01/22—Fast-spreading COVID variant can elude immune responses
Fast-spreading COVID variant can elude immune responses
[Nature News report.] Evidence is growing that some coronavirus variants could evade immune responses triggered by vaccines and previous infections. “Some of the data I’ve seen in the last 48 hours have really scared me,” says Daniel Altmann, an immunologist at Imperial College London, who worries that some of results could portend a reduction in the effectiveness of COVID-19 vaccines.
Emergence of a Highly Fit SARS-CoV-2 Variant
The G614 variant replicated more efficiently than did the D614 variant in immortalized cells in culture and in primary human airway epithelial cells (Figure 1A and 1B). Even at D614-to-G614 variant infection ratios of 1:1, 3:1, or 9:1, the contemporary G614 strain outcompeted the ancestral D614 strain in primary human airway epithelial cells. The G614 variant also seemed to be more stable than the ancestral strain, which suggests that increased stability may be associated with increased infectivity.
Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection
We analyzed multiple compartments of circulating immune memory to SARS-CoV-2 in 254 samples from 188 COVID-19 cases, including 43 samples at ≥ 6 months post-infection. IgG to the Spike protein was relatively stable over 6+ months. Spike-specific memory B cells were more abundant at 6 months than at 1 month post symptom onset. SARS-CoV-2-specific CD4+ T cells and CD8+ T cells declined with a half-life of 3-5 months. By studying antibody, memory B cell, CD4+ T cell, and CD8+ T cell memory to SARS-CoV-2 in an integrated manner, we observed that each component of SARS-CoV-2 immune memory exhibited distinct kinetics.
The known unknowns of T cell immunity to COVID-19
Open questions about T cell immunity to SARS-CoV-2. Which host and viral factors regulate the strength and efficacy of the early antiviral T cell response? Is severe COVID-19 linked to an impaired development of SARS-CoV-2–specific memory T cells? Do preexisting memory T cells to seasonal coronavirus epitopes help or hinder the host response to SARS-CoV-2? What type of T cell response elicited by vaccines will be the best predictor of protection from disease after exposure to the virus?
Immunological characteristics govern the transition of COVID-19 to endemicity
Our analysis of immunological and epidemiological data on endemic human coronaviruses (HCoVs) shows that infection-blocking immunity wanes rapidly, but disease-reducing immunity is long-lived. Our model, incorporating these components of immunity, recapitulates both the current severity of CoV-2 and the benign nature of HCoVs, suggesting that once the endemic phase is reached and primary exposure is in childhood, CoV-2 may be no more virulent than the common cold.
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