CDC Ebola Projections Discussion

[Ray]

Since the CDC projections of 500K to 1.4M by Jan 2015 for Sierra Leone and Liberia were released, there have been a number of scientists/public health officials expressing concern about the 2.5X multiplier of WHO reported figures CDC used to reach their 500K-1.4M projection. http://www.cdc.gov/mmwr/preview/mmwrhtml/su6303a1.htm?s_cid=su6303a1_w

Yesterday @FLAHAULT (Antoine Flahault) posted this on Twitter:
"Aren't most previsions made today on #Ebola based on highly unreliable figures and made by Agencies with potential conflicts of interest?"
He goes on to argue that some of the Ebola deaths could be from malaria and that using figures that are dramatically overstated can lead to a crisis in trust in public health officials.

There is this blog post:

http://fivethirtyeight.com/datalab/...w-if-the-cdcs-big-ebola-forecast-is-accurate/

"Neuman said that even without outside intervention, affected societies eventually would reorder themselves to better fight Ebola. He also doubts that people not yet affected are just as likely as those who have been to get infected."

There is a vocal group of experts who think the CDC projections/model is completely inaccurate, modelers should only use official WHO (underestimates) and was used to "scare" up a better international response to the outbreak. Some argue that CDC report should have taken efforts to contain the outbreak into account (medications/hospitals being built/vaccines in development) in their model. Assuming that these interventions will be effective/available.

And then there is this report from Sierra Leone over the weekend:
Former Health Minister Miatta Kargbo and former World Health Organisation Representative Dr. Jacob Mufunda, had ordered that ONLY DEATHS INSIDE CLINICAL FACILITIES were to be recognised as "confirmed deaths" to be announced.

http://news.sl/drwebsite/publish/article_200526287.shtml

 

[JimO]

Re: CDC Ebola Projections Discussion

Back in July I did some rudimentary calculations on projected deaths, assuming the first death in mid-December, and reproductive number (R0) of 1.8. I applied the R0 and projected through next June. The acutal WHO reported fatalities match up pretty well with, but are higher than, the predicted fatalities after about March. The most recent available information put the reported fatalities at ~2,500 on 9/12/14 and the predicted deaths as of 9/12/14 total ~2,100. The predicted deaths going forward are as follows:

12/31/14 - ~40,000

3/20/15 - ~400,000

6/10/15 - ~4,000,000

This, of course, assumes no change in R0 and no change in the period to which R0 applies.

It doesn't take a complex mathematical model to see how dramatically the numbers can rise. And note that the numbers above are deaths, not just cases. This analysis doesn't factor in the CFR directly, but it assumes that the CFR remains constant at levels seen so far in this outbreak.

Also, these numbers could be seen just in Guinea, Liberia, and Sierra Leone, given their combined population of ~20M.

 

[MHSC]

Re: CDC Ebola Projections Discussion

I would not discount the CDC's projections. Of course they are not perfect that's why they are call projections or estimates. These projections are motivating the world to action, by showing them one example of what could happen.

If ebola is not responded to and it breaks out of africa into the dozens of other countries that have poorly developed health care systems, then what? One such country it could eventually reach is Mexico. Approximately 15,000,000 (15 million) people crossed that border between January and April of this year, see the link. That doesn't include the ones that sneak across. http://transborder.bts.gov/programs/international/transborder/TBDR_BC/TBDR_BCQ.html

These people don't have money so they won't go to doctor for a headache and flu like symptoms, they live in crowded groups. They beg on the street, they use our subways, they shop in our stores, they steal a ssn so they can work.
http://www.nytimes.com/2006/09/04/world/americas/04iht-id.2688618.html?pagewanted=all&_r=0

If the wealthy in any of these poorly developed countries become ill, they are going to travel to get better health care. Well developed countries can handle many, many small outbreaks. But if dozens of countries are infected we could potentially have thousands of infected people traveling, eventually creating many tens of thousands of cases before they seek medical care. We have to stop it now or we may have a REAL worst case scenario on our hands and these projections whether extremely accurate or not are a wake up call for those in charge.

 

[MHSC]

Re: CDC Ebola Projections Discussion

By the way, I think they are pretty accurate.

 

[erruve]

Re: CDC Ebola Projections Discussion

I am more worried about India than Mexico. I believe the conditions there would be far worse regarding transmission, and there is a higher likelihood of travel to India than to Mexico.

 

[MHSC]

Re: CDC Ebola Projections Discussion

I am more worried about India than Mexico. I believe the conditions there would be far worse regarding transmission, and there is a higher likelihood of travel to India than to Mexico.

I agree, there is no doubt that India would become infected before Mexico. But if we don't stop ebola and it continues to spread as it is now, Mexico would eventually be infected and that is a threat to the US. I was speaking in terms of a REAL worst case scenario, not the CDC's regional worst case scenario.