A team of scientists from U.S. Centers for Disease Control and Prevention (CDC) has carefully analyzed patterns of novel coronavirus (COVID-19) infection and incubation period, and confirmed that the 14-day quarantine period is suitable in people exposed to the virus to minimize its spread.
New evidence by researchers from @JohnsHopkinsSPH suggests that persons infected with COVID-19 may be #symptom-free for about 5 days on average, and should expect to experience symptoms within 12 days.
— Annals of Int Med (@AnnalsofIM) March 9, 2020
The virus, which now has an official name of severe acute respiratory coronavirus 2 (SARS-CoV-2), has so far reached 115 countries and infected over 114,000 people. It is currently the biggest medical mystery for the scientists because of its remarkable tenacity, transmission rate (Ro) and case fatality rate (CFR).
The virus is spreading so fast scientists are struggling to stay apace with it let alone devise anti-retroviral treatment or vaccination. For the same reason, even epidemiological data, containing authentic information on the incubation and isolation period in the infected and suspected population, is limited.
Dr. Lauer and Team’s Effort to Estimate Incubation Period of Coronavirus
To investigate and confirm the length of SARS-CoV-2 incubation period and describe its public health implications, Dr. Stephen Lauer, a Ph.D. scholar at John Hopkins University, and scientists conducted a pool analysis of the cluster of severe pneumonia cases occurring between January and February this year. All 181 cases belonged to Wuhan, China, the epicenter of coronavirus breakout.
Wuhan is the largest city of central China with a burgeoning population of over 11 million. The city, along with Huanggang and Ezhou, has been ‘quarantined’ and cut off from rest of the country since January 23, 2020. The World Health Organization (WHO) has dubbed the viral infection ‘unprecedented in public health history’ and has appreciated China’s efforts to minimize the spread to other provinces and countries.
The WHO has declared SARS-CoV-2 a Public Health Emergency of International Concern (PHEIC) since January 30th, 2020. Ever since, all citizens returning from Hubei province, China, are being quarantined for a period of 14 days on the instructions of CDC.
Coronavirus is little understood, its origin and evolution is so far unknown. Worldwide efforts are underway to determine and arrest its spread. Dr. Lauer and team’s effort are commendable in that they are moving a step closer to understanding the deadly virus that is spreading uncontrollably and has thus far swallowed over 4,000 lives globally.
The researchers obtained data on patient demographics which included the time of first exposure, nature of symptoms and hospital admission dates. The purpose was to determine and estimate the incubation period of the virus.
They based their estimates on news, reports and press releases obtained from 50 provinces in China and found that coronavirus infection had an average incubation period of 5.1 days. As per estimates, a person exposed to the virus would develop the symptoms within 12 days. The researchers also found that out of 10,000 infected cases, approximately 100 people will develop the infection after 14 days and therefore need to be isolated and monitored consistently. The incubation period for coronavirus is exactly similar to other strains of coronavirus (that cause SARS and Middle-East Respiratory Syndrome), i.e., 5 days. Therefore, it makes sense that the quarantine period should be similar, i.e., 14 days. During this period, the patient develops symptoms and is most likely to spread infection.
Dr. Lauer believes the information is valuable since ‘the incubation period can inform several important public health activities for infectious diseases, including active monitoring, surveillance, control, and modeling’.
This will allow effective monitoring of the exposed patients as well as assess the length of quarantine period.
He added, “Active monitoring requires potentially exposed persons to contact local health authorities to report their health status every day. Understanding the length of active monitoring needed to limit the risk for missing SARS-CoV-2 infections is necessary for health departments to effectively use limited resources.”