Drop in COVID Vaccine Effectiveness Suggests Need for Boosters

Dec. 10, 2021 — The effectiveness of the 2 most typical COVID-19 vaccines declined over time in an older group of sufferers, suggesting that booster doses could also be wanted to guard recipients over the long run, in line with a brand new research.

Also seen in that group of U.S. veterans, who had a median age of 67: Those receiving “the Moderna vaccine consistently had higher antibody levels, compared with recipients of the Pfizer-BioNTech vaccine, across age groups and time since vaccination,” mentioned Kristina L. Bajema, MD, of the CDC’s COVID-19 Response Team, and associates.

Effectiveness of the Moderna vaccine was 89.6% at 14-119 days after sufferers had obtained the second dose, in contrast with 86.0% for the Pfizer vaccine. After 120 or extra days, vaccine effectiveness had dropped to 86.1% for Moderna and 75.1% for Pfizer, the investigators reported within the Morbidity and Mortality Weekly Report.

Levels of the related antibodies — anti-spike immunoglobulin (IgG) and anti-receptor binding area (RBD) IgG — confirmed an analogous sample: Lower after the 120-day mark for each vaccines, however increased at each time intervals for Moderna than for Pfizer. These variations in antibody ranges are per different research, researchers mentioned, and could also be the results of the Moderna vaccine’s increased antigen content material and its longer interval between doses.

All 1,896 veterans within the research had been enrolled whereas they had been hospitalized with COVID-like sickness at 5 Veterans Affairs medical facilities across the nation (Atlanta, Houston, Los Angeles, New York City, and Palo Alto, CA). The group included sufferers who examined constructive and people who had been detrimental for COVID-19 when first hospitalized; 799 ultimately had been absolutely vaccinated. About 58% of the group was age 65 or older.

Both vaccines had been simpler in youthful sufferers: 89.4% for these underneath 65 years and 72.9% for these 65 and older within the Pfizer group, in comparison with 94.5% and 78.6%, respectively, for Moderna. The identical drop-off in effectiveness after 120 days was seen for each age teams, the researchers famous.

The age impact could also be trigger for concern.

“Overall, for both vaccine products, antibody levels in this cohort of older U.S. veterans with high prevalences of underlying medical conditions were substantially lower than levels seen among younger, healthy volunteers or health care personnel in other studies,” they mentioned, including that booster doses could also be wanted “to help maintain long-term protection against severe COVID-19.”