The new coronavirus vaccine data released yesterday by the CDC confirms what other recent research has been saying: The coronavirus vaccines' effectiveness against infection has decreased over time.
Between the lines: There's little to no data that the vaccines' effectiveness against hospitalization will eventually follow suit.
Get market news worthy of your time with Axios Markets. Subscribe for free.
Driving the news: The CDC released three new studies focusing on the vaccines' effectiveness, particularly in light of the Delta variant.
One looked at Pfizer and Moderna's effectiveness against infections among nursing home residents over time, and found that it dropped from 75% pre-Delta to 53% when Delta became dominant. It didn't differentiate between asymptomatic, symptomatic and severe infections.
Another used data from 21 hospitals to estimate the mRNA vaccines' effectiveness against hospitalization over time, and found there was no significant change in effectiveness from mid-March to mid-July.
The third, using New York state data, found that all three vaccines' effectiveness against infection dropped from 92% in early May to 80% at the end of July, but the effectiveness against hospitalization remained relatively stable.
Reality check: This is all good news for most vaccinated people — your vaccines will keep you alive and out of the hospital.
It's not so great for some vulnerable populations, particularly nursing home residents, who may be less protected than they'd thought.
"Additional evaluations are needed to understand whether protection against severe disease in nursing home residents is also declining over time," the nursing home study warns.
Residents' risk level is compounded by the high rate of unvaccinated nursing home employees.
Be smart: The Biden administration's worst nightmare is finding out about declining effectiveness by a spike in real-world death rates in a few months. They've instead decided to get ahead of the virus by boosting most people's level of protection, starting with the most vulnerable.
What we're watching: Recent Israeli data suggests that vaccine effectiveness against severe disease has fallen over time among adults 65 and older who haven't received a booster shot.
We need way more data to know if the trend is real. It's still entirely possible the vaccines remain effective against severe disease well into the future — at least for the younger population — meaning the U.S. jumped the gun on extra shots.
But if it is an accurate foreshadowing of how the vaccines will work in the U.S., the Biden administration's decision will likely save American lives — which is the ultimate point of the booster decision.
Like this article? Get more from Axios and subscribe to Axios Markets for free.