Although COVID-19 booster vaccinations in adults elicit high levels of neutralizing antibodies against the Omicron variant of SARS-CoV-2, antibody levels decrease substantially within 3 months, according to new clinical trial data.
From: NIH/National Institute of Allergy and
Infectious Diseases
July 19, 2022 -- The
findings, published today in Cell Reports Medicine, are from a
study sponsored by the National Institute of Allergy and Infectious Diseases
(NIAID), part of the National Institutes of Health. The trial was led by
NIAID's Infectious Diseases Clinical Research Consortium.
As part of a "mix
and match" clinical trial, investigators administered COVID-19 booster
vaccines to adults in the United States who had previously received a primary
COVID-19 vaccination series under Emergency Use Authorization. Some
participants received the same vaccine as their primary series, and others
received a different vaccine. Investigators then evaluated immune responses
over time. Results previously reported in The New England Journal of
Medicine showed all combinations of primary and booster vaccines
resulted in increased neutralizing antibody levels in the recipients.
In the new analysis,
investigators report that nearly all vaccine combinations evaluated (see table)
elicited high levels of neutralizing antibodies to the Omicron BA.1
sub-lineage. However, antibody levels against Omicron were low in the group
that received Ad26.COV2.S as both a primary vaccine and boost. Moreover, immune
responses to Omicron in all groups waned substantially, with neutralizing antibody
levels decreasing 2.4- to 5.3-fold by three months post-boost. Omicron
sub-lineages BA.2.12.1 and BA.4/BA.5 were 1.5 and 2.5 times less susceptible to
neutralization, respectively, compared to the BA.1 sub-lineage, and 7.5 and
12.4 times less susceptible relative to the ancestral D614G strain. BA.5
currently is the dominant variant in the U.S.
The authors note that
the findings are consistent with real-world reports showing waning protection
against SARS-CoV-2 infection during the Omicron wave in people who received a
primary vaccine series plus a booster shot. Additionally, the immune response
to Omicron sub-lineages show reduced susceptibility to these rapidly emerging
subvariants. The data could be used to inform decisions regarding future vaccine
schedule recommendations, including the need for variant vaccine boosting.
https://www.sciencedaily.com/releases/2022/07/220719162112.htm
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