Thread by @enn_nafnlaus

Good review from the CDC published yesterday of protection levels from past infection vs. vaccination - worth a bookmark.

cdc.gov/coronavirus/20…

Of particular note, the section "Immune Response Kinetics and Duration of Protection" is worth a read.

One criticism about the CDC's stance that jumps immediately to mind is: they show that in most contexts, protection from infection vs. 2-shot vaccination is roughly similar. They then go on to show that it's well evidenced that vaccination following infection significantly...

... further increases protection - justifying their policy they've held since the beginning of offering full course of vaccination for previously infected individuals.

Well, then why did you wait so long to offer the same benefit to people who got their roughly similar level...

... of immunity from vaccination? Why did they have to wait? Why were people who had been previously infected offered two additional shots, but people who got their roughly similar level of immunity from vaccination maybe offered one additional? Why the infection favouritism?

They do note one recent study showing 5,5x higher odds of reinfection than post-vaccine breakthrough (cdc.gov/mmwr/volumes/7…). But this study is only two days old; it cannot justify a policy that's been in place all year; previous studies cited show similar protection.

The consequence of this sort of uneven policy is dramatic. For example, in one study, the mean measured antibody level after only 2x Pfizer was ~2k U/ml, but after infection + 2x Pfizer it was ~19k U/ml for asymptomatic and ~30k U/ml for symptomatic.

pubmed.ncbi.nlm.nih.gov/33788281/

So in short, this CDC paper reinforces to me the strangeness of their policy, where even the rules for getting 1x booster are restrictive. But regardless, the page is an excellent review of the literature from an authoritative source, and I really recommend reading it.

* Reinfection / breakthrough *hospitalizations*, not *cases*.