They occur about every hundred years on average. In the past 2,000 years maybe 400 million people have been killed by them.

In 2005 President Bush predicted a pandemic - https://www.youtube.com/watch?v=spcj6KUr4aA

2008 - "the likelihood of a flu pandemic in the next 50 years approaches 100%" - a review of 'Global Catastrophes and Trends' - Vaclav Smil https://vaclavsmil.com/wp-content/uploads/docs/smil-bookreview-global-catastrophes20080000-predicting-the-future.pdf

In 2014 President Obama predicted a pandemic - https://www.youtube.com/watch?v=pBVAnaHxHbM

2012 - "David Quammen speculates that there would indeed be a new disease, likely from the coronavirus family, coming out of a bat, and it would likely emerge in or around a wet market in China." - 'Spillover: Animal Infections and the Next Human Pandemic' - https://thebulletin.org/2020/06/how-it-feels-to-predict-a-pandemic-interview-with-david-quammen-author-of-spillover/

2017 - "a dismal introduction on the threat of epidemics" 'Deadliest Enemy: Our War Against Killer Germs' - Michael T. Osterholm and Mark Olshaker https://www.publishersweekly.com/9780316343695

2019 - "We assess that the United States and the world will remain vulnerable to the next flu pandemic or large-scale outbreak of a contagious disease that could lead to massive rates of death and disability, severely affect the world economy, strain international resources, and increase calls on the United States for support" WORLDWIDE THREAT ASSESSMENT of the US INTELLIGENCE COMMUNITY - https://www.odni.gov/files/ODNI/documents/2019-ATA-SFR---SSCI.pdf

COVID won't be the last one.