be considered alive. Viruses cannot synthesize adenosine triphosphate, a critical molecule used for carrying energy. They likewise do not posses the molecular equipment to perform translation, the process that uses information from the genetic code called RNA to synthesize the proteins, which are the workhorses of cellular life. Viruses infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. If the host species are totally killed off, the virus dies with it. So for a virus to proliferate, it has to be easily spread and to also not be so deadly that it kills its host before it spreads. It seems viruses have a better understanding of nature than do people. People have been compared to a cancer, because a cancer has not shut off switch. Healthy cells stop growing when they reach a boundary, while cancers spread uncontrollably. Humans behave in much the same way. So the question is who is the apex species in this planet?

The following information is provided by the web site the Chathamhouse.org.

It is impossible to predict when the next pandemic will occur as they are random events. They can begin anywhere in the world where animals and humans are in close proximity as pandemics most often originate when a pathogen transfers from an animal in which it lives to a human never before infected with that pathogen.

When emergence in humans occurs, one of three outcomes are the result: the pathogen causes an illness in a single person, as with rabies; it causes a wider outbreak, such as the Ebola virus disease in the Democratic Republic of Congo in 2018 and 2020; or it causes a pandemic with the potential to become endemic, such as HIV.

The large influenza pandemic in 1918 is a major historical point of reference but there have been several less lethal influenza pandemics since then. Some experts call HIV a pandemic which has become endemic.

Infectious disease outbreaks are most likely to occur when a series of risk factors happen together. An El Niño weather event in 1998 caused flooding in Kenya, Somalia, Sudan, and Tanzania which meant cattle and humans were forced to live closer together on the remaining dry land. This increased the risk of cross-species pathogen transmission. Due to a shortage of vaccines, the cattle were unvaccinated against the Rift Valley Fever virus, a common infection among ruminant animals in the region.

The flooding created more breeding sites for mosquitoes, leading to a rapid increase in the mosquito population. Mosquitoes are one means of transmission of the Rift Valley Fever virus from animals to humans, and from human to human. This facilitated emergence of the virus in human populations which was then transmitted from human to human.

Alignment of all these risk factors resulted in a major outbreak of Rift Valley Fever among the region’s human population.

Where could the next outbreaks occur?

Efforts have been made to predict where pandemics may originate by identifying sites of emergence in the past, such as mapping all known emerging-infection incidents from the 1940s to the early 2000s and predicting that emergence would occur at one of those sites. But emergence is a random event both in time and place and mapping has not been a reliable predictor.

A new pandemic could begin anywhere where there is close interaction of people and either domesticated or wild animals

Influenza pandemics historically emerged in southern China so that area was the focus of attention as a possible source of new strains of the influenza virus. But the 2009 H1N1 ‘swine flu’ pandemic is thought to have originated in Mexico and/or the southern US rather than in China.

Even if there was a genetic-sequencing library of all organisms carried by wild animals linked to the animals in which they are found, such a database would be difficult to keep updated. At best, it could give an idea of the origin of a newly identified pathogen but scientists cannot predict an outbreak using such databases. A new pandemic could begin anywhere where there is close interaction of people and either domesticated or wild animals.

What could be the next pandemic?

There are a few known pathogens – either viruses or bacteria – that can cause pandemic- or epidemic-prone diseases.

Most influenza viruses originate in wild waterfowl. The H1N1 swine flu virus had its origins in bird populations thought to have then transferred infection to pigs where it mutated in such a way that it could transmit easily from human to human – once humans had been infected directly by pigs.

Respiratory infections represent one of the highest risks of an epidemic or pandemic after emergence and human-to-human spread, as infected humans often create aerosols when they cough, sneeze, or speak loudly.

Influenza

The influenza virus is an unstable virus which originates in wild waterfowl which transmit infection to domestic birds and poultry, and they then pass it on to animals and/or humans. Sometimes, the influenza virus mutates into a form which can spread easily in humans. In those circumstances a pandemic can occur.

Before the COVID-19 pandemic, advance plans in most countries anticipated a pandemic strain of influenza virus. But countries in Asia which had experienced outbreaks of SARS coronavirus in 2003 tended also to take coronaviruses into consideration.

Coronavirus

There have been three outbreaks caused by coronaviruses in humans during the past 20 years. Each originated among wild animals and one of these viruses – SARS-CoV-2 – is the cause of the COVID-19 pandemic.

In addition, there are four coronavirus strains that are endemic in humans, causing the common cold. These are thought to have emerged from animals at some time in the past. SARS-CoV-2 will most likely become the fifth endemic strain.

Ebola

Highly lethal infections with a short incubation period, such as the Ebola virus disease, are much less likely to become pandemic.

Highly lethal infections with a short incubation period, such as the Ebola virus disease, are much less likely to become pandemic

They cause severe illness early in infection that incapacitates and kills those infected, giving the virus little time to be transmitted to others.  

By contrast, HIV has a long period when it does not cause signs and symptoms but can transmit from human to human, making it well-adapted to becoming endemic.

SARS-CoV-2 has a relatively low level of mortality compared to the Ebola virus. In the future it is possible, but not predictable, that a more lethal coronavirus strain could emerge.

What role does climate change play in the next pandemic?

The leading causes of climate change can also increase the risk of pandemics occurring. Deforestation, urbanization, and the enormous livestock husbandry required for a growing meat-production industry all bring more and more animals into closer contact with humans. This in turn increases the likelihood of pathogens ‘jumping’ from animal to human.

It is generally accepted there will be another pandemic and that, through many of the same activities that fuel climate change, humans are giving pandemics more opportunities to occur.

Only by maintaining a healthy environment and animal populations can we hope to protect and ensure the security of human health

That is why a ‘one health’ approach is so important – the animal health, human health, and environmental sectors must work together to rapidly detect and respond to pandemic risks.

Pandemic prevention and preparedness must be considered in the context of the ecosystem and animal health as much as in that of human health.

Only by maintaining a healthy environment and animal populations can we hope to protect and ensure the security of human health.

How do we monitor for the next outbreak?

The most important task for all countries is to strengthen their capacity to identify and respond to outbreaks where and when they occur. This includes genetic sequencing of pathogens and sharing of sequence data in global databases.

To ensure the best possible health security for the human population, industrialized nations should support lower- and middle-income countries as they strengthen their public health capacity.

The COVID-19 pandemic exposed weaknesses in laboratory capacity in many parts of the world. A major effort by the World Health Organization (WHO) and partners is helping strengthen that capacity, essential for detecting the spread of future pathogens.

To do that requires more than a one-size-fits-all approach – laboratories can only be sustained if they are adapted to suit the environments and societies hosting them.

Another major factor in monitoring is the need to shift the emphasis from detecting pathogens in humans to detecting them in animal populations early and preventing them from becoming established long before they spread to humans.

What is the current pandemic prevention strategy?

Individual countries have their own plans for managing pandemics. There is also a global governance mechanism – the International Health Regulations (IHR) – which attempts to bring countries together with common strategies and policies during major outbreaks and pandemics. The regulations are currently being assessed to identify weaknesses exposed during the COVID-19 pandemic.

At the same time, efforts are underway to develop a pandemic preparedness treaty, which is considered by the World Health Assembly (WHA) to be especially urgent as the COVID-19 pandemic exposed serious deficiencies in the world’s ability to respond.

In December 2021, WHA members agreed to begin drafting an international instrument to strengthen pandemic prevention, preparedness, and response.

It is vital to learn from history. After the 2003 SARS outbreak, studies of one farm selling to wild animal markets in China showed 80 per cent of its animals had antibody evidence of prior coronavirus infection. And 13 per cent of the workers in the market had antibody evidence, compared to 1-3 per cent of the population served by the market.

These studies provide clear lessons about the need to improve education in the farming and market industry, to develop vaccines for animals and humans, and to protect animal husbandry from potential carriers of coronaviruses such as bats. But the policy response was to ban the selling of wild animals in Chinese markets, potentially driving the trade underground and increasing the risks of emergence.

There is also a need to establish global standards for maximum-security laboratories which handle dangerous pathogens, whether operated by public institutes or by private industry.

The last recorded human cases of smallpox were caused by a laboratory accident in the UK, and the last human infections of SARS were the result of laboratory accidents in China, Singapore, and Taiwan. The origin of the COVID-19 pandemic is uncertain but one hypothesis is it was caused by a leak from a laboratory working with coronaviruses.

There is therefore a need for a robust consensus on biosafety in laboratories – one developed by scientists to ensure they buy into the concept and countries understand their responsibilities for safe laboratory operations. This is tremendously challenging because different countries have different needs.

How do we prepare for the next pandemic?

The success of any preparations for the next pandemic relies on the strength of countries’ systems for detecting and responding to outbreaks. But at the same time countries must better cooperate to ensure more equitable distribution of the tools needed for preparedness and response.

COVID-19 saw wealthy nations prioritize their own populations over a more equitable global response, arguably prolonging and extending the effects of the pandemic in the process. Some developing nations struggled to access the diagnostics, vaccines, and treatments they needed to respond effectively.

The ACT-A (Access to COVID Tools Accelerator) was set up by WHO and partner organizations early in the COVID-19 pandemic. The intention was to more equitably distribute COVID diagnostics, treatments, and vaccines and to help countries use them efficiently. COVAX, part of the ACT-A, was created to ensure that all nations could access vaccines at a favourable cost regardless of their wealth.

But by the time the ACT-A had been established, many countries – including the UK and the US – had pre-purchased billions of dollars-worth of vaccines at considerable risk, hoping that this upfront funding would enable vaccines to be developed, licensed, and produced rapidly.

Arguably, if it had been established before these pre-purchases occurred, the ACT-A mechanism could have better realized the vision of providing an equitable marketplace for all countries.