21-Day Quarantine Period May be Too Short to Prevent the Spread of Ebola Virus

Could 21 days of quarantine be too short to prevent the spread of Ebola Virus? That might be the case, according to new research. Scientists have suggested that 21 days, which has been the quarantine period for individuals exposed to the virus, may not completely prevent its spread.

The new study examines the murky basis for our knowledge about the virus. More specifically, it looks at previous outbreaks in Africa in 1976 in Zaire and 2000 in Uganda, as well as the first nine months of the current outbreak. In both of the past cases, data gathered by the World Health Organization reported a 2 to 21-day incubation period for the virus. This means that after 21 days if an individual does not develop symptoms, he is likely not infected or contagious.

"Twenty-one days has been regarded as the appropriate quarantine period for holding individuals potentially exposed to Ebola Virus to reduce risk of contagion, but there does not appear to be a systemic discussion of the basis for this period," said Charles Haas, the lead researcher, in a news release. "While the 21-day quarantine value, currently used, may have arisen from reasonable interpretation of early outbreak data, the work suggests reconsiderations is in order and that 21 days might not be sufficiently protective of public health."

In fact, the researchers found, after looking more broadly at data from other Ebola outbreaks, the range of deviation is between .1 and 12 percent. This means there could be up to a 12 percent chance that someone could be infected after the 21-day quarantine.

"Clearly for pathogens that have a high degree of transmissibility and/or a high degree of severity, the quarantine time should be greater than for agents with lower transmissibility and/or severity," said Haas. "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."

The findings are published in the journal PLOS Current Outbreaks.