The Difficulty of Predicting the Coronavirus Trajectory

How fast will the new coronavirus spread? Biostatisticians are trying to predict its pattern. Picture by Shutterstock.

There is currently a debate about the trajectory of the new coronavirus disease, now named COVID-19. Different models are predicting different outcomes and numbers provided by Chinese authorities seem to indicate a steep increase in cases.

A Wall Street Journal article from this week addresses fears about the rapid spread by quoting Mike Ryan, head of the WHO’s health emergencies program, who explained that the “outbreak’s general trajectory hasn’t changed, and the cases aren’t dramatically rising outside of China”. Additionally, the article quoted Ben Cowling, head of the epidemiology and biostatistics division at Hong Kong University’s School of Public Health. Professor Cowling noted that the newly reported cases are “probably a backlog of cases”.

I happened to interview Professor Cowling last year for my blog, discussing the importance of non-medical countermeasures during an epidemic (see: https://gordianknotbio.com/2018/11/02/a-conversation-about-pandemic-preparedness-part-1/#more-1668).

Professor Cowling’s statement is in line with the views of Michael Mina, an epidemiologist at Harvard’s T.H. Chan School of Public Health. In another WSJ article, Michael Mina stated that “there can never be any more new cases than there are tests per day”. He further clarified his position by saying that “to report 5,000 new cases one day and then 10,000 cases 3-5 days later requires a massive expansion of resources that just don’t exist”.

While these quotations alleviate some anxiety around this virus, the situation remains fluid and unpredictable. “We are in unknown territory…we don’t know what is going to happen” according to Marc Lipsitch, also an epidemiologist at the Harvard T.H. Chan School of Public Health.

“Rise in China Coronavirus Infections Raises Concerns About Epidemic’s Scope”, by Stu Woo, Wall Street Journal, February 15-16, 2020
https://www.wsj.com/articles/1-716-chinese-health-workers-infected-by-coronavirus-six-health-workers-dead-11581668705