Immunity to SARS-CoV-2: What Do We Know and Should We Be Testing for It?

Area of Science:

• Immunology
• Infectious Diseases
• Public Health

Background:

• Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic driven by lack of prior immunity, variant transmission, and vaccine challenges.
• Correlates of protection (CoP) are crucial for patient care and public health but difficult to establish.
• Neutralizing antibodies and cellular immunity are identified CoPs for COVID-19, arising from infection, vaccination, or hybrid immunity.

Purpose of the Study:

• To define Correlates of Protection (CoP) in the context of COVID-19.
• To review current understanding of immunity induced by SARS-CoV-2 infection, vaccination, and hybrid immunity.
• To summarize the utility of SARS-CoV-2 serologic testing for assessing immunity.

Main Methods:

• Review of existing scientific literature on SARS-CoV-2 immunity and correlates of protection.
• Analysis of challenges in serologic assay standardization and variant immune evasion.
• Discussion of the role of neutralizing antibodies and adaptive cellular immune responses.

Main Results:

• Neutralizing antibodies and cellular immunity are established CoPs for COVID-19.
• Challenges include assay diversity, lack of standardization, and SARS-CoV-2 variant immune evasion.
• Determining a robust CoP threshold and routine 'immunity' documentation is hindered.

Conclusions:

• Understanding CoPs is vital for managing COVID-19 and future pandemics.
• Standardization of serologic assays is needed for reliable assessment of SARS-CoV-2 immunity.
• Future utility of serologic testing depends on addressing current limitations and variant evolution.