The findings, published in Cell Reports Medicine, are from a clinical trial sponsored by the U.S. National Institute of Allergy and Infectious Diseases.
As part of a "mix and match" clinical trial, researchers administered COVID-19 booster vaccines to adults in the United States who had previously received a primary COVID-19 vaccination series.
Researchers then evaluated immune responses over time. They found that nearly all vaccine combinations evaluated elicited high levels of neutralizing antibodies to the Omicron BA.1 sub-lineage.
However, immune responses to Omicron in all groups waned substantially, with neutralizing antibody levels decreasing 2.4- to 5.3-fold by three months after booster shots, according to the study.
The researchers noted that the findings are consistent with real-world reports showing waning protection against SARS-CoV-2 infection during the Omicron wave in people who received a primary vaccine series plus a booster shot.
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