Determinants of de novo B cell responses to drifted epitopes in post-vaccination SARS-CoV-2 infections (preprint)

Vaccine-induced immunity may impact subsequent de novo responses to drifted epitopes in SARS-CoV-2 variants, but this has been difficult to quantify due to the challenges in recruiting unvaccinated control groups whose first exposure to SARS-CoV-2 is a primary infection. Through local, statewide, and national SARS-CoV-2 testing programs, we were able to recruit cohorts of individuals who had recovered from either primary or post-vaccination infections by either the Delta or Omicron BA.1 variants. Regardless of variant, we observed greater Spike-specific and neutralizing antibody responses in post-vaccination infections than in those who were infected without prior vaccination. Through analysis of variant-specific memory B cells as markers of de novo responses, we observed that Delta and Omicron BA.1 infections led to a marked shift in immunodominance in which some drifted epitopes elicited minimal responses, even in primary infections. Prior immunity through vaccination had a small negative impact on these de novo responses, but this did not correlate with cross-reactive memory B cells, arguing against competitive inhibition of naive B cells. We conclude that dampened de novo B cell responses against drifted epitopes are mostly a function of altered immunodominance hierarchies that are apparent even in primary infections, with a more modest contribution from pre-existing immunity, perhaps due to accelerated antigen clearance.

No evidence that analgesic use after COVID-19 vaccination negatively impacts antibody responses (preprint)

Vaccines against SARS-CoV-2, the virus that causes COVID-19, showed high efficacy against symptomatic illness caused by the ancestral strain. Yet recent variants such as Omicron and its sublineages substantially escape vaccine-induced neutralizing antibodies. In response, bivalent mRNA booster vaccines updated to better match the BA.4-5 lineages have been made available. Yet the reactogenicity of these vaccines might negatively impact willingness to receive the booster immunization. While serious side effects following vaccination are rare, mRNA vaccines frequently lead to mild adverse events such as injection site pain, lymphadenopathy, myalgia, and fever. Over-the-counter analgesics might mitigate some of these mild adverse events, but animal models of SARS-CoV-2 infection have shown that non-steroidal anti-inflammatory drugs (NSAIDs) substantially reduce antiviral antibody responses, which are the best correlates of protection against COVID-19. It remains unknown whether these same inhibitory effects are seen in humans after mRNA vaccination. We surveyed 6,010 individuals who received COVID-19 vaccines regarding analgesic use and correlated these results with Spike-specific antibody levels. We found no negative impact of analgesic use on antibody levels, and in fact observed slightly elevated concentrations of anti-Spike antibodies in individuals who used painkillers. Logistic regression analyses demonstrated a higher proportion of those experiencing fatigue and muscle aches between NSAID users and those not taking pain medication, suggesting that the elevated antibody levels were likely associated with inflammation and mild adverse events rather than analgesic use per se. Together, our results suggest no detriment to painkiller use to alleviate symptoms after vaccination against COVID-19.

Competent immune responses to SARS-CoV-2 variants in older adults following mRNA vaccination (preprint)

Aging is associated with a reduced magnitude of primary immune responses to vaccination and constriction of immune receptor repertoire diversity. Clinical trials demonstrate high efficacy of mRNA based SARS-CoV-2 vaccines in older adults but concerns about virus variant escape have not been well addressed. We have conducted an in-depth analysis of humoral and cellular immunity against an early-pandemic viral isolate and compared that to the P.1. (Gamma) and B.1.617.2 (Delta) variants, as well to a B.1.595 SARS-CoV-2 isolate bearing Spike mutation E484Q, in <55 and >65 age cohorts of mRNA vaccine recipients. As reported, robust immunity required the second dose of vaccine. Older vaccine recipients exhibited an expected 3-5x reduction (but not a complete loss) in neutralizing antibody titers against both P.1. (Gamma) and the B.1.595 virus at the peak of the boosted response. However, older vaccinees manifest robust cellular immunity against early-pandemic SARS-CoV-2 and more recent variants, which remained statistically comparable to the adult group. While the duration of these immune responses remains to be determined over longer periods of time, these results provide reasons for optimism regarding vaccine protection of older adults against SARS-CoV-2 variants and inform thinking about boost vaccination with variant vaccines. eTOC summaryVaccine responses are often diminished with aging, but we found strong responses to SARS-CoV-2 in older adults following mRNA vaccination. T cell responses were not diminished when confronted by SARS-CoV-2 variants. Neutralizing Ab were reduced but not more than those in adults. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/453287v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@43f7fborg.highwire.dtl.DTLVardef@4d956aorg.highwire.dtl.DTLVardef@18c8d63org.highwire.dtl.DTLVardef@9677ff_HPS_FORMAT_FIGEXP M_FIG Created with BioRender.com C_FIG

Immune Responses to COVID-19 mRNA Vaccines in Patients with Solid Tumors on Active, Immunosuppressive Cancer Therapy (preprint)

Vaccines against SARS-CoV-2 have shown high efficacy, but immunocompromised participants were excluded from controlled clinical trials. We evaluated immune responses to the Pfizer/BioNTech mRNA vaccine in solid tumor patients (n=52) on active cytotoxic anti-cancer therapy. These responses were compared to a control cohort that also received the Pfizer/BioNTech vaccine (n=50). Using live SARS-CoV-2 assays, neutralizing antibodies were detected in 67% and 80% of cancer patients after the first and second immunizations, respectively, with a 3-fold increase in median titers after the booster. Similar trends were observed in serum antibodies against the receptor-binding domain (RBD) and S2 regions of Spike protein, and in IFN{gamma}+ Spike-specific T cells. The magnitude of each of these responses was diminished relative to the control cohort. We therefore quantified RBD- and Spike S1-specific memory B cell subsets as predictors of anamnestic responses to viral exposures or additional immunizations. After the second vaccination, Spike-specific plasma cell-biased memory B cells were observed in most cancer patients at levels similar to those of the control cohort after the first immunization. These data suggest that a third immunization might elevate antibody responses in cancer patients to levels seen in healthy individuals after the second dose. Trials should be conducted to test these predictions.

Group IIA Secreted Phospholipase A2 Plays a Central Role in the Pathobiology of COVID-19 (preprint)

There is an urgent need to identify cellular and molecular mechanisms responsible for severe COVID-19 disease accompanied by multiple organ failure and high mortality rates. Here, we performed untargeted/targeted lipidomics and focused biochemistry on 127 patient plasma samples, and showed high levels of circulating, enzymatically active secreted phospholipase A2 Group IIA (sPLA2-IIA) in severe and fatal COVID-19 disease compared with uninfected patients or mild illness. Machine learning demonstrated that sPLA2-IIA effectively stratifies severe from fatal COVID-19 disease. We further introduce a PLA-BUN index that combines sPLA2-IIA and blood urea nitrogen (BUN) threshold levels as a critical risk factor for mitochondrial dysfunction, sustained inflammatory injury and lethal COVID-19. With the availability of clinically tested inhibitors of sPLA2-IIA, our study opens the door to a precision intervention using indices discovered here to reduce COVID-19 mortality.

Detection, prevalence, and duration of humoral responses to SARS-CoV-2 under conditions of limited population exposure. (preprint)

We conducted an extensive serological study to quantify population-level exposure and define correlates of immunity against SARS-CoV-2. We found that relative to mild COVID-19 cases, individuals with severe disease exhibited elevated authentic virus-neutralizing titers and antibody levels against nucleocapsid (N) and the receptor binding domain (RBD) and the S2 region of spike protein. Unlike disease severity, age and sex played lesser roles in serological responses. All cases, including asymptomatic individuals, seroconverted by 2 weeks post-PCR confirmation. RBD- and S2-specific and neutralizing antibody titers remained elevated and stable for at least 2-3 months post-onset, whereas those against N were more variable with rapid declines in many samples. Testing of 5882 self-recruited members of the local community demonstrated that 1.24% of individuals showed antibody reactivity to RBD. However, 18% (13/73) of these putative seropositive samples failed to neutralize authentic SARS-CoV-2 virus. Each of the neutralizing, but only 1 of the non-neutralizing samples, also displayed potent reactivity to S2. Thus, inclusion of multiple independent assays markedly improved the accuracy of antibody tests in low seroprevalence communities and revealed differences in antibody kinetics depending on the viral antigen. In contrast to other reports, we conclude that immunity is durable for at least several months after SARS-CoV-2 infection.