NEW YORK – A recently published scientific study has concluded a 21-day quarantine period for Ebola is not enough.
Challenging the scientific basis for the World Health Organization and the Centers for Disease Control and Prevention recommendation, the study concludes 31 days may be required to have a 95 percent certainty a person has not contacted Ebola.
Dr. Charles Haas of the Department of Civil, Architectural and Environmental Engineering at Drexel University is the author the study, “On the Quarantine Period for the Ebola Virus,” published Oct. 13 in the scientific journal PLOS: Currents Outbreaks. He has concluded a 21-day quarantine period for Ebola may result in the release of individuals who still have up to a 12 percent risk of having the disease.
“While the 21-day quarantine value currently used may have arose from reasonable interpretation of early outbreak data, this work suggests a reconsideration is in order and that 21 days may not be sufficiently protective to public health,” Haas concluded, suggesting the WHO recommendation was based on faulty data analysis.
Examining more recent disease data from the current West African outbreak as well as from other outbreaks, Haas suggests a 31-day quarantine period may be necessary.
Haas criticizes the WHO for relying on potentially flawed data, noting “the precise origin of this assessment is unclear.” It appears the U.N. agency relied primarily on studies of the 1976 Zaire outbreak or the 2000 Uganda outbreak, “both of which reported (without detailed analysis) a maximum observed incubation of 21 days.”
As for the origin of the WHO’s current 21-day quarantine recommendation, Haas cited a study the WHO published in September. It was based only on an analysis of data from the first nine months of the current Ebola outbreak in West Africa. It reported an average incubation period of 11.4 days with an upper 95th percentile of 21 days.
Haas’ analysis, however, was based on more recent data from the current West Africa outbreak, as well as a larger dataset of cases from the 1995 outbreak in the Congo that proved a quarantine of 21 days was too short. The 1995 data found 12 percent of the Ebola-exposed patients released developed the disease and become contagious sometime after 21 days.
Haas stressed that analysis of the more extensive patient database set from the 1995 Congo outbreak suggests a quarantine time of 31 days is required to reach the upper 95th percentile of the Ebola incubation time distribution.
A summary of the research published on the Drexel University website said, “Haas, who has extensive background in analyzing risk of transmitting biological pathogens, explains that these quarantine periods must be determined by looking at the cost of enforcing the quarantine versus the cost of releasing exposed individuals.”
The note concludes, “Obviously, with more contagious and potentially deadly diseases the cost of making a mistake on the short side when determining a quarantine is extremely high.”
Haas said it’s clear that pathogens with a high degree of transmissibility and/or a high degree of severity, should have a longer quarantine time.
“The purpose of this paper is not to estimate where the balancing point should be, but to suggest a method for determining the balancing point,” he said.
As WND reported, the Obama administration has stated U.S. health-care workers returning home after treating Ebola-infected patients in West Africa should be treated as “heroes” rather than be punished by being placed in quarantine after traveling by air from West Africa to the United States.
On Monday, the CDC redefined previously published health-care protocols recommending state health officials should not mandate a 21-day quarantine for U.S. citizens, including health-care workers, upon their return to the United States after exposure to Ebola in West Africa.
Instead, U.S. citizens, including health-care workers, exposed to Ebola in West Africa should be placed under “active monitoring,” requiring them to make daily telephone calls to state health officials reporting possible any symptoms of Ebola that may develop, including fever, in the first 21 days after returning home.
WND has also reported the Pentagon decision to place 11 U.S. soldiers returning from Liberia in 21-days quarantine at a U.S. military base in Vicenza, Italy, represents an apparent policy conflict with the “active monitoring” policy.