“Relative to no #vaccination,TwoDose VE against #hospitalization was estimated at 25% at 150 days or more after receipt. #ThirdDose VE was 68% at 7 to 119 days and 36% thereafter (median days, 235). #FourthDose VE among patients aged 65 years or older was 66% at 7 to 59 days and 57% thereafter (median days, 88).”

https://www.cidrap.umn.edu/covid-19/covid-vaccine-efficacy-against-ba45-hospital-stay-fell-68-36-after-4-months