Mucosal immunity: The missing link in comprehending SARS-CoV-2 infection and transmission

Area of Science:

• Immunology
• Virology
• Vaccinology

Background:

• SARS-CoV-2 causes COVID-19, primarily infecting the upper respiratory tract.
• Mucosal immune responses, including secretory IgA (SIgA) antibodies, are induced early in infection.
• Current injectable vaccines prevent severe disease but may not elicit strong mucosal immunity.

Purpose of the Study:

• To explore the potential of intranasal vaccines in inducing mucosal immunity against SARS-CoV-2.
• To compare the efficacy of intranasal versus injectable vaccines in generating SIgA responses.

Main Methods:

• Review of existing evidence on SARS-CoV-2 infection and immune responses.
• Analysis of studies on intranasal and injectable COVID-19 vaccine efficacy.
• Focus on the induction of secretory IgA (SIgA) antibodies in mucosal secretions.

Main Results:

• Intranasal administration of vaccines has shown promise in animal models for inducing mucosal immunity.
• Injectable vaccines primarily induce systemic immunity, with limited SIgA recall in previously infected individuals.
• Intranasal vaccines have the potential to induce SIgA in respiratory and oral secretions.

Conclusions:

• Intranasal vaccines could provide a distinct advantage in preventing SARS-CoV-2 acquisition and transmission.
• Induction of mucosal SIgA antibodies may be key to limiting upper respiratory tract infections and community spread.
• Further research is needed to confirm the efficacy of intranasal COVID-19 vaccines in humans.