Advantages of Intranasal COVID-19 Vaccinations Over Injections

Of the nearly 100 SARS-CoV-2 vaccines currently undergoing clinical trials, only seven are delivered intranasally — despite this vaccine type’s long-standing success in providing protection against flu.

In one perspective, Frances Lund and Troy Randall argue that intranasal vaccines could be beneficial in the ongoing battle against COVID-19, especially considering that respiratory viruses such as SARS-CoV-2 primarily enter the nasal cavity first.

Currently authorized COVID-19 vaccines are administered via intramuscular injection, where they elicit systemic immune responses and central immune memory. While several versions are currently being managed worldwide, many more are in development. However, given the respiratory propensity of the virus, it is surprising, according to the authors, that so few intranasal vaccines are considered that deliver their antigens directly to the site of infection.

Here, Lund and Randal discuss the potential of intranasal COVID-19 vaccines, highlighting their advantages, disadvantages and rationale for use over intramuscular options. In addition to being needle-free, intranasal vaccines provide two additional layers of protection compared to intramuscular vaccines. Intranasally vaccine-evoked immunoglobulin A (IgA) and resident memory B and T cells in the nasal passages and upper respiratory tract form a barrier against infection, impede viral replication and reduce viral shedding.

Lund and Randall note that effective vaccination strategies need not be limited to a single delivery system and suggest that an ideal vaccination strategy may consist of an intramuscular vaccine combined with an intranasal booster.

To learn more about this perspective, read Smell of a Vaccine: Many Benefits of Intranasal COVID-19 Vaccination.

Reference: “Scent of a vaccine” by Frances E. Lund and Troy D. Randall, July 23, 2021, Science.
DOI: 10.1126/science.abg9857