In a new study from CDC, researchers found COVID-19 vaccine protection is increased after three doses but wanes with time since vaccination after receipt of two or three doses.
They examined vaccine effectiveness among U.S. adults at various points after receipt of a second or third vaccine dose during periods of delta and omicron variant predominance.
A total of 241,204 emergency encounters and 93,408 hospitalizations were examined across 10 states from Aug. 26, 2021, to Jan. 22, 2022.
The researchers found that after receipt of both two and three doses, vaccine protection was lower during the omicron-predominant versus the delta-predominant period at all time points.
VE was higher after receipt of a third dose versus a second dose during both periods; however, with increasing time since vaccination, vaccine protection waned.
Vaccine protection against emergency visits was 87 percent during the first two months after the third dose during the omicron period and decreased to 66 percent among those vaccinated four to five months earlier; the corresponding vaccine protection against hospitalization was 91 and 78 percent, respectively.
vaccine protection was generally higher for protection against hospitalization than emergency visits in both periods.
The team says the finding that protection conferred by mRNA vaccines waned in the months after receipt of a third vaccine dose reinforces the importance of further consideration of additional doses.
If you care about Covid, please read studies about your maximum risks of COVID infection with and without masks, and some Americans with COVID-19 get deadly ‘black fungus’ disease.
For more information about health, please see recent studies that two-drug combo could fight COVID-19 effectively, and results showing this drug could help treat lung damage in COVID-19.
The study is published in Morbidity and Mortality Weekly Report and was conducted by Jill M. Ferdinands et al.
Copyright © 2022 Knowridge Science Report. All rights reserved.
