Advantages of intranasal vaccination against SARS-CoV-2
Intranasal vaccination is needle-free and elicits immunity at the site of infection, the respiratory tract

Date:
July 23, 2021
Source:
University of Alabama at Birmingham
Summary:
There are many reasons that an intranasal vaccine against the
SARS-CoV- 2 virus would be helpful in the fight against COVID-19
infections, immunologists write in a new article.



FULL STORY ========================================================================== There are many reasons that an intranasal vaccine against the SARS-CoV-2
virus would be helpful in the fight against COVID-19 infections,
University of Alabama at Birmingham immunologists Fran Lund, Ph.D., and
Troy Randall, Ph.D., write in a viewpoint article in the journal Science.


==========================================================================
That route of vaccination gives two additional layers of protection
over intramuscular shots because it produces: 1) immunoglobulin A and
resident memory B and T cells in the respiratory mucosa that are an
effective barrier to infection at those sites, and 2) cross-reactive
resident memory B and T cells that can respond earlier than other immune
cells if a viral variant does start an infection.

"Given the respiratory tropism of the virus, it seems surprising that
only seven of the nearly 100 SARS-CoV-2 vaccines currently in clinical
trials are delivered intranasally," Lund and Randall said. "Advantages
of intranasal vaccines include needle-free administration, delivery of
antigen to the site of infection, and the elicitation of mucosal immunity
in the respiratory tract." Their viewpoint article goes on to detail
the individual advantages and challenges of each of the seven intranasal vaccine candidates. Six are viral vectors, including three different
adenovirus vectors, and one candidate each for live-attenuated influenza
virus, live-attenuated respiratory syncytial virus and live-attenuated SARS-CoV-2. The seventh vaccine candidate is an inert protein subunit.

Among the drawbacks of using viruses that people may have encountered
before is negative interference from anti-vector antibodies that impair
vaccine delivery.

And because of the minimal risk of reversion for the live-attenuated
SARS-CoV- 2 virus, it would likely be contraindicated for infants,
people over 49 and immunocompromised persons.

"Notably absent from the list of intranasal vaccines are those formulated
as lipid-encapsulated mRNA," Lund and Randall said, listing some of the challenges and adverse side effects that accompany that approach.

"Ultimately, the goal of vaccination is to elicit long-lived protective immunity," the UAB researchers concluded. Comparing the benefits
and disadvantages of intranasal vaccination against intramuscular
vaccinations, they suggest that perhaps effective vaccination need not
be restricted to a single route.

"The ideal vaccination strategy," the immunologists concluded,
"may use an intramuscular vaccine to elicit a long-lived systemic immunoglobulin G response and a broad repertoire of central memory B and
T cells, followed by an intranasal booster that recruits memory B and
T cells to the nasal passages and further guides their differentiation
toward mucosal protection, including immunoglobulin A secretion and tissue-resident memory cells in the respiratory tract." At UAB, Lund
is a professor of microbiology and holds the Charles H. McCauley Chair
of Microbiology. Randall is a professor of medicine in the Division of
Clinical Immunology and Rheumatology, and he holds the Meyer Foundation
William J. Koopman, M.D., Endowed Chair in Immunology and Rheumatology.

========================================================================== Story Source: Materials provided by
University_of_Alabama_at_Birmingham. Original written by Jeff
Hansen. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Frances E. Lund, Troy D. Randall. Scent of a vaccine. Science,
2021; 373
(6553): 397 DOI: 10.1126/science.abg9857 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210723130849.htm

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