{"id":3787,"date":"2023-06-06T20:32:24","date_gmt":"2023-06-07T01:32:24","guid":{"rendered":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/?p=3787"},"modified":"2023-06-06T20:32:27","modified_gmt":"2023-06-07T01:32:27","slug":"the-deadliest-viruses-in-human-history-from-covid-to-smallpox","status":"publish","type":"post","link":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/2023\/06\/06\/the-deadliest-viruses-in-human-history-from-covid-to-smallpox\/","title":{"rendered":"The deadliest viruses in human history, from COVID to smallpox"},"content":{"rendered":"
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PopSci<\/a> Deadly viral pathogens include rabies, which is fatal without swift treatment, and the flu, which has a huge global toll.<\/strong> Over the first two years of the COVID-19 pandemic, the coronavirus directly or indirectly killed about\u00a015 million people worldwide<\/a>, according to estimates from the World Health Organization. In the United States, more people died in 2020 and 2021 than\u00a0during the 1918 influenza pandemic<\/a>, which was widely called the most deadly in recorded history.\u00a0 The word \u201cdeadly\u201d certainly applies to the virus that causes COVID-19. And yet, epidemiologists hesitate to give SARS-CoV-2 the superlative of\u00a0deadliest<\/em>\u00a0virus in human history. To them, the raw number of mortalities caused by a given virus doesn\u2019t always paint the full picture of a pathogen\u2019s danger\u2014especially when comparing viral outbreaks across time. <\/p>\n\n\n\n

Defining the deadliest virus<\/h2>\n\n\n\n

Instead of just looking at tallied mortalities, epidemiologists use a metric called the \u201ccase fatality rate\u201d<\/a> or \u201ccase fatality ratio\u201d as a measure of how likely a virus is to be lethal. Essentially, it\u2019s the proportion of infected people who end up dying, and therefore represents the likelihood that an infection will end in death. <\/p>\n\n\n\n

Using the \u201ccase fatality rate\u201d metric to determine what virus is the deadliest, rabies would likely come out on top. That\u2019s because, if an infection becomes symptomatic, rabies is fatal to humans<\/a> in more than 99 percent of cases. Globally, approximately 59,000 people die from rabies every year. Very few of those deaths\u2014an average of two in the US\u2014occur in the developed world because of rabies vaccines for household pets and swift medical interventions after bites.<\/p>\n\n\n\n

But \u201ca virus doesn\u2019t have to have a very high case fatality ratio to cause a tremendous amount of death and disruption,\u201d Nuzzo says. \u201cIt\u2019s more about looking at the environments in which the viruses are spreading, and our social and human vulnerabilities to it.\u201d <\/p>\n\n\n\n

Raw mortality numbers have to be taken in the context of the world\u2019s total population, says\u00a0Jennifer Nuzzo<\/a>, professor of epidemiology and director of the Pandemic Center at Brown University School of Public Health. \u201cA lot of people talk about how COVID deaths eclipsed what we saw in 1918,\u201d she says. \u201cIt\u2019s really important to remember that the population of 1918 was a fraction of what it is today.\u201d In that context, the flu of 1918 rises back up in the ranks in terms of deadliness.<\/p>\n\n\n\n

A virus with a lower case fatality rate can kill more people if it\u2019s highly transmissible, with a long period of time before severe or obvious symptoms set in. This allows an infected person to expose many others. That\u2019s why SARS-CoV-2 caused such a rapid and devastating outbreak around the globe. It\u2019s easily transmitted via airborne droplets<\/a>, and doesn\u2019t always or immediately cause severe illness. <\/p>\n\n\n\n

Globalization sped it along, too. \u201cWhen a virus spreads at the pace of a human being walking, that\u2019s very different than when you can hop on an airplane and be anywhere in the world in 36 hours,\u201d Nuzzo says. <\/p>\n<\/div><\/div>","protected":false},"excerpt":{"rendered":"

PopSci Deadly viral pathogens include rabies, which is fatal without swift treatment, and the flu, which has a huge global toll. Over the first two years of the COVID-19 pandemic, the coronavirus directly or indirectly killed about\u00a015 million people worldwide, according to estimates from the World Health Organization. In the United States, more people died […]<\/p>\n","protected":false},"author":11,"featured_media":3788,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[21],"tags":[],"class_list":["post-3787","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-featured"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-content\/uploads\/2023\/06\/Screenshot-2023-06-06-at-21.31.51.png","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/posts\/3787","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/comments?post=3787"}],"version-history":[{"count":1,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/posts\/3787\/revisions"}],"predecessor-version":[{"id":3789,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/posts\/3787\/revisions\/3789"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/media\/3788"}],"wp:attachment":[{"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/media?parent=3787"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/categories?post=3787"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.unmc.edu\/healthsecurity\/transmission\/wp-json\/wp\/v2\/tags?post=3787"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}