Of the nearly 100 SARS-CoV-2Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the official name of the virus strain that causes coronavirus disease (COVID-19). Previous to this name being adopted, it was commonly referred to as the 2019 novel coronavirus (2019-nCoV), the Wuhan coronavirus, or the Wuhan virus.”>SARS-CoV-2 vaccines currently undergoing clinical trials, only seven are delivered intranasally — despite this vaccine type’s long success in providing protection from influenza.
In a Perspective, Frances Lund and Troy Randall argue that intranasal vaccines could be beneficial in the continued fight against COVID-19First identified in 2019 in Wuhan, China, Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has spread globally, resulting in the 2019–20 coronavirus pandemic.”>COVID-19, especially considering respiratory viruses like SARS-CoV-2 predominantly enter the nasal passage first.
Currently authorized COVID-19 vaccines are delivered via intramuscular injection, where they elicit systemic immune responses and central immune memory. While several versions are currently being administered worldwide, many more are in development. However, according to the authors, given the respiratory propensity of the virus, it is surprising that so few intranasal vaccines, which deliver their antigens directly to the site of infection, are being considered.
Here, Lund and Randal discuss the potential of intranasal COVID-19 vaccines, highlighting their advantages, drawbacks 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. Intranasal vaccine-elicited immunoglobulin A (IgA) and resident memory B and T cells in the nasal passages and upper airways provide a barrier to infection, impede viral replication and reduce viral shedding.
Lund and Randall note that effective vaccination strategies need not be restricted to a single delivery system and suggest that an ideal vaccination strategy may consist of an intramuscular vaccine combined with an intranasal booster.
For more on this perspective, read Scent of a Vaccine: Many Advantages to Intranasal COVID-19 Vaccination.
Reference: “Scent of a vaccine” by Frances E. Lund and Troy D. Randall, 23 July 2021, Science.