SARS-CoV-2-Specific Immune Responses in Vaccination and Infection during the Pandemic in 2020-2022

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Understanding SARS-CoV-2 immunity is crucial for vaccine development and public health strategies.
• Immune responses vary between natural infection and vaccination, impacting long-term protection.

Purpose of the Study:

• To analyze SARS-CoV-2 specific immune responses (IgG, IgA, T-cells) following infection and vaccination.
• To compare the durability and effectiveness of natural versus vaccine-induced immunity.
• To investigate mucosal immunity's role in protection.

Main Methods:

• Analysis of serum and saliva samples for receptor-binding domain (RBD) and nucleocapsid (N)-specific IgG and IgA antibodies.
• Assessment of N-specific T-cell responses (IFN-γ, CD107a).
• Longitudinal monitoring of immune markers post-infection and post-vaccination.

Main Results:

• mRNA vaccination boosted anti-RBD IgG levels higher than natural infection in one case.
• Vaccine-induced anti-RBD IgG declined after six months, with boosters providing temporary increases.
• N-specific T-cell responses were transient, detected only early after infection.
• Salivary IgA responses were generally undetectable, with transient peaks observed early post-infection.

Conclusions:

• SARS-CoV-2 infection induces expected immune responses, but antibody levels may wane over time.
• Current intramuscular vaccines induce detectable IgG, but levels decline.
• Early mucosal immune responses during infection might offer superior protection compared to intramuscular vaccines.