CDC’s Worst Case Scenario: 1.4 Million Ebola Cases

A new CDC report says there are likely 2.5 times as many Ebola cases as are being reported, and that the disease could reach 1.4 million people by early next year.


A new report from the Centers for Disease Control and Prevention warns the international community that if it doesn’t step up efforts to combat Ebola, it could reach millions by January.

The investigation, a part of the CDC’s Morbidity and Mortality Weekly Report (MMWR), lays out the best- and worst-case scenarios for the Ebola epidemic in West Africa, which has claimed more than 2,500 lives. Using numbers gathered from Sierra Leone and Liberia in August, it presents the first hard data to predict how dependent the scale of the epidemic is on our response.

Gayle Smith, Special Assistant to the President and Senior Director, National Security Council, stressed the importance of taking the numbers seriously in a press briefing Tuesday morning. “Every hour counts. Every minute counts,” said Smith. “There is data that shows if we don’t respond steadily, effectively, and on time, we will be looking at an even more unprecedented situation.”

A better system for calculating the numbers is needed.

The CDC says that the current numbers on record for the epidemic, 5,843 cases and 2,803 deaths, are “substantially underreported.” In order to account for this difference, the CDC created an Ebola Response modeling tool, which they are calling “EbolaResponse,” to predict the discrepancy mathematically. The authors of the study highlight the importance of this new, unprecedented tool. “The data corrected for underreporting reflects the potential range of uncertainty regarding the actual number of cases that might occur,” the report reads.

There are likely 2.5 times as many cases as are being reported.

According to the work of EbolaResponse, the number of reported cases in Liberia and Sierra Leone may be 2.5 times higher than reported. This means that, by current predictions, an estimate of 8,000 cases in these two countries by September 30 may look more like 21,000. The CDC points to the rate at which the cases are increasing as evidence that the numbers are too low. For example, in Liberia, cases are reportedly doubling every 15 to 20 days. In Sierra Leone, they are doubling every 30 to 40.

The epidemic, in a worst-case scenario, could reach millions.

According to current numbers from the World Health Organization (WHO), the reported cases of Ebola in Sierra Leone and Guinea on September 9 were 2,407. By these estimates, the number of cases between the two countries may reach 550,000 by January. However, accounting for the imprecision of current numbers, which WHO Director Dr. Margaret Chan calls a “vast underestimate” of reality, there may be as many as 1.4 million cases by January 20.

Containing the response means ramping up treatment.

In order to contain the epidemic, the CDC estimates that approximately 70 percent of Ebola patients must be receiving care in a medical facility. Once this number is reached, the authors of the report estimate that the outbreak will decrease at a “rate nearly equal to the initial rate of increase.”

Delay could be catastrophic.

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For every 30-day window that response to the epidemic is delayed, the CDC estimates that an approximate tripling in cases may occur. With 125 CDC experts on the ground, the agency says it is “developing innovative methods” to isolate patients who cannot make it in to a treatment center in order to “help disrupt Ebola transmission in communities.”


Despite the high numbers, the CDC has stressed the notion that a quick response may render them “very unlikely.” Thomas Frieden, who led the call, was careful to caution that Americans not take the numbers as indicators of what will happen, but rather predictions of what could. “These are not projections,” Frieden during the Tuesday press conference. “What we have done is outline what might happen.”

Frieden, who weeks ago claimed the “window was closing” on Ebola containment efforts, reaffirmed the need for an urgent response. “A surge now can break the epidemic’s back. It is possible,” he said. “We can be on track to turning it around, but costs of delay are significant and that’s why the response is so incredibly important, because every day counts and will make a difference.”