The BC-CfE’s Laboratory Director Dr. Zabrina Brumme alongside Dr. Mark Brockman of Simon Fraser University and Dr. Marc Romney of Providence Health Care and UBC co-led research which found that a single dose of the Pfizer-BioNTech COVID-19 vaccine produces a much weaker antibody response in long-term care (LTC) residents than it does in younger healthy adults.
The finding comes after analyzing blood samples collected in late 2020 and early 2021 from residents of LTC and assisted living homes in Metro Vancouver, as well as staff at Providence Health Care.
The pre-print findings have yet to be peer-reviewed, but nonetheless they do raise questions about the timing of the second dose of vaccine for elderly adults.
“Our results indicate that, after one dose of the Pfizer COVID-19 vaccine, elderly people do not generate as robust of an antibody response compared to adults of younger age” says Dr. Brumme. “The vaccine responses in elderly people were also not as functional as those in younger individuals”. Dr. Romney Medical Leader for Medical Microbiology and Virology at St. Paul’s Hospital, Providence Health Care and associate Professor at UBC, added “It will be important to assess whether this observation extends to older persons living in the community as this may inform the optimal timing of the second dose for this population.”
Dr. Brumme’s team drew blood samples from 12 LTC residents and 18 healthcare workers before and after the first vaccine dose. The pre-vaccine timepoint provided a baseline against which the team could measure changes after participants received their first vaccine dose.
The team found that not only did the LTC residents produce lower levels of antibodies than staff members after the first dose, but also the antibodies LTC residents did produce were less adept at blocking the SARS-CoV-2 virus from binding to its target cells.
“The study is one of the first to assess immune response to COVID-19 vaccines in this vulnerable population in Canada,” says Dr. Tim Evans, executive director of the COVID-19 Immunity Task Force, which funded the study.
“The findings correspond with results from other countries that suggest the immune response to mRNA COVID-19 vaccines, as measured by these parameters, is less robust among older people, compared to younger persons. Fortunately, post-first dose infections leading to serious disease are exceedingly rare: real-world clinical evidence from Canada and the U.K. shows that older persons, in LTC or in the community, are well-protected for many weeks by a single dose of an mRNA vaccine. Nevertheless, these findings are a reminder that there may be limits to how long we can stretch the time between doses for seniors and other segments of the population. Close post-vaccine surveillance, as is being done in many jurisdictions in Canada, is essential, and research correlating laboratory tests with clinical outcomes is needed.”At the present time, says Dr. Brockman, the study team “is assessing the strength and function of COVID-19 vaccine responses following two doses of vaccine in their study population” and hopes to have data soon.
The BC-CfE has also recently initiated a study to look at the magnitude and duration of COVID-19 vaccine immune responses in individuals living with HIV, in context of BC’s mass COVID-19 vaccine rollout that is currently in process.