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It is important to understand the correlates of protection against SARS-CoV-2 and its variants for future vaccine design. Here, the authors show that the complement system enhances the antibody-mediated neutralisation of SARS-CoV-2 via increased inhibition of virus-host interactions.

The authors characterize immune response in Omicron-infected vaccinated individuals and observe an immune enhancement. While increases in neutralizing antibodies and spike T cells are stronger in previously naïve individuals, mucosal antibodies and non-spike responses increase regardless of infection history.

The Omicron variant evades vaccine-induced neutralization but also fails to form syncytia, shows reduced replication in human lung cells and preferentially uses a TMPRSS2-independent cell entry pathway, which may contribute to enhanced replication in cells of the upper airway. Altered fusion and cell entry characteristics are linked to distinct regions of the Omicron spike protein.

Understanding the immune response to SARS-CoV-2 is dependent on being able to distinguish COVID-19 immune responses from cross-reactive immune responses to other coronaviruses. Here the authors show that choice of antigens and whether an ICS, ELISPOT or T cell proliferation assay is used has a major effect on this discriminatory ability.

Questions have arisen as to whether patients with severe COVID-19 disease can generate a T cell response against SARS-CoV-2. Tao Dong and colleagues report that convalescent patients with COVID-19 harbor functional memory CD4⁺ and CD8⁺ T cells that recognize multiple epitopes that span the viral proteome. CD4⁺ T cells predominated the memory response in patients with severe disease, whereas higher proportions of CD8⁺ T cells were found in patients with mild disease.

The engagement of immunological memory is a key component to the protective anti-SARS-CoV-2 B and T cell responses. Here the authors assess the B and T cells of a cohort of UK healthcare workers in response to infection and longitudinally track the compartment showing distinct trajectories following early priming.

Iron has been shown to be necessary for the activation and differentiation of CD8⁺ T cells. Here the authors investigate changes in CD8⁺ T cell metabolism in iron limiting conditions and find that aspartate is increased yet downstream nucleotide synthesis is suppressed and addition of exogenous aspartate partially rescues T cell function.

Due to the focus of vaccination on the SARS CoV-2 spike protein, spike has been associated with high levels of viral mutation and subsequent immune escape. Here the authors study a conserved epitope in SARS CoV-2 sub-domain-1 and characterise the neutralising antibody response and evasion in contemporary SARS COV-2 viral strains.

Many emerging SARS-CoV-2 variants partially escape the humoral immune response. Here, Liu et al. characterize 28 antibodies from BA.4/5 breakthrough infections and find attrition of neutralization and complete loss of function for variants with Spike mutations at positions 455 and 456.

A study demonstrates that nucleotide modifications in mRNA-based therapeutics can lead to +1 ribosomal frameshifting during translation, yielding products that can trigger immune responses.

Fine-scale geospatial mapping of overweight and wasting (two components of the double burden of malnutrition) in 105 LMICs shows that overweight has increased from 5.2% in 2000 to 6.0% in children under 5 in 2017. Although overall wasting decreased over the same period, most countries are not on track to meet the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025.

Serological analysis and infection outcomes of participants in the multi-center, prospectively enrolled OCTAVE cohort, comprising 2,686 participants with immune-suppressive diseases who recieved two COVID-19 vaccines, reveals specific clinical phenotypes that might benefit from specific COVID-19 therapeutic strategies.

Ragonnet-Cronin et al scanned SARS-CoV-2 genomes from >12,000 treated patients, identifying nine treatment-emergent mutations that increased in frequency after treatment with antibodies. In the laboratory, synthetic viruses harbouring those mutations escaped the antibodies, suggesting the mutations are driven by immune evasion.

Clarke and colleagues show that germinal center B cells have highly dynamic mitochondria, which are regulated by the transcription factor TFAM. TFAM activity is required to promote spatial entry into the germinal center reaction by modulating cellular motility.

Epidemiological analyses coupled with immunological phenotyping suggest that humoral immunity induced by COVID-19 vaccines wanes more rapidly in individuals with severe obesity compared to individuals with a BMI within the normal range.

Serological detection of antibodies against SARS-CoV-2 can help establish rates of seroconversion. Here the authors develop a red cell agglutination test to detect antibodies against the receptor binding domain for distribution free of charge to qualified research groups.

Understanding the effect of vaccination on emerging SARS-CoV-2 variants of concern is of increasing importance. Here, James et al. report that two doses of vaccination with the Pfizer-BioNTech vaccine induce more robust immune responses to the B.1.1.7 and B.1.351 SARS-CoV-2 lineages than does natural infection.

Although progress in the coverage of routine measles vaccination in children in low- and middle-income countries was made during 2000–2019, many countries remain far from the goal of 80% coverage in all districts by 2019.

Two doses of the coronavirus disease 2019 vaccine ChAdOx1 nCoV-19 boost antibody responses and functions in phase 1/2 trial participants.

In this Review, Meumann et al. discuss current knowledge on Burkholderia pseudomallei virulence and interaction with the host, and examine the epidemiology of melioidosis, offering insights into diagnosis, treatment and prevention strategies for this disease.

This Review discusses the evidence for pre-existing cross-reactive immune responses to SARS-CoV-2, which are mainly due to infections with common cold coronaviruses, and how such cross-reactivity affects adaptive immune responses. Furthermore, it explores cross-reactivity in the context of SARS-CoV-2 variants of concern and its implications for vaccine development.

Ertesvåg, Xiao et al. describe a method to evaluate neutralising antibodies to SARS-CoV-2 infection or vaccination, including variants of concern. A second mRNA-vaccine dose results in a broader antibody repertoire in adults, although with reduced cross-reactivity to beta and gamma compared to alpha and delta, particularly in the elderly.

A single dose of the ChAdOx1 nCoV-19 vaccine elicits antibodies and cytokine-producing T cells that might help control or prevent SARS-CoV-2 infection.