Immune 66: COVID-19 immune memory - what you need to know
Apr 4, 2023
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Immunology experts discuss immune memory to SARS-CoV-2 and COVID-19 vaccines, emphasizing CD8 T cells' role, different vaccine responses, epitope recognition, B cell longevity, booster efficacy debates, ethical obligations of billionaires, and the importance of knowledge sharing for vaccine development.
Memory CD8 T cells provide long-term immunity post-SARS-CoV-2 infection.
B cell memory against future variants is long-lasting and influenced by disease severity.
Hybrid immunity from vaccination and infection enhances memory responses and neutralizing antibodies.
Deep dives
Robust Immune Memory to SARS-CoV-2: Insights from Podcast Episode
The immune response to SARS-CoV-2 infection and vaccines has established benchmark levels of memory in human immunology, with extensive data on human antigen-specific immune responses. Studies indicate a significant presence of memory CD8 T cells providing long-term memory against the virus, lasting notably over 6 months, even showing potential for years. The hybrid immunity from vaccination and infection demonstrates similarities in generating memory responses, with a notable presence of spike-specific memory CD8 T cells in individuals over time.
Durable T Cell Memory with Variants
T cell memory longevity and specificity remain key features post-infection, with a median recognition of 17 epitopes per individual, primarily targeting conserved structural proteins. Hybrid immunity showcases moderate differences between vaccination alone and combined immunity, indicating potential advantages for robust memory cell responses. Cross-reactive T cell responses to common cold coronaviruses may offer some level of protection, albeit biological relevance is under scrutiny.
B Cell Memory Development and Variability
B cell memory is affirmed to be long-lasting, providing immunity against future variants. Infection triggers detectable B memory cells within 2 weeks, with sustained increases over 3 to 6 months post-infection, impacting virus neutralization potency and affinity. Severity of disease influences memory cell magnitude, with hospitalized individuals showcasing higher B memory cells compared to those with mild COVID, while asymptomatic cases also exhibit robust memory responses.
Impressive Memory Responses and Cellular Interactions
The immune system demonstrates brilliance in predicting viral mutations through memory B cell libraries, essential for combating variants. Infection elicits diverse memory cell responses, including CD8 T cells recognizing spike-specific epitopes over time. The interplay of memory T and B cells showcases a comprehensive and persistent immune defense against SARS-CoV-2, shaping immunity post-infection and vaccination.
Vaccination and RNA Vaccines
Two dose mRNA vaccines result in substantial B memory cells, though qualitatively poorer than after infection. Neutralizing antibodies improve months after infection, not after RNA vaccination, possibly due to timing between doses affecting maturation.
Hybrid Immunity and B Cell Memory
Hybrid immunity leads to substantial increase in BDIG B memory cells compared to vaccination alone, with enhanced somatic hypermutation and affinity maturation. Neutralizing antibody titers remain stable between four to six months, showing higher durability and efficacy against variants.
Immune discusses the current understanding of immune memory to SARS-CoV-2 infection and COVID-19 vaccines, which supersedes that of any other acute infectious disease.
