In a study of more than 80 men and women from Baltimore, Maryland, Johns Hopkins researchers have added to evidence that COVID-19 booster shots are essential for maintaining long-term immunity against infection, particularly among older adults.
Results of the study, published Aug. 15 in Clinical Infectious Diseases, directly support the CDC vaccination guidelines recommending COVID-19 boosters, investigators say.
A previous study documented a significant decline in protective antibody response among all vaccine recipients six months after an initial two-dose series of mRNA vaccines, particularly in older adults whose immune systems weaken with age and respond less efficiently to viral and bacterial infections. These previous studies also showed a sharper decline in immune response in men compared with women in adults over 74 years.
For the new study, investigators at Johns Hopkins Medicine tested COVID-19 antibody levels in blood samples from more than 80 adults ages 75–98 who had two initial doses of the mRNA vaccines made by either Pfizer or Moderna and no known history of COVID infection.
As a comparison group, researchers also tested the blood of 84 adults under 75 years old with the same vaccination and infection history.
However, when blood samples were again taken and tested 14–30 days after a booster shot, antibody levels for older adults matched those in the younger group. A third dose also eliminated disparities between males and females within the same age group.
