CDC study: Veterans with two mRNA doses saw dip in antibody response after four months

A Centers of Disease Control and Prevention (CDC) study documented a dip in hospitalized veterans’ antibody response four months after receiving two mRNA COVID-19 vaccine doses, supporting the push for boosters.

The research published Thursday concluded both the Pfizer-BioNTech and Moderna vaccines remained effective against hospitalization for veterans four months after the second dose, despite the recorded waning antibody levels. 

Scientists measured “significantly higher” antibody levels among Moderna recipients than Pfizer-BioNTech recipients, although recipients of both saw these levels decline after four months following the second dose.

“These findings from a cohort of older, hospitalized veterans with high prevalences of underlying conditions suggest the importance of booster doses to help maintain long-term protection against severe COVID-19,” the report said. 

Researchers calculated the effectiveness of the Moderna and Pfizer-BioNTech vaccines four months after the second dose at 86 percent and 75 percent, respectively.

The study studied almost 1,900 veterans between Feb. 1 and Sept. 30 across five Veterans Affairs medical centers in Atlanta, New York City, Houston, Los Angeles and Palo Alto, Calif.

Scientists measured the antibody levels among 234 veteran patients who received two doses and had no evidence of previous infection. 

A vast majority of patients were male, with a median age of 67 years old.

The results align with previous studies showing vaccine recipients experiencing waning antibody levels over time. The CDC noted more studies are needed to further understand how antibody levels change over time.