New study underscores need for COVID-19 booster shots for older adults

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.

During clinical trials of the mRNA COVID-19 vaccines prior to approval by the U.S. Food and Drug Administration, antibody response was shown to be high in older adults, conferring robust protection against infection and hospitalization. However, continued monitoring of these individuals showed a decline in antibodies after six months.

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.

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