CDC estimates that 35% of coronavirus patients don't have symptoms

In new guidance for mathematical modelers and public heal...

Posted: May 22, 2020 1:59 PM

In new guidance for mathematical modelers and public health officials, the US Centers for Disease Control and Prevention is estimating that about a third of coronavirus infections are asymptomatic.

The CDC also says its "best estimate" is that 0.4% of people who show symptoms and have Covid-19 will die, and the agency estimates that 40% of coronavirus transmission is occurring before people feel sick.

The agency cautions that those numbers are subject to change as more is learned about Covid-19, and it warns that the information is intended for planning purposes. Still, the agency says its estimates are based on real data collected by the agency before April 29.

The numbers are part of five planning scenarios that "are being used by mathematical modelers throughout the federal government," according to the CDC. Four of those scenarios represent "the lower and upper bounds of disease severity and viral transmissibility."

The fifth scenario is the CDC's "current best estimate about viral transmission and disease severity in the United States." In that scenario, the agency described its estimate that 0.4% of people who feel sick with Covid-19 will die.

For people age 65 and older, the CDC puts that number at 1.3%. For people 49 and under, the agency estimated that 0.05% of symptomatic people will die.

Expert pushes back

Under the most severe of the five scenarios outlined -- not the agency's "best estimate" -- the CDC lists a symptomatic case fatality ratio of 0.01, meaning that 1% of people overall with Covid-19 and symptoms would die.

In the least severe scenario, the CDC puts that number at 0.2%.

One expert quickly pushed back on the CDC's estimates.

"While most of these numbers are reasonable, the mortality rates shade far too low," biologist Carl Bergstrom of the University of Washington told CNN.

Bergstrom, an expert in modeling and computer simulations, said the numbers seemed inconsistent with real-world findings.

"Estimates of the numbers infected in places like NYC are way out of line with these estimates. Let us remember that the number of deaths in NYC right now are far more than we would expect if every adult and child in the city had been infected with a flu-like virus. This is not the flu. It is COVID," Bergstrom said.

"As I see it, the 'best estimate' is extremely optimistic, and the 'worst case' scenario is fairly optimistic even as a best estimate. One certainly wants to consider worse scenarios," Bergstrom said of CDC's numbers.

"By introducing these as the official parameter sets for modeling efforts, CDC is influencing the models produced by federal agencies, but also the broader scientific discourse because there will be some pressure to use the CDC standard parameter sets in modeling papers going forward," he said.

"Given that these parameter sets underestimate fatality by a substantial margin compared to current scientific consensus, this is deeply problematic."

Numbers are for planning purposes, CDC says

"The scenarios are intended to advance public health preparedness and planning. They are not predictions or estimates of the expected impact of COVID-19," the CDC says.

It says the numbers do not "reflect the impact of any behavioral changes, social distancing, or other interventions," which would be relevant for some of the agency's estimates -- such as how many infections stem from each case.

Still, the CDC is characterizing the numbers as preliminary estimates from federal agencies, including the CDC and the HHS Office of the Assistant Secretary for Preparedness and Response, that are "designed to help inform decisions by modelers and public health officials who utilize mathematical modeling."

Under the best estimate scenario, the guidance says 3.4% of symptomatic people with Covid-19 will require hospitalization, with that number rising to 7.4% in people 65 and older. The CDC also says it assumes that people without symptoms are just as infectious as those with symptoms.

Huntsville/Redstone
Cloudy
37° wxIcon
Hi: 41° Lo: 35°
Feels Like: 29°
Muscle Shoals
Cloudy
39° wxIcon
Hi: 46° Lo: 35°
Feels Like: 30°
Huntsville/Madison
Cloudy
38° wxIcon
Hi: 41° Lo: 35°
Feels Like: 28°
Decatur
Cloudy
37° wxIcon
Hi: 42° Lo: 37°
Feels Like: 29°
Fort Payne
Cloudy
37° wxIcon
Hi: 42° Lo: 35°
Feels Like: 28°
WAAY Radar
WAAY WAAY-TV Cam
WAAY Temperatures

Alabama Coronavirus Cases

Cases: 417528

Reported Deaths: 6030
CountyCasesDeaths
Jefferson61313888
Mobile29768542
Madison26637185
Tuscaloosa20580268
Montgomery18696304
Shelby18310113
Baldwin16002179
Lee12261101
Morgan12093112
Etowah11604157
Calhoun10982200
Marshall10108107
Houston8474129
Cullman7960104
Limestone790174
Elmore7723101
DeKalb764697
St. Clair7460120
Lauderdale745183
Talladega6102108
Walker5852174
Jackson574441
Blount526483
Colbert525670
Autauga510355
Coffee434256
Dale391081
Franklin363445
Chilton333565
Covington326167
Russell323810
Escambia312442
Dallas300296
Clarke278233
Chambers277869
Tallapoosa2599107
Pike245829
Marion240549
Lawrence240447
Winston223835
Bibb213047
Geneva197431
Marengo197329
Pickens195231
Hale173742
Barbour171236
Butler167958
Fayette166026
Cherokee159630
Henry151119
Monroe144417
Randolph138535
Washington136526
Clay125246
Crenshaw118044
Lamar116619
Cleburne116023
Macon113335
Lowndes108735
Wilcox101221
Bullock98128
Perry95419
Conecuh92920
Sumter88726
Greene75323
Coosa60414
Choctaw51224
Out of AL00
Unassigned00

Tennessee Coronavirus Cases

Cases: 676039

Reported Deaths: 8311
CountyCasesDeaths
Shelby752601102
Davidson69679654
Knox38097389
Hamilton34075324
Rutherford32696282
Unassigned22259128
Williamson21054138
Sumner17980229
Out of TN1581878
Wilson14242154
Montgomery14085148
Sullivan12405209
Washington11757191
Blount11708122
Maury10812122
Bradley1058390
Sevier10320108
Putnam9790136
Madison9011178
Robertson751685
Hamblen6855106
Anderson6678101
Greene6500108
Tipton611664
Gibson5571111
Coffee552981
Dickson529277
Cumberland528672
Bedford523885
Roane510777
Carter5053112
Lawrence502869
McMinn500473
Warren492753
Loudon487750
Dyer469281
Jefferson464975
Monroe447362
Hawkins438668
Franklin403556
Obion396474
Fayette388951
Rhea376155
Lincoln372944
Cocke338956
Weakley337848
Marshall335836
Cheatham330528
Henderson330155
Campbell318139
Giles317371
Hardeman306452
White305543
Carroll304459
Hardin295446
Lauderdale291031
Macon284150
Wayne259519
Henry257357
Overton249142
DeKalb239340
Haywood237245
McNairy233642
Smith228427
Trousdale228314
Marion222731
Scott222431
Hickman219734
Fentress211031
Grainger204935
Claiborne202021
Johnson200531
Morgan186615
Crockett179638
Bledsoe172610
Chester171037
Unicoi164643
Cannon155419
Lake154019
Decatur145926
Polk139817
Grundy138220
Union136821
Sequatchie133318
Humphreys131117
Benton130935
Lewis126820
Meigs111916
Stewart103820
Jackson102821
Perry93725
Houston93122
Clay92026
Moore7888
Pickett66819
Van Buren6487
Hancock3986

Community Events