A new study published in one of the world’s leading scientific journals: Cell by researchers from the department of pathology at Stanford University, California-USA has alarmingly found that mRNA jab generated spike proteins circulate in blood and persist for months in lymph nodes
One of the positive developments amid the global calamity of the SARS-CoV-2 pandemic has been the rapid design, production and deployment of a variety of vaccines, including remarkably effective mRNA vaccines encoding the viral spike (Baden et al., 2021; Polack et al., 2020).
We find that BNT162b2 vaccination produces IgG responses to spike and RBD at concentrations as high as those of severely ill COVID-19 patients and follows a similar time course. Unlike infection,which stimulates robust but short-lived IgM and IgA responses, vaccination shows a pronounced bias for IgG production even at early time points. These responses were similar across the adult age range in our study.
The relative absence of IgM and IgA responses suggests a potent effect of the vaccine formulation in driving early and extensive IgG class-switching, potentially as a result of the reported T helper type 1-polarized CD4+ T cell responses stimulated by vaccine components (Lederer et al., 2020; Lindgren et al., 2017; Pardi et al., 2018).
Our data demonstrate that vaccinee plasma and saliva spike and RBD-specific IgG concentrations decrease from their peak values by approximately 20-fold by 9 months after primary vaccination, but quickly exceed prior peak concentrations in 7 to 8 days after boosting with a 3rd vaccine dose.
Correlates of immunological protection from SARS-CoV-2 infection following vaccination or prior infection are still under investigation. Analysis of Moderna mRNA-1273 and AstraZeneca ChAdOx1-S responses highlights the overall similarity of correlate of protection results for spike- binding antibody and neutralizing antibody assays (Feng et al., 2021; Gilbert et al., 2022).
We compared spike or RBD-binding antibody responses to Wuhan-Hu-1 SARS-CoV-2 neutralization data in BNT162b2 vaccinees and confirmed the high correlation of these assay results, supporting the interpretation that sensitive, precise and validated commercial multiplexed antigen-binding assays with a wide dynamic range, such as the MSD ECL assays in this study, will be valuable in providing standardized correlates of protection data for vaccines as the pandemic continues. Particularly in the context of viral variants, it will be important to determine whether predictions of vulnerability to infection or severe disease can be improved by adding data from other immunological assays, including T cell measurements.
Differences in B cell responses to SARS-CoV-2 infection and vaccination may be reflected in the binding breadth of antibodies to different SARS-CoV-2 variants. We find that plasma of individuals who received prime/boost BNT162b2 vaccination, as well as individuals who received adenoviral vectored (ChAdOx1-S or Gam-COVID-Vac) or inactivated virus (BBIBP-CorV) COVID-19 vaccines show consistent patterns of binding to variant RBDs with modest decreases compared to Wuhan-Hu-1 RBD binding.
In contrast, COVID-19 patients produce antibody responses with significantly greater Wuhan-Hu-1 RBD binding preference and lower breadth of variant RBD binding. These differences between vaccinee and COVID-19 patient IgG variant antigen binding were greatest for the RBD, the target of most neutralizing antibodies, and were diminished when full spike antigen with its greater number of non-neutralizing epitopes was tested.
These results, covering many clinically relevant viral variant antigens and several vaccine modalities, are consistent with findings for RBD binding IgG in mRNA-1273 vaccinees compared to infected patients (Greaney et al., 2021b). Notably, COVID-19 patients with Alpha or Delta variant infections display characteristic serological profiles specific to the RBD of the infecting variant, indicating that SARS-CoV-2 variant serotyping may be useful for epidemiological studies of populations to determine exposure to circulating SARS-CoV-2 variants.
Both vaccinees and COVID-19 patients exposed to Wuhan-Hu-1 antigens show the greatest decreases in antibody binding to RBD variants harboring E484 alterations, including Beta and Gamma. Although susceptibility to infection by viral variants is common to both vaccinated and convalescent populations, particularly as antibody titers decrease over time (Israel et al., 2021; Levin et al., 2021), our findings lead to the prediction that antibodies derived from infection may provide somewhat decreased protection against virus variants compared to comparable concentrations of antibodies stimulated by vaccination.
As additional variants of SARS-CoV-2 appear over time, individuals will acquire distinct immunological histories depending on which vaccines they received and which viral variants infected them. The idea that “imprinting” by a prior antigen exposure can shape, either positively or negatively, the response to a subsequent variant is well established in studies of influenza viruses, and has been implicated in birth-year differences in susceptibility to particular avian influenza viruses (Gostic et al., 2016).
We find that prior vaccination with Wuhan-Hu-1-like antigens followed by infection with Alpha or Delta variants gives rise to plasma antibody responses with apparent Wuhan-Hu-1-specific imprinting manifesting as relatively decreased responses to the variant virus epitopes, compared to unvaccinated patients infected with those variant viruses.
While current booster vaccinations are still based on the Wuhan-Hu-1-like antigens, vaccine manufacturers are in the process of evaluating updated vaccines encoding sequences from one or more circulating variants. Initial results from 3rd dose boosting with Beta spike-encoding mRNA vaccines after prior 2-dose mRNA-1273 vaccination are consistent with our findings of significant imprinting of serological responses by the first antigen encountered (Choi et al., 2021; Chu et al., 2021), indicating that vaccine-derived imprinting affects subsequent antibody responses stimulated by vaccination as well as infection.
The extent to which vaccine boosting or infection with different variants will effectively elicit antibody responses to new epitopes, or rather increase responses to the epitopes of antigens encountered previously, as in the “original antigenic sin” phenomenon described for influenza virus infection and vaccination (Arevalo et al., 2020; Zhang et al., 2019), will be an important topic of ongoing study. The degree of imprinting may depend on the particular variants and the order in which they are introduced to the individual’s immune system, and the number of exposures, such as the number of vaccine doses received.
Additional data for evaluating the magnitude of these effects and their consequences for protection from infection are likely to become available in coming months, as individuals with different histories of SARS-CoV-2 vaccination or viral variant infection become infected with the more highly mutated Omicron variant (https://covdb.stanford.edu/page/mutation- viewer/#omicron).
As a practical consideration, the very high spike-specific IgG concentrations generated by mRNA vaccination and periodic additional booster doses may be able to compensate for relatively decreased binding to new viral variant antigens, potentially decreasing the public health impact of antibody response imprinting if vaccine boosting is widely adopted.
We hypothesized that differences in the serological responses observed in SARS-CoV-2 infection compared to vaccination, particularly those related to variant antigen binding breadth, could be related to the anatomical sites where the viral antigens are encountered, the quantity of viral antigens in those anatomical sites, differences in the cell populations stimulated in secondary lymphoid tissues, and potential damage to immunological tissues during infection.
With CODEX multiplexed immunofluorescence microscopy and immunohistochemical microscopy, we identified follicular hyperplasia with robust axillary LN GCs after mRNA (BNT162b2 or mRNA- 1273) vaccination, containing CD21+ follicular dendritic cell networks, BCL6+ B cells and PD-1+ cells at significantly higher frequencies compared to those in peribronchial LNs of deceased COVID-19 patients.
These findings demonstrate greater stimulation of GC B cells and Tfh cells in vaccination, and normal functional organization of GC follicular dendritic cells. Loss or impairment of GCs in patients with severe COVID-19 suggests that SARS-CoV-2 viral infection subverts the humoral immune response, by directly damaging immune cells or as a secondary effect of inflammatory responses to infection (Feng et al., 2020; Kaneko et al., 2020).
The observed extended presence of vaccine mRNA and spike protein in vaccinee LN GCs for up to 2 months after vaccination was in contrast to rare foci of viral spike protein in COVID-19 patient LNs. We hypothesize that the abundant spike antigen in the GCs of mRNA vaccine recipient LNs may contribute to the increased breadth of viral variant RBD binding by IgG seen after vaccination, potentially due to high antigen concentrations stimulating B cells with lower affinity for Wuhan- Hu-1 spike epitopes and better binding to variant epitopes.
Persistent vaccine RNA and spike antigen at elevated concentrations in vaccinee LNs could result in less strict selection for higher- affinity B cells in the immune response compared to situations where antigen is more limiting (Cirelli et al., 2019). However, our observation that all vaccine modalities (mRNA, adenoviral and inactivated virus) stimulated greater viral variant breadth of IgG binding than infection could indicate that some other aspect of SARS-CoV-2 infection underlies these differences, such as alteration of GC function.
Pre-pandemic analysis of a model RNA vaccine for yellow fever virus in a rhesus macaque at 16 hours post-vaccination showed that vaccine RNA in LN cell suspensions was detected predominantly in professional antigen-presenting cells including monocytes, classical dendritic cells and B cells at this early time point (Lindsay et al., 2019). Data from follicular dendritic cells were not reported.
Our histological data from SARS-CoV-2 mRNA-vaccinated humans at considerably later time points (7 to 60 days post-2nd dose) show vaccine RNA almost entirely in GCs, distributed primarily between the nuclei of GC cells, similar to the pattern seen by immunostaining for follicular dendritic cell processes or B cell cytoplasm. Additional co- localization studies with higher resolution may be required to determine more exactly which specific cell types harbor mRNA vaccine and spike antigen in humans following COVID-19
mRNA vaccination and infection, and may provide further mechanistic insights into the basis for the differences in serological responses after vaccination compared to infection.
At least some portion of spike antigen generated after administration of BNT162b2 becomes distributed into the blood. We detected spike antigen in 96% of vaccinees in plasma collected one to two days after the prime injection, with antigen levels reaching as high as 174 pg/mL.
The range of spike antigen concentrations in the blood of vaccinees at this early time point largely overlaps with the range of spike antigen concentrations reported in plasma in a study of acute infection (Ogata et al., 2020), although a small number of infected individuals had higher concentrations in the ng/mL range. At later time points after vaccination, the concentrations of spike antigen in blood quickly decrease, although spike is still detectable in plasma in 63% of vaccinees one week after the first dose.
A practical finding in our study is that the detection of spike antigen in plasma samples is impeded after 2nd dose BNT162b2 vaccination, likely due to the formation of circulating immune complexes of anti-spike antibodies and spike protein, masking the antigen epitopes of the capture and detection antibodies that form the basis of antigen detection assays, similar to assay interference that has been reported for other diseases (Bollinger et al., 1992; Lima et al., 2014; Miles et al., 1993).