--- description: A new study estimates coronavirus COVID-19's incubation period at five days, meaning it takes five days to show coronavirus symptoms. title: It Takes About 5 Days for Sick People to Show Coronavirus Symptoms image: https://static.time.com/v3/assets/bltea6093859af6183b/bltb961761d0f2d2a80/698a0b43e76ad222226375ab/coronavirus-incubation-period.jpg?branch=production&width=2400&quality=75&auto=webp&crop=16:9 ---  * [Health](/section/health/) ## Health Update your preferences in [Account Settings](/account/preferences/) Close * [COVID-19](/tag/covid-19/) ## COVID-19 Update your preferences in [Account Settings](/account/preferences/) Close # It Takes About 5 Days for Sick People to Show Coronavirus Symptoms, New Study Says ## Video: Some Patients With Coronavirus Only Show Mild Symptoms. Here's Why That's a Problem [Watch (HLS stream): Some Patients With Coronavirus Only Show Mild Symptoms. Here's Why That's a Problem](https://cdn.jwplayer.com/manifests/NG5CJgpl.m3u8) (0:38)  _Published 2020-01-28. As researchers fight to stop the spread of a novel coronavirus , they are facing a counter-intuitive problem: the symptoms can sometimes be so mild in patients that the virus is very difficult to detect._  by [Jamie Ducharme](/author/jamie-ducharme/)  ## Jamie Ducharme Update your preferences in [Account Settings](/account/preferences/) Close Ducharme is a contributor to TIME. Mar 9, 2020 9:00 PM CUT  People wear face masks as a precaution against coronavirus in Rome, Italy on March 6, 2020. People wear face masks as a precaution against coronavirus in Rome, Italy on March 6, 2020.Anadolu Agency via Getty Images—2020 Anadolu Agency  by [Jamie Ducharme](/author/jamie-ducharme/)  ## Jamie Ducharme Update your preferences in [Account Settings](/account/preferences/) Close Ducharme is a contributor to TIME. Mar 9, 2020 9:00 PM CUT Questions about coronavirus—how it behaves, [who it strikes](https://time.com/5794374/coronavirus-seniors/ "undefined"), and how bad it can get—are spreading almost as fast [as the virus itself](https://time.com/5783771/coronavirus-us-cases/ "undefined"). Among the most important questions to answer is how long it takes people who are infected by SARS-CoV-2, the virus that causes COVID-19, to show symptoms. Understanding that timeline, known as an incubation period, is crucial to developing effective disease containment and prevention measures. [A new study](https://annals.org/errors/404.aspx?aspxerrorpath=/aim/fullarticle/doi/10.7326/M20-0504 "undefined"), published Monday in the _Annals of Internal Medicine,_ offers a new estimate that is largely in keeping with [other](https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.5.2000062 "undefined") early [studies](https://www.ncbi.nlm.nih.gov/pubmed/32079150 "undefined") of the outbreak. The coronavirus’ median incubation period, the new paper says, appears to be about five days, with the vast majority of people developing symptoms within 12 days. Incubation numbers will “inevitably be refined as we get more information,” says study co-author Justin Lessler, an associate professor of infectious disease epidemiology at the Johns Hopkins Bloomberg School of Public Health, but having early insights is “important for thinking about controls such as quarantine and active monitoring.” The U.S. Centers for Disease Control and Prevention has been [isolating individuals](https://time.com/5796642/how-to-quarantine-yourself-coronavirus/ "undefined") suspected or confirmed to have COVID-19 for 14 days, working off the assumption that the disease’s average incubation period is roughly a week long—and thus, that almost everyone infected by the virus will show symptoms within a 14-day period. **_Sign up for our daily coronavirus newsletter by clicking_** [**_on this link._**](https://cloud.newsletters.time.com/coronavirus?source=article "undefined") While there have been [reports](https://jamanetwork.com/journals/jama/fullarticle/2762028?guestAccessKey=9e4e116a-7ab4-4a98-97b7-9b0bbedb5c6f&utm%5Fsource=For%5FThe%5FMedia&utm%5Fmedium=referral&utm%5Fcampaign=ftm%5Flinks&utm%5Fcontent=tfl&utm%5Fterm=022120 "undefined") of incubation periods longer than 14 days, the new study estimates that about 1% of every 10,000 patients would develop symptoms after being released from a two-week monitoring period. At this point in the outbreak, when there’s no longer a possibility [of entirely stopping](https://time.com/5797636/trump-botched-coronavirus-response/ "undefined") the spread of COVID-19 within the U.S., Lessler says public-health officials may have to live with that risk. “[Now that the virus is out](https://time.com/5796699/coronavirus-pandemics-containment-strategy/ "undefined") there in more places in the U.S., maybe just some risk mitigation and slowing things down is a better strategy” than making quarantine practices even more aggressive, Lessler says. “It’s not like quarantine doesn’t [have costs](https://time.com/5793629/coronavirus-quarantine-vacation-costs/ "undefined"), particularly if it’s a health care worker.” Lessler and his colleagues based their estimates on 181 confirmed COVID-19 cases reported by media outlets and public-health groups between Jan. 4 and Feb. 24., 2020\. Most cases were among people who had traveled to Wuhan, China, where the outbreak originated, and determining exactly when each person became ill required some educated guesswork. Whenever possible, researchers relied on a specific sequence of events—a particular interaction or activity that may have led to infection—to calculate the delay between exposure and symptom onset. Lessler emphasizes that it’s early days for crunching data about the outbreak—especially in the U.S., where large-scale testing is [only just beginning.](https://time.com/5793605/coronavirus-testing-united-states/ "undefined") But as more data about incubation period, mortality rates and other facets of the outbreak accumulate, doctors will have an increasingly solid idea of what they’re up against. **_Send any tips, leads, and stories to_** [**_virus@time.com_**](mailto:virus@time.com "undefined")**_._** ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/5797300/coronavirus-incubation-period/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/5797300/coronavirus-incubation-period/"},"headline":"It Takes About 5 Days for Sick People to Show Coronavirus Symptoms, New Study Says","datePublished":"2020-03-09T21:00:20.000Z","dateModified":"2026-02-24T08:23:45.683Z","description":"A new study estimates coronavirus COVID-19's incubation period at five days, meaning it takes five days to show coronavirus symptoms.","url":"https://time.com/5797300/coronavirus-incubation-period/","keywords":["COVID-19","Research","embargoed study"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/bltb961761d0f2d2a80/698a0b43e76ad222226375ab/coronavirus-incubation-period.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Jamie Ducharme","jobTitle":"Ducharme is a contributor to TIME.","url":"https://time.com/author/jamie-ducharme/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/bltb961761d0f2d2a80/698a0b43e76ad222226375ab/coronavirus-incubation-period.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Coronavirus in Italy","caption":"Coronavirus in Italy","creditText":"Anadolu Agency via Getty Images—2020 Anadolu Agency","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/covid-19/","name":"COVID-19"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/5797300/coronavirus-incubation-period/","name":"It Takes About 5 Days for Sick People to Show Coronavirus Symptoms, New Study Says"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"Some Patients With Coronavirus Only Show Mild Symptoms. 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