In a study of more than 80 men and women in Baltimore, Maryland, Johns Hopkins researchers have added evidence that COVID-19 booster shots are essential for maintaining long-term immunity against the infection, especially among older adults .
According to the researchers, the results of the study, published Aug. 15 in Clinical Infectious Diseases, directly support the CDC’s vaccination guidelines recommending COVID-19 boosters.
A previous study documented a significant decrease in the 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 responds less efficiently to viral and bacterial infections. These previous studies also showed a stronger decline in the immune response in men compared to women in adults older than 74 years.
During clinical trials of COVID-19 mRNA vaccines prior to approval by the US Food and Drug Administration, the antibody response was shown to be high in older adults, which confers solid protection against infection and hospitalization. However, continued follow-up of these individuals showed a decrease in antibodies after six months.
For the new study, Johns Hopkins Medicine researchers tested the levels of COVID-19 antibodies in blood samples from more than 80 adults ages 75 to 98 who had two initial doses of the mRNA vaccines made by Pfizer or Moderna and no known history of COVID infection. .
As a comparison group, the researchers also tested the blood of 84 adults younger than 75 with the same vaccination and infection history.
These initial samples showed that older adults had antibody levels three to eight times lower than the younger group, but older men in particular had antibody levels one to three times lower than their female counterparts.
However, when blood samples were taken again and tested 14 to 30 days after a booster injection, the older adults’ antibody levels matched those of the younger group. A third dose also eliminated disparities between men and women within the same age group.
The data support CDC guidelines for vaccination against COVID-19 and state that the vaccine is initially capable of generating a good antibody response.”
Sean Leng, MD, Ph.D., professor of medicine at Johns Hopkins University School of Medicine
Dr. Sean Leng specializes in geriatric medicine at Johns Hopkins University School of Medicine.
But, he adds, older people should be especially encouraged to get the vaccine and boosters to keep them protected from emerging infections as immunity wanes.
Leng says the study also underscores the importance of continued research into factors that can affect immunity, such as vaccine type, age, sex, and frailty.
Source:
Journal reference:
Shapiro, JR, et al. (2022) Association of frailty, age and biological sex with severe acute respiratory syndrome coronavirus 2 messenger RNA vaccine-induced immunity in the elderly. Clinical Infectious Diseases. doi.org/10.1093/cid/ciac397.