The study was published in the Journal of the American Medical Association. Antibodies are proteins in the blood that the immune system makes to protect against infection. They are known to be key players in protecting against SARS-CoV-2 infection.
“Our older populations are potentially more susceptible to the variants even if they are vaccinated,” said lead author Fikadu Tafesse, Ph.D., assistant professor of molecular microbiology and immunology at the OHSU School of Medicine.
Tafesse and his colleagues emphasized that, although they measured decreased antibody response in older people, the vaccine still appeared to be effective enough in preventing serious infections and illness in most people of all ages.
“The good news is that our vaccines are really strong,” Tafesse said.
However, with acceptance of the vaccine declining in Oregon and across the United States, the researchers say their findings underscore the importance of promoting vaccination in local communities.
Vaccines reduce the spread of the virus and new and potentially more transmissible variants, especially for older people who appear to be more susceptible to breakthrough infections.
“The more people are vaccinated, the less the virus circulates,” Tafesse said. “Older people are not entirely safe just because they are vaccinated; the people around them also need to be vaccinated. At the end of the day, this study really means that everyone should get vaccinated to protect the community.”
The researchers measured the immune response in the blood of 50 people two weeks after their second dose of the Pfizer vaccine against COVID-19. They grouped the participants into age groups and then exposed their blood serum in test tubes to the original “wild-type” SARS-CoV-2 virus and to P.1 variant (also known as gamma) that originated in Brazil.
The youngest group, all in their 20s, had a nearly seven-fold increase in antibody response compared to the oldest group of people between 70 and 82 years old. In fact, the lab results reflected a clear linear progression from youngest to oldest: the younger a participant, the more robust the antibody response.
“Older people may be more susceptible to the variants than younger people,” Tafesse said.
The findings highlight the importance of vaccinating older people, as well as others who may be more vulnerable to Covid-19, said co-author Marcel Curlin, MD, associate professor of medicine (infectious diseases) at the OHSU School of Medicine.
“The vaccine still produces strong immune responses compared to natural infection in most older people, even if they are lower than their younger counterparts,” Curlin said. “Vaccination in this group it can make the difference between a serious and a mild illness, and probably reduces the chances of transmitting SARS-CoV-2 to another person.