Cross-Variant Neutralizing Serum Activity after SARS-CoV-2 Breakthrough Infections

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants pose a significant public health challenge.
• Breakthrough infections after vaccination can elicit immune responses.
• Understanding neutralizing activity is crucial for assessing vaccine effectiveness against evolving viral strains.

Purpose of the Study:

• To evaluate the neutralizing antibody activity in individuals experiencing breakthrough SARS-CoV-2 infection.
• To compare cross-variant neutralizing activity with responses after a 3-dose vaccination regimen.
• To investigate the relationship between vaccination-to-infection intervals and neutralizing titers.

Main Methods:

• Serum samples were collected from 30 individuals with breakthrough SARS-CoV-2 infection following a 2-dose vaccination.
• Neutralizing activity was assessed against the SARS-CoV-2 ancestral strain and four variants of concern.
• Statistical analysis was performed to correlate intervals with neutralizing titers.

Main Results:

• Cross-variant neutralizing activity in breakthrough infections was comparable to that observed after 3-dose vaccination.
• Individuals with shorter intervals between vaccination and breakthrough infection exhibited lower neutralizing antibody titers.
• The study demonstrated robust neutralizing capacity even after only 2 vaccine doses followed by infection.

Conclusions:

• Two-dose vaccination followed by breakthrough infection generates cross-variant neutralizing activity comparable to three-dose vaccination.
• Immune imprinting or waning immunity, indicated by shorter vaccination-to-infection intervals, may influence neutralizing antibody levels.
• These findings have implications for understanding vaccine effectiveness and informing public health strategies against SARS-CoV-2.