Before we get to our friends at the CDC, a refresher because I know people are fighting like hell against child abuse by school boards. This BMJ piece provides the case against school closures. It is relevant because the state of Minnesota and many other states are setting us up again for constant quarantines and closures of schools. (BMJ Article)
Every now and then we get a batch of new studies published by the CDC. I am always a little suspicious now, because they have been so obviously politicized, about the timing. This batch appears to be aimed at reassuring us about vaccines, but some of the data is a little concerning.
The first study looks at the effectiveness of vaccines among nursing home residents, before and after the Delta invasion. We all know the frail elderly, particularly in nursing homes, have been the special target for CV-19. So while vaccines are generally less effective among the elderly, any help in this group would be critical. Earlier in the epidemic, pre-Delta, effectiveness at preventing infection, which most people now recognize isn’t that relevant, was around 74%. In the Delta era, effectiveness has declined to around 53%. Severity was not specifically discussed, but other studies have suggested ongoing protection against hospitalizations and deaths even among this group. Lag time from vaccination to infection was also not discussed. (CDC Study)
Next up, a study on the overall effectiveness of vaccines among the adult population. (CDC Study) These researchers assessed effect on hospitalization. Among all adults, effectiveness was 86% but if immuno-compromised persons were removed from the analysis, effectiveness rose to 90%. The study only covered 6 months post vaccination, but saw no waning of effectiveness during that time.
Finally a study from New York on effectiveness among adults. (CDC Study) From the beginning of May to near the end of July, overall effectiveness against preventing infection declined from 92% to 80%. Protection against hospitalization remained high throughout the study period, at over 92%. Case rates by age group were similar between vaxed and unvaxed group. And across age groups, vaccine effectiveness in regard to cases was similar, which is somewhat surprising, but there wasn’t generally a long time of observation after vaccination. I would expect less effectiveness in the long run among older persons. Effectiveness against hospitalization did show some age effect, with somewhat less effectiveness among the elderly.
I think the overall message from the CDC is vaccines work, but their effectiveness may wane over time, so get those boosters. And they work well to protect against severe disease, maybe not so much against infections, at least infections measured by PCR tests. Meanwhile, it appears the immunity from infection is more durable, although they are likely hiding reinfection data because it would make that clear. A failure to design the best vaccines in part may be responsible for the appearance of waning protection.