Yale LISTEN Study – Listen to Immune, Symptom and Treatment Experiences Now

Based on both self-reports and serological analyses the participants were classified into four subgroups,

1. Post Vaccine Syndrome with no history of Covid-19 infection (PVS-I)
2. Post Vaccine Syndrome with a history of Covid-19 infection (PVS+I),
3. Control group with no history of Covid-19 infection (Control-I) and
4. Control group with a history of Covid-19 infection (Control+I).

Even though all PVS participants developed chronic symptoms following vaccination and not infection, it was important to consider the impact of a subsequent SARS-CoV-2 infection on immune phenotypes analyzed in this study.

The researchers noted that compared with controls, PVS participants exhibited differences in immune profiles, including

• reduced circulating memory and effector CD4 T cells (type 1 and type 2) and an
• increase in TNFα+ CD8 T cells.
• PVS participants also had lower anti-spike antibody titers, primarily due to having received fewer vaccine doses than controls.
• Serological evidence of recent Epstein-Barr virus (EBV) reactivation was observed more frequently in PVS
  participants. Further, individuals with PVS exhibited elevated levels of circulating spike
  protein compared to healthy controls.

These findings reveal potential immune differences in individuals with PVS from those with Long Covid, that merit further investigation to better understand this condition and inform future research into diagnostic and therapeutic approaches.

Some individuals reported post-vaccination symptoms resembling long COVID beginning shortly after vaccination. This condition, sometimes referred to as post-vaccination syndrome (PVS) or post-acute COVID-19 vaccination syndrome (PACVS), is characterized by symptoms such as

• exercise intolerance,
• excessive fatigue,
• numbness,
• brain fog,
• neuropathy,
• insomnia,
• palpitations,
• myalgia,
• tinnitus or humming in ears,
• headache,
• burning sensations, and
• dizziness.

In the non-reactive to vaccination group, the antibody indices varied between 0.09 and 0.17, whereas in the reactive to vaccination group, they ranged between 1.37 and 94.4, which is clearly a very significant difference.

Most individuals in each cohort completed the primary series of vaccines based on
WHO recommendations (83.3%, PVS; 100%, Controls). Participants with PVS received significantly fewer COVID-19 vaccine doses compared with controls, due to the reactions post vaccine administration.

On similar lines, the median number of days post the latest vaccination was significantly higher among PVS cases, with a median of 585 days, compared with 199 days among controls.

In 85% of the cases, participants identified the index vaccine dose as being part of the primary series [dose
1 (45%) and dose 2 (40%). The median number of days for the development of any symptom was 4, while for severe symptoms, it was 10 days post-vaccination.

A high proportion of participants with PVS developed any symptoms (70%) or severe symptoms (52.2%) within 10 days of vaccination.

Given the differences in the number of vaccine doses received between participants in the PVS cohort and the control group, we compared spike-specific immunoglobulin G (IgG) levels in relation to the number of vaccine doses administered.

Correlation analyses revealed a significant positive correlation between the number of vaccine doses and plasma anti-Spike IgG levels, as well as anti-RBD (Receptor Binding Domain) IgG levels in the PVS-I (no Covid infection) subgroup.

In the PVS+I (prior Covid infection) subgroup, only anti-Spike IgG levels showed a significant correlation with the number of doses.

Next, correlation analyses were performed to assess the relationships between plasma anti-S, anti-RBD, and anti-N (Nuclear) IgG levels with the number of days post last vaccination among the four groups.

No significant changes in anti-S and anti-RBD antibody levels were observed with
increasing days since vaccination in the control group, regardless of infection history,
and also in the PVS+I (plus infection) subgroup.

In contrast, significant negative correlations were found in the PVS-I subgroup between the number of days post-vaccination and both anti-Spike and anti-RBD IgG levels, indicating a decline in these antibodies over time. Additionally, as expected, no correlations were observed between anti-N IgG levels and days post vaccination across the infection-positive subgroups.

In this study, researchers examined symptoms and circulating immune factors and cell types associated with chronic illness following COVID-19 vaccination.

Post-acute conditions following COVID-19 vaccination have been reported for multiple vaccine platforms
including mRNA and adenoviral-vectored vaccines.

The general health status of the PVS (Post Vaccine Syndrome) participants was far below the general US population average.

The patient-reported outcome scores from the PROMIS29 domains were also indicative of lower quality of life. A large percentage of individuals reported the onset of symptoms to be as early as within one day of COVID-
19 vaccination.

1. Compared with controls, participants with PVS had reduced CD4+ T cell subsets in circulation (both Th1 and Th2) and an increased percentage of TNFα+ CD8 T cells.
2. Among cell populations of myeloid origin, cDC2 cells were reduced, and non-
   classical monocytes were elevated among PVS participants.
3. Lower S-specific IgG levels were observed in PVS mainly due to the limited vaccine doses received.
4. Additionally, serological evidence for recent EBV reactivation was also observed.
5. Using machine learning approaches, we further identified a set of 21 core predictive features
   of PVS status within the LISTEN PVS cohort with potential for further validation and
   biomarker identification.
6. Most notably, we found elevated levels of spike (S1 and full-length S) in circulation up to 709 days after vaccination among a subset with PVS, even in those with no evidence of detectable SARS-CoV-2 infection.

Previous studies on PVS have found the presence of elevated levels of inflammatory cytokines such as CCL5, IL-6, and IL-8; IgG subclass imbalances, high angiotensin II type 1 receptor antibodies (AT1R), and the presence of spike S1 in non-classical monocytes, among others.

In the LISTEN PVS cohort, there was no evidence of elevation in inflammatory cytokines or IgG subclass imbalances. This difference may be due to the heterogeneity of the cohorts studied, vaccine types or the time from vaccination.

The demographics at risk of developing PVS and symptom manifestations are similar to those of long COVID. Whether this reflects overlapping underlying mechanisms such as persistent S protein remains to be determined. Circulating S1 antigen has been detected in mRNA-1273 vaccine recipients without a prior history of viral infection within an average of five days after the first injection and becomes undetectable by day 1416.

By contrast, in this study, significantly elevated levels of circulating S1 and S were observed in a subset of PVS participants both in the infection-naive and infection-positive groups up to 709 days post-exposure.

This is in line with the findings of S1 persistence in monocytes in people with PVS. Circulating full-length S
has also been detected in cases of post-vaccination myocarditis.

Given the striking similarities between long COVID and PVS symptoms, there has been speculation
regarding the potential causal role of the persistent presence of spike protein driving  the chronic symptoms.

Additionally, a recent study has shown spike protein binding to fibrin resulting in inflammation ex vivo and neuropathy in animal experiments. S1 subunit is sufficient to cause formation of trypsin-resistant (hard to break down) fibrin clots when added to plasma from healthy individuals.

The persistent presence of S1 and the full-length spike protein across multiple long COVID cohorts lends further support to this hypothesis. Despite higher antigen persistence rates, the PVS participants with detectable
S1 had higher mean circulating S1 levels compared to the Long Covid participants. In our PVS-I  group, anti-S antibody levels were lower in those with circulating S1.

Why persistent spike antigen fails to elicit an antibody response, and what the source of persistent
spike in circulation is, requires further investigation.

Immunophenotyping of circulating PBMCs from participants with PVS revealed lower  levels of circulating CD4+ Tem, CXCR3 expressing CD4, as well as IL-4+/IL-6+ double positive CD4 T cell populations and higher TNFα secreting CD8 cell populations.

This is in contrast to our observations of higher levels of IL-4+/IL-6+ CD4 T cell populations in  the long COVID cohort. Elevated levels of anti-S IgG have been observed in Long COVID patients, possibly reflecting persistent S protein.

By contrast, within the PVS-I subgroup, the lower levels of anti-S antibodies were associated with a reduced number of vaccinations. Moreover, PVS participants in this study did not exhibit decreased circulating cortisol levels or increased fetuin (a blood protein secreted by the liver) levels, as reported for long COVID.

In addition, similar to what has been reported in long COVID, elevated antibody responses against EBV (Epstein-Barr virus) lytic antigen were detected among seropositive participants with PVS, suggesting recent reactivation of the virus.