Thread by @mahesh_shenai

1a/ 🚩UPDATE: Last week, I posted a critique

https://twitter.com/mahesh_shenai/status/1517551215067992064

of the CDC/MMWR study: cdc.gov/mmwr/volumes/7…. One of my points (4b) highlighted the misleading claim that “9 in 10” hosp. children were unvaxed. I made an inquiry to the MMWR, and got a response. 🧵👇

1b/ Bottom line – they present technically true statistics taken out of context, and produce simplified graphics that are easily amplified in social media, without scrutiny. However, we NEED to scrutinize!

2a/ The claim, centered in their “graphic” summary states that 9 in 10 children who were hospitalized with confirmed C-19 illness, is based on their review of 349 records, of which 301 were unvaccinated (86.2%). So crudely, yes – 9 of 10 children in their data set was unvaxed.

2b/ HOWEVER, in study period of12/19/2021 – 2/28/2022, the vast majority of 5-11yos were unvaxed. Auths claim vax rate was about 32% at END of study, but it was ~13% at start. Assuming linearity, the avg. vax rate in the study period was about 18% (about 8 in 10 were unvaxed).

2c/ Accounting for approximations, statistical variation etc., the 9 in 10 in the MMWR sample is virtually NO DIFFERENT than the 8-9/10 proportion of children who were unvaccinated in the community, during the study time!

2d/ The auths could have provided some comparison to the % unvaccinated in the community. However, they found it more convenient to report the crude “9 in 10” statistic, instead.

3a/ So, I inquired in an email to the author, on the context and validity of the claim - because science requires DIALOGUE:

3b/ And their response confirmed my critique, that “we did not correct for baseline vaccination rates in the catchment areas when examining the proportion of vaccinated vs. unvaccinated children during the early month of Omicron predominance.” (!)

3c/ They further write that this “9 in 10” stat is solely “DESCRIPTIVE” – a simple stat(=301/349), rather than INFERENTIAL which allows generalizations about a hypothesis. That the CDC/MMWR CHOSE to publish this misleading stat as the CENTRAL POINT of the infographic is telling

3d/ The message they want to promote is at the bottom of the infographic: “ Protect all eligible children by keeping their vaccinations up to date.” The misleading “9 in 10” stat was clearly placed to gain support of the unwitting on social media.

4a/ In fact, while we are on the topic, the other two infographic claims are also misleading.

4b/ They claim that “3 in 10” children hosp. with C19 had NO underlying conditions. The STAT is true over all children in the study, but its simply NOT reported in terms of vax status (Table 1). Yet, the graphic implies vax prevents hosp. in kids w/o underlying conditions.

4c/ The same graphic claims “2 in 10” required ICU care. Again, this is true across both unvaxed and vaxed kids. But the supplementary table shows that ICU admission in both unvaxed and vaxed were statistically similar.

4d/ SO, ALL 3 CLAIMS ON THEIR GRAPHIC MISLEAD into believing this study strongly supports need to vax 5-11 yos to prevent hosp. Instead, it shows relative risk reduction is modest, absolute risk reduction is minimal, and there is no identifiable difference in outcomes w/ vax.

5a/ The @cdc @CDCDirector needs to be held to a higher standard than media outlets. Data should be presented in an accurate and honest manner, regardless of how it reflects on the desired narrative. I truly hope they can change their ways, it is important for public health!

@cdc @CDCDirector 5b/ And at least, I do appreciate that the MMWR got back to my inquiry – dialogue is the first step in a healthy debate. That is a positive.

@cdc @CDCDirector 6/ Thank you!