Pandemic

epidemic of infectious disease that has spread across a large region with global health impact

A pandemic (from Greek πᾶν, pan, "all" and δῆμος, demos, "people") is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of people.

Quotes

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The truth of the matter is that pandemics always end. And to date vaccines have never played a significant role in ending them. ~ Helen Branswell
  • The truth of the matter is that pandemics always end. And to date vaccines have never played a significant role in ending them. (That doesn’t mean vaccines aren’t playing a critical role this time. Far fewer people will die from Covid-19 because of them.)
    But there were no flu vaccines in 1918, when the world didn’t yet know that the great influenza was caused by a virus, H1N1. In 1957, when the H2N2 pandemic swept the world, flu vaccine was mainly a tool of the military. In the pandemic of 1968, which brought us H3N2, the United States produced nearly 22 million doses of vaccine, but by the time it was ready the worst of the pandemic had passed, and demand subsided. That “too little and too late” phenomenon played out again in 2009, when the world finally had the capacity to make hundreds of millions of doses of H1N1 vaccine; some countries canceled large portions of their orders because they ended up not needing them.
    How did those pandemics end? The viruses didn’t go away; a descendent of the Spanish flu virus, the modern H1N1, circulates to this day, as does H3N2. Humans didn’t develop herd immunity to them, either. That’s a phenomenon by which a pathogen stops spreading because so many people are protected against it, because they’ve already been infected or vaccinated.
    Instead, the viruses that caused these pandemics underwent a transition. Or more to the point, we did. Our immune systems learned enough about them to fend off the deadliest manifestations of infection, at least most of the time. Humans and viruses reached an immunological détente. Instead of causing tsunamis of devastating illness, over time the viruses came to trigger small surges of milder illness. Pandemic flu became seasonal flu.
  • There was a global pandemic just ninety-five years ago [in 1918]—the Spanish flu pandemic, which is now estimated to have killed up to 100 million people. And that’s before one of our more questionable innovations—budget airlines—were invented. The combination of millions of people traveling around the world every day, plus millions more people living in extremely close proximity to pigs and poultry—often in the same room, making a new virus jumping the species barrier more likely—means we are increasing, significantly, the probability of a new global pandemic. So no wonder then that epidemiologists increasingly agree that a new global pandemic is now a matter of “when” not “if.”
    • Stephen Emmott, 10 Billion (2013)
  • In his famous novel, The Plague, Albert Camus discussed the idea of plague as being akin to a despotic rule under which everyone, starting from the warden to the humblest delinquent, was under a life sentence. This insight is true for any pandemic including COVID–19 because the infection spreading microbe infects both rich and poor people alike. However, the literature on the motif of plagues and pandemics expounds one naked truth: that a pandemic thrives on human inequities and it is inextricable from the society, economy, knowledge, and politics of human existence.
  • The connection between epidemics and pandemics and the growth of the modern state is clear. As early as the fifteenth century, in response to the plague, Italian city states formed state-sponsored boards of health. The cholera pandemics of the nineteenth century led to nationwide efforts at quarantine—efforts that could only be carried off by a central state. Measures such as compulsory vaccination also demonstrated this connection.
  • The R0 values have important implications for disease control. R0 magnitude indicates the level of mitigation efforts needed to bring an epidemic under control. Mitigation reduces the effective transmission coefficient, now called Re. Re needs to be reduced to less than 1 to ensure cessation of an epidemic, which can be done by rapid case identification, quarantine measures, and physical distancing to prevent secondary transmissions. For childhood diseases such as measles, the cessation of epidemic spread was achieved with an effective vaccine. However, a vaccine has never been a major tool for control of pandemics because they either occurred before the era of modern vaccines or, as in 2009, the vaccine became available only after the first waves had already occurred.
 
[A]ny new pandemic influenza vaccine will take about 4-6 months to produce in large quantity. For other newly emerging threats without licensed vaccines, such as SARS, Marburg virus, Nipah virus, and the like, the time required to develop and produce a safe, effective vaccine is unknown and would depend on the nature of the threat and the state of current vaccine research for that threat. In almost all cases, several months would be needed to respond with the first doses of vaccines. Until a safe, effective vaccine were ready, other public health and medical measures, such as social distancing, quarantine, and use of anti-viral medications, would need to be employed to try to limit disease spread. ~ Histoyofvaccines.org
  • Vaccination will likely be part of a multi-faceted public health response to the future emergence of a pandemic illness. In addition to other measures designed to respond to and control a pandemic, such as surveillance, communication plans, quarantine, and disease treatment, deployment of effective vaccines has the potential to protect lives and limit disease spread. Not all disease threats, however, have a corresponding vaccine, and for those that do, there are significant challenges to their successful use in a pandemic.
  • A challenge in responding to pandemic diseases is that vaccines may not exist for them or that, especially in the case of influenza viruses, existing vaccines may not be effective against them. Though production methods and infrastructure for influenza vaccines are well established, each new influenza strain requires a new vaccine. Thus, any new pandemic influenza vaccine will take about 4-6 months to produce in large quantity. For other newly emerging threats without licensed vaccines, such as SARS, Marburg virus, Nipah virus, and the like, the time required to develop and produce a safe, effective vaccine is unknown and would depend on the nature of the threat and the state of current vaccine research for that threat. In almost all cases, several months would be needed to respond with the first doses of vaccines. Until a safe, effective vaccine were ready, other public health and medical measures, such as social distancing, quarantine, and use of anti-viral medications, would need to be employed to try to limit disease spread.
  • In all pandemic situations in which a vaccine is available or potentially available, a large supply of vaccine would be necessary and would be needed quickly. Currently, the U.S. Strategic National Stockpile includes several types of influenza vaccines, including an H5N1 vaccine. The stockpile also holds millions of doses of other vaccines, antibodies, antiviral medications and other medical supplies. Should any of these stockpiled vaccines directly relate to an emerging pandemic, they would be deployed. But chances are that an emerging pandemic illness will require a new vaccine.
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