![\"Study:](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/04\/ImageForNews_835209_17762168641843502.jpg\")
<\/a><\/p>\nStudy: Divergent inflammatory and neurology-related protein levels in long COVID following primary and breakthrough SARS-CoV-2 infections<\/a>. Image Credit: vectorfusionart \/ Shutterstock<\/p>\n In a recent study published in the journal\u00a0Communications Medicine<\/a>, researchers in Australia and Norway examined how inflammatory and neurological protein levels differ between long coronavirus disease 2019 (COVID-19) and recovery, and how they respond to vaccination and reinfection.<\/p>\n Long COVID Biomarker and Immune Dysregulation Background<\/p>\n According to research, an estimated 5% to 30% of people infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continue to experience symptoms months later, a condition known as long COVID.<\/p>\n Why do some people recover fully, but others suffer fatigue, brain fog, and chronic inflammation<\/a>? Some researchers think that their immune systems have become dysregulated and continue to react inappropriately; however, there are no conclusive biological markers that define this dysregulation.<\/p>\n Understanding these differences is critical for diagnosis and treatment, and how vaccination and reinfection influence these immune responses is also unclear. Further research is needed to identify reliable biomarkers and clarify long-term immune behavior in affected individuals.<\/p>\n Long COVID Proteomic Study Design<\/p>\n The present study was conducted on blood samples from participants in Victoria, Australia, enrolled in a longitudinal cohort. Patients were divided into three groups, namely healthy SARS-CoV-2-naive individuals, individuals who recovered from COVID-19, and people with long COVID.<\/p>\n Blood samples were collected 6 to 9 months after the initial infection and prior to vaccination.<\/p>\n A total of 182 inflammatory and neurology-related proteins were measured using multiplexed affinity proteomics through the Proximity Extension Assay platform. Researchers used a Luminex multiplex assay to measure immunoglobulin G (IgG) antibody levels against viral spike and nucleoproteins.<\/p>\n For longitudinal analysis, some participants provided additional samples two to four weeks after their third COVID-19 vaccine dose and after a breakthrough infection.<\/p>\n Machine learning analyses, including least absolute shrinkage and selection operator regression (LASSO) and Boruta feature selection, were utilized to identify candidate protein biomarkers.<\/p>\n Then, researchers used linear mixed-effects models to analyze how these protein levels changed over time.<\/p>\n All participants provided written informed consent, and ethical approval was obtained from institutional review boards to comply with research standards for the study.<\/p>\n Inflammatory Protein Differences in Long COVID<\/p>\n The study revealed protein patterns in this cohort that may help distinguish long COVID from both recovered and healthy individuals. Several inflammatory and neurological proteins were identified as key markers.<\/p>\n Notably, interleukin-20 (IL-20), macrophage chemoattractant protein-1 (MCP-1), and neuroblastoma suppressor of tumorigenicity 1 (NBL1) emerged as important discriminators of long COVID. Individuals with long COVID showed elevated IL-20 levels, suggesting ongoing inflammation even months after infection.<\/p>\n Comparisons between long COVID and healthy individuals identified additional proteins, including C-type lectin domain containing 10A (CLEC10A), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and hydroxyacylglutathione hydrolase (HAGH).<\/p>\n These findings highlight persistent immune alterations that may be relevant to symptoms such as fatigue and cognitive impairment.<\/p>\n Interestingly, recovered individuals with COVID-19 also showed protein differences compared with healthy individuals, indicating that immune alterations may persist after clinical recovery. For example, fibroblast growth factor 19 (FGF-19) and cystatin D (CST5) were associated with recovery status, suggesting that some immune changes may persist even after apparent recovery.<\/p>\n Vaccination, Reinfection, and Antibody Response Findings<\/p>\n Additionally, longitudinal analyses showed how the immune system responded after vaccination and after breakthrough infections. After a booster dose, all groups developed strong antibody responses, with high spike-specific IgG levels. However, following breakthrough infection, individuals with long COVID and those who had recovered exhibited lower spike-specific antibody levels compared to newly infected healthy individuals.<\/p>\n Changes in protein levels over time showed decreases in some markers, such as sirtuin 2 (SIRT2) and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), after reinfection compared with pre-vaccination levels. Importantly, the inflammatory patterns observed after initial infection were not replicated following reinfection in individuals with long COVID. This indicates that the immune system reacts differently upon re-exposure.<\/p>\n Another key observation was that vaccination did not worsen inflammation in individuals with long COVID, and the levels of inflammatory proteins either stabilized or decreased. However, the authors noted that the study was small and exploratory, and that these findings will need validation in larger cohorts.<\/p>\n Long COVID Biomarker Implications and Vaccination Tolerability<\/p>\n This study shows that, in this cohort, long COVID was associated with persistent and distinct immune alterations, particularly involving inflammatory and neurological proteins. It is also noted that vaccinations did not appear to exacerbate inflammatory or neurology-related protein responses in this cohort, thus providing additional support for the tolerability of vaccination in people with long COVID.<\/p>\n On the other hand, the immune response to reinfection differs from that triggered by the first infection, suggesting a potentially altered long-term immune response. The relevance of the findings is that they help researchers move one step closer to identifying candidate biomarkers that could eventually aid in diagnosing and treating long COVID.\u00a0<\/p>\n Understanding these immune signatures can inform future efforts to classify or monitor long COVID and support patients experiencing prolonged symptoms, ultimately improving long-term health outcomes in the post-pandemic world.<\/p>\n Journal reference:<\/p>\n Bansal, A., Olechnowicz, S. W., Kiernan-Walker, N., Cumming, J., Abdul Azeez, I., Mazhari, R., Cox, R. J., Mueller, I., Bowden, R., & Eriksson, E. M. (2026). Divergent inflammatory and neurology-related protein levels in long COVID following primary and breakthrough SARS-CoV-2 infections. Communications Medicine. DOI: 10.1038\/s43856-026-01541-6, https:\/\/www.nature.com\/articles\/s43856-026-01541-6<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Blood tests revealed protein patterns tied to long COVID months after infection, while booster shots did not appear…\n","protected":false},"author":2,"featured_media":379969,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[17609,13160,6781,4250,1596,32912,13448,2814,2815,3553,134,26947,6983,13346,3193,10271,111,139,69,2859,1518,13221,13222,13223,13224,13225,5390],"class_list":{"0":"post-379968","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health","8":"tag-antibody","9":"tag-assay","10":"tag-biomarker","11":"tag-blood","12":"tag-brain","13":"tag-brain-fog","14":"tag-chronic","15":"tag-coronavirus","16":"tag-covid-19","17":"tag-fatigue","18":"tag-health","19":"tag-immune-response","20":"tag-immune-system","21":"tag-inflammation","22":"tag-medicine","23":"tag-neurology","24":"tag-new-zealand","25":"tag-newzealand","26":"tag-nz","27":"tag-protein","28":"tag-research","29":"tag-respiratory","30":"tag-sars","31":"tag-sars-cov-2","32":"tag-severe-acute-respiratory","33":"tag-severe-acute-respiratory-syndrome","34":"tag-syndrome"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/379968","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=379968"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/379968\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/379969"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=379968"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=379968"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=379968"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}