We had warned two months ago that the CDC had erred in dropping the tracking of COVID-19 breakthrough cases and not doing more to track serious breakthrough cases with more detail.  This has led to tremendous confusion and bickering among the White House, the CDC, and the FDA regarding the need and timeline for rolling out vaccine boosters.  Somehow the FDA decided to ignore a lot of good data from the UK, Israel, Iceland, and Singapore regarding the seriousness of breakthroughs.  Now the CDC is leaning toward quicker and broader booster rollout.  Why?

One reason is that yesterday, the CDC reported a big jump in breakout hospitalizations and deaths due primarily to the addition of one more state in their weekly report.  Based on the trend over the last 10 weeks, everyone had expected 3,400 cumulative breakthrough deaths to be reported yesterday (red curve in graph above and table below).  That they got 4,493 was probably a huge shock.  It meant that the total breakthrough deaths over the last 10 weeks were ~3,300, 37% higher than the 2,400 they had expected.  This meant that the USA had 37% more breakthrough deaths due to the Delta and vaccines waning than they had thought just two days earlier.  The graph above shows how the new cumulative breakthrough death curve (blue) might look like had all 50 states and territories reported consistently all along.

How could this happen?  One state probably just acknowledged that they had 1,060 breakthrough deaths that they had not counted/reported before this week and that every week’s breakthrough deaths for the USA over the last 10 weeks had been understated by ~28% and breakthrough hospitalizations by ~15%. On July 12, the CDC breakthrough death count should have been ~1,200 rather than ~1,063, and on 9/20 it had grown to 4,493 due to a very virulent Delta variant. 

That this included a large historical restatement does not make it any less significant for the CDC or the USA – it is equivalent to NY finding out that they had undercounted the number of nursing home deaths due to COVID-19 last spring and had to make a data dump to correct.  It means that the prior CDC narrative that breakthrough deaths are rare is wrong and is far more likely than they had thought.  Rather than admit that they had mismanaged data again (for the nth time), Dr. Walensky decided to broaden booster usage on her own yesterday – mystifying thousands of scientists and reporters.  The truth is the USA needs boosters to stem the current surge almost as much as they need to vaccinate more people. 

Week EndingCum BK HospCum BK Deaths7-day BK Hosp7-day BK Deaths
20-Sep 19,1364,4933,346 1,453
13-Sep15,7903,0401,675    365
6-Sep14,1152,6751,207    238
30-Aug12,9082,4371,858     374
23-Aug11,0502,0631,334     234
16-Aug 9,7161,8291,662 242
9-Aug 8,0541,587   529        80
2-Aug 7,5251,507   938     244
26-Jul 6,5871,263   627      122
19-Jul 5,9601,141   740        78
12-Jul 5,2201,063  
7/19-9/20 totals 13,916  3,430
Source: https://www.cdc.gov/vaccines/covid-19/health-departments/breakthrough-cases.html