October 07, 2022
Release Subtitle:
Researchers from Japan report that the elderly population show a low immune response to the third mRNA COVID-19 booster vaccine
Release Summary Text:
Vaccines against COVID-19 induce the immune system to produce
neutralizing antibodies, and boosters ensure their continued production.
Researchers from Japan now report that their elderly population
produced a very low antibody titer when compared with the younger
cohorts. They used a unique fingertip blood collection method to analyze
whole blood for circulating antibodies against SARS-CoV-2. The
researchers also propose a triage system to address the elderly patients
with poor or low post-booster immune response.
Full text of release:
The coronavirus 2019 disease (COVID-19) pandemic has affected millions
worldwide and claimed multiple lives. The elderly—aged above 60
years—remain the most vulnerable group. They have been more susceptible
in contracting the virus and many have succumbed to the infection.
Long-term care facilities (LTCF) and day-care centers for the elderly
have become potential sources of virus transmission; unfortunately, a
large proportion of the global elderly population is dependent on these
establishments.
The recently developed vaccines and boosters have emerged as a shield
against COVID-19. They activate the body’s immune system and induce the
production of antibodies to neutralize the virus. Carefully planned
booster doses of the vaccine act as reinforcements to help keep up the
body’s defense against the virus. The extent of this defense, i.e.,
vaccine-induced immune activation, can be estimated by measuring the
titer or concentration of antibodies circulating in the vaccinated
person’s body.
It has been suggested that vulnerable groups may have reduced defense
despite being vaccinated and receiving boosters. To understand the risk
in the vaccinated elderly population, a group of researchers led by
Prof. Masanori Nakayama, from the Organization for Research Strategy and
Development, Okayama University, and Dr. Hideharu Hagiya, from Okayama
University Graduate School of Medicine, set out to assess the body’s
immune response in elderly Japanese who had received their third vaccine
dose. Explaining the motivation behind their study, Prof. Nakayama
says, “Despite vaccinations, several
elderly patients in Japan are becoming ill during cluster outbreaks,
some being critical. Therefore, we felt the need to investigate the
antibody titers post-mRNA COVID-19 booster vaccine in the elderly.”
The team analyzed antibody titers against the COVID-19-causative virus,
SARS-CoV-2, after the third booster vaccine had been administered. The
study included 1,046 elderly people from 23 different care facilities.
Each participant had received two doses of either Moderna or Pfizer mRNA
vaccine at least six months prior to the start of the study. A
comparison between the antibody titers between the elderly and the young
was also drawn for better clarity.
Most often, blood is drawn from the veins for titer analysis, which
could be difficult and discomforting for the elderly. To address this
problem, the researchers developed a unique solution; they estimated the
antibody titers from blood drawn simply from the fingertips. They used
the “Mokobio SARS-CoV-2 IgM & IgG Quantum Dot immunoassay” for the
point-of-care fingertip whole blood assay and found that the antibody
titers were widely distributed in each age group assessed.
The results revealed that the number and proportion of non-responders,
i.e., those with antibody titers below 1000 U/mL at any test time after
vaccination, increased with age. Nearly 10% of the participants had
negligible antibody production despite receiving additional vaccine
dose. Also, among the COVID-19 survivors in the assessed clusters, the
antibody titers measured after a month were significantly higher when
compared with those receiving the third booster dose.
Further analysis showed that the proportion of responders (those with
antibody titers above 1000 U/mL) decreased as the age of individuals
increased from 70 to 90 years. The researchers speculated the reason for
this trend to be the immunological aging of a naturally aging human
body. Apparently, people lose their ability to respond to foreign bodies
as they age, becoming slow or non-responsive to vaccines. This explains
why the elderly are more susceptible to infectious diseases.
These fascinating findings have been made available online on July 11, 2022 and published as a letter to the editor in the Journal of Infection.
As life strives to regain normalcy alongside COVID-19, newer strategies
continue to be drawn aiming to keep the world safe from the virus. This
study proposes such a strategy keeping the long-term safety of the
elderly in mind. Elderly people in the LTCF show a lower response to
mRNA booster vaccines and may be apparent non-responders. Thus, it is
critical to develop elderly-oriented serological testing protocols after
vaccination for better disease management.
Talking about the future implications of their study, Prof. Nakayama explains, “For
social normalization, it is important to reduce the number of elderly
people passed away by Covid19 infection. Our findings could help
establish a triage system for vaccination in the long-term care
facilities for the elderly.”
Release URL:
https://www.eurekalert.org/news-releases/967037
Reference:
Poor vaccine responsiveness towards third-dose mRNA vaccine of COVID-19 in Japanese older people
Journal: Journal of Infection
DOI:10.1016/j.jinf.2022.07.007
Contact Person:Masanori Nakayama
Professor Masanori Nakayama is an independent group leader at the Max
Planck Institute for Heart and Lung Research Laboratory for Cell
Polarity and Organogenesis. He is also associated with the Office of
Innovative Medicine, Organization for Research Strategy and Development,
Okayama University, Japan. He has many research publications in reputed
journals to his credit.
https://www.okayama-u.ac.jp/eng/research_highlights/index_id171.html
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