Age-related immune response heterogeneity to SARS-CoV-2 vaccine BNT162b2

How aging impacts vaccine efficacy: known molecular and cellular mechanisms and future directions

Aging leads to a gradual dysregulation of immune functions, one consequence of which is reduced vaccine efficacy. In this review, we discuss several key contributing factors to the age-related decline in vaccine efficacy, such as alterations within the lymph nodes where germinal center (GC) reactions take place, alterations in the B cell compartment, alterations in the T cell compartment, and dysregulation of innate immune pathways. Additionally, we discuss several methods currently used in vaccine development to bolster vaccine efficacy in older adults. This review highlights the multifactorial defects that impair vaccine responses with aging.

Risk of SARS-CoV-2 reinfection: a systematic review and meta-analysis

This meta-analysis aims to synthesize global evidence on the risk of reinfection among people previously infected with SARS-CoV-2. We systematically searched PubMed, Scopus, Embase and Web of Science as of April 5, 2021. We conducted: (1) meta-analysis of cohort studies containing data sufficient for calculating the incidence rate of SARS-CoV-2 reinfection; (2) systematic review of case reports with confirmed SARS-CoV-2 reinfection cases. The reinfection incidence was pooled by zero-inflated beta distribution. The hazard ratio (HR) between reinfection incidence among previously infected individuals and new infection incidence among infection-naïve individuals was calculated using random-effects models. Of 906 records retrieved and reviewed, 11 studies and 11 case reports were included in the meta-analysis and the systematic review, respectively. The pooled SARS-CoV-2 reinfection incidence rate was 0.70 (standard deviation [SD] 0.33) per 10,000 person-days. The incidence of reinfection was lower than the incidence of new infection (HR = 0.12, 95% confidence interval 0.09-0.17). Our meta-analysis of studies conducted prior to the emergency of the more transmissible Omicron variant showed that people with a prior SARS-CoV-2 infection could be re-infected, and they have a lower risk of infection than those without prior infection. Continuing reviews are needed as the reinfection risk may change due to the rapid evolution of SARS-CoV-2 variants.

The Protection of Naturally Acquired Antibodies Against Subsequent SARS-CoV-2 Infection: A Systematic Review and Meta-Analysis

The specific antibodies induced by SARS-CoV-2 infection may provide protection against a subsequent infection. However, the efficacy and duration of protection provided by naturally acquired immunity against subsequent SARS-CoV-2 infection remain controversial. We systematically searched for the literature describing COVID-19 reinfection published before 07 February 2022. The outcomes were the pooled incidence rate ratio (IRR) for estimating the risk of subsequent infection. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the included studies. Statistical analyses were conducted using the R programming language 4.0.2. We identified 19 eligible studies including more than 3.5 million individuals without the history of COVID-19 vaccination. The efficacy of naturally acquired antibodies against reinfection was estimated at 84% (pooled IRR = 0.16, 95% CI: 0.14-0.18), with higher efficacy against symptomatic COVID-19 cases (pooled IRR = 0.09, 95% CI = 0.07-0.12) than asymptomatic infection (pooled IRR = 0.28, 95% CI = 0.14-0.54). In the subgroup analyses, the pooled IRRs of COVID-19 infection in health care workers (HCWs) and the general population were 0.22 (95% CI = 0.16-0.31) and 0.14 (95% CI = 0.12-0.17), respectively, with a significant difference (P = 0.02), and those in older (over 60 years) and younger (under 60 years) populations were 0.26 (95% CI = 0.15-0.48) and 0.16 (95% CI =  0.14-0.19), respectively. The risk of subsequent infection in the seropositive population appeared to increase slowly over time. In conclusion, naturally acquired antibodies against SARS-CoV-2 can significantly reduce the risk of subsequent infection, with a protection efficacy of 84%.Registration number: CRD42021286222.

Humoral and T-cell mediated response after administration of mRNA vaccine BNT162b2 in frail populations

Patients with frailty are considered to be at greater risk to get severe infection from SARS-CoV-2. One of the most effective strategies is vaccination. In our study we evaluated both the humoral immune response elicited by the vaccination at different time points, and the T-cell response in terms of interferon (IFN)-γ production in frail patients and healthy donors. Fifty-seven patients (31 patients undergoing hemodialysis and 26 HIV positive subjects) and 39 healthcare workers were enrolled. All participants received two doses of the mRNA vaccine BNT162b2. Healthcare workers showed a significantly higher antibody titer than patients twenty-one days after the first dose (p < 0.001). From the same time point we observed for both groups a decay of the antibody levels with a steeper slope of decline in the patients group. Regarding T-cell response the only significant difference between non-reactive and reactive subjects was found in median antibody levels, higher in the responders group than in non-responders. The healthcare workers seem to better respond to the vaccination in terms of antibodies production; the lack of T-cell response in about 50% of the participants seems to suggest that in our study population both humoral and cell-mediated response decline over time remarking the importance of the booster doses, particularly for frail patients.

Emerging cellular senescence-centric understanding of immunological aging and its potential modulation through dietary bioactive components

Immunological aging is strongly associated with the observable deleterious effects of human aging. Our understanding of the causes, effects, and therapeutics of aging immune cells has long been considered within the sole purview of immunosenescence. However, it is being progressively realized that immunosenescence may not be the only determinant of immunological aging. The cellular senescence-centric theory of aging proposes a more fundamental and specific role of immune cells in regulating senescent cell (SC) burden in aging tissues that has augmented the notion of senescence immunotherapy. Now, in addition, several emerging studies are suggesting that cellular senescence itself may be prevalent in aging immune cells, and that senescent immune cells exhibiting characteristic markers of cellular senescence, similar to non-leucocyte cells, could be among the key drivers of various facets of physiological aging. The present review integrates the current knowledge related to immunosenescence and cellular senescence in immune cells per se, and aims at providing a cohesive overview of these two phenomena and their significance in immunity and aging. We present evidence and rationalize that understanding the extent and impact of cellular senescence in immune cells vis-à-vis immunosenescence is necessary for truly comprehending the notion of an 'aged immune cell'. In addition, we also discuss the emerging significance of dietary factors such as phytochemicals, probiotic bacteria, fatty acids, and micronutrients as possible modulators of immunosenescence and cellular senescence. Evidence and opportunities related to nutritional bioactive components and immunological aging have been deliberated to augment potential nutrition-oriented immunotherapy during aging.

Waning effectiveness of SARS-CoV-2 mRNA vaccines in older adults: a rapid review

The U.S. Centers for Disease Control and Prevention (CDC) and other health agencies have recently recommended a booster dose of COVID-19 vaccines for specific vulnerable groups including adults 65 years and older. There is limited evidence whether vaccine effectiveness (VE) in older adults decreases over time, especially against severe COVID-19. We performed a rapid review of published studies available through 4 November 2021 that provide effectiveness data on messenger RNA (mRNA) vaccines approved/licensed in the United States and identified eight eligible studies which evaluated VE in older adults. There is evidence of a decline in VE against both severe acute respiratory syndrome coronavirus 2 infection and severe COVID-19 in older adults among studies which analyzed data up to July-October 2021. Our findings suggest that VE diminishes in older adults, which supports the current recommendation for a booster dose in this population.

Correlation between anti-S IgG and neutralizing antibody titers against three live SARS-CoV-2 variants in BNT162b2 vaccine recipients

We analyzed serially collected serum samples from healthy adults who underwent BNT162b2 vaccination to elucidate the association between spike (S)-IgG antibody titers determined by ELISA using the WHO international standard (NIBSC code 20/136) and neutralizing antibody titers against three live SARS-CoV-2 variants. This study included 53 health care workers who received two doses of the BNT162b2 vaccine. S-IgG and nucleocapsid (N)-IgG antibody titers were measured by ELISA. Neutralizing (NT) antibody responses against three variants (Wuhan D614 G: KUH003, Alpha, and Delta) were evaluated before and after the first and second vaccination. N-IgG were not detected in any serum samples. S-IgG antibody titers remarkably increased after two BNT162b2 vaccine doses in all participants. S-IgG antibody titers were strongly correlated with NT titers against three variants of live viruses: KUH003 (r = 0.86), Alpha (r = 0.72), and Delta (r = 0.84). Serum samples from participants after one dose of BNT162b2 neutralized Alpha efficiently (median titer, 113.0), but median NT titers against KUH003 and Delta variants were lower, 57.0 and 28.0, respectively (p < .01). Two doses of the BNT162b2 vaccine elicited a strong immune response in this study. The second dose was required for induction of a strong booster effect. Serum collected from BNT162b2 vaccine recipients contained significantly lower neutralizing activity against Delta than that of against KUH003 (p < .0001) and Alpha (p < .0001). If a new variant emerges, live virus-based NT titers should be examined in serum obtained from vaccine recipients to evaluate vaccine efficacy for protection against infection.

SARS-CoV-2 Specific Humoral Immune Responses after BNT162b2 Vaccination in Hospital Healthcare Workers

BACKGROUND

COVID-19 pandemic has led to a loss of human life in millions and devastating socio-economic consequences worldwide. So far, vaccination is the most effective long-term strategy to control and prevent severe COVID-19 disease. The aim of the current study was to evaluate the humoral immune responses raised against the BNT162b2 vaccine in hospital healthcare workers.

METHODS

Total number of 173 healthcare workers enrolled in the study. Their blood samples were collected in three different time intervals after the second SARS-CoV-2 vaccination and evaluated by the ELISA method to detect anti-spike protein IgM and IgG antibodies. The baseline characteristics of all participants were collected using questionnaires and were evaluated for finding any significant data.

RESULTS

Our results demonstrated that the levels of antibodies were higher in the young group (21-30 years old) and also among male participants. Moreover, the highest levels of antibodies were detected from the group that received the third shot vaccination.

CONCLUSIONS

Our results indicate that age, gender and third-dose vaccination can affect the levels of humoral immune responses against the BNT162b2 vaccine in healthcare workers.

A Simple Non-Invasive Score Based on Baseline Parameters Can Predict Outcome in Patients with COVID-19

We evaluated the role of CRP and other laboratory parameters in predicting the worsening of clinical conditions during hospitalization, ICU admission, and fatal outcome among patients with COVID-19. Consecutive adult inpatients with SARS-CoV-2 infection and respiratory symptoms treated in three different COVID centres were enrolled, and they were tested for laboratory parameters within 48 h from admission. Three-hundred ninety patients were enrolled. Age, baseline CRP, and LDH were associated with a P/F ratio < 200 during hospitalization. Male gender and CRP > 60 mg/L were shown to be independently associated with ICU admission. Lymphocytes < 1000 cell/μL were associated with the worst P/F ratio. CRP > 60 mg/L predicted exitus. We subsequently devised an 11-points numeric ordinary scoring system based on age, sex, CRP, and LDH at admission (ASCL score). Patients with an ASCL score of 0 or 2 were shown to be protected against a P/F ratio < 200, while patients with an ASCL score of 6 to 8 were shown to be at risk for P/F ratio < 200. Patients with an ASCL score ≥ 7 had a significantly increased probability of death during hospitalization. In conclusion, patients with elevated CRP and LDH and an ASCL score > 6 at admission should be prioritized for careful respiratory function monitoring and early treatment to prevent a progression of the disease.

Enhanced Vaccine Effectiveness during the Delta Phase of the COVID-19 Pandemic in the Medicare Population Supports a Multilayered Prevention Approach

Throughout the pandemic, individuals 65 years and older have contributed most COVID-19 related deaths. To best formulate effective vaccination and other prevention policies to protect older adults, large scale observational studies of these higher risk individuals are needed. We conducted a Vaccine Effectiveness (VE) study during the B.1.617.2 Delta variant phase of the pandemic in July and August 2021 in a cohort of 17 million Medicare beneficiaries of which 5.7 million were fully vaccinated. We found that individuals fully vaccinated with the Pfizer-BioNTech BNT162b2 and Moderna mRNA-1273 vaccines in January 2021 had 2.5 times higher breakthrough infections and hospitalizations than those fully vaccinated in March 2021, consistent with waning of vaccine-induced immunity. Measuring VE weekly, we found that VE against hospitalization, and even more so against infection, increased from July 2021 through August 2021, suggesting that in addition to the protective role of vaccination, increased masking or social distancing might have contributed to the unexpected increase in VE. Ongoing monitoring of Medicare beneficiaries should be a priority as new variants continue to emerge, and the VE of the new bivalent vaccines remains to be established. This could be accomplished with a large Medicare claims database and the analytics platform used for this study.

Antibody Response to COVID-19 mRNA Vaccine in Patients With Lung Cancer After Primary Immunization and Booster: Reactivity to the SARS-CoV-2 WT Virus and Omicron Variant

PURPOSE

To examine COVID-19 mRNA vaccine-induced binding and neutralizing antibody responses in patients with non-small-cell lung cancer (NSCLC) to SARS-CoV-2 614D (wild type [WT]) strain and variants of concern after the primary 2-dose and booster vaccination.

METHODS

Eighty-two patients with NSCLC and 53 healthy volunteers who received SARS-CoV-2 mRNA vaccines were included in the study. Blood was collected longitudinally, and SARS-CoV-2-specific binding and neutralizing antibody responses were evaluated by Meso Scale Discovery assay and live virus Focus Reduction Neutralization Assay, respectively.

RESULTS

A majority of patients with NSCLC generated binding and neutralizing antibody titers comparable with the healthy vaccinees after mRNA vaccination, but a subset of patients with NSCLC (25%) made poor responses, resulting in overall lower (six- to seven-fold) titers compared with the healthy cohort (P = < .0001). Although patients age > 70 years had lower immunoglobulin G titers (P = < .01), patients receiving programmed death-1 monotherapy, chemotherapy, or a combination of both did not have a significant impact on the antibody response. Neutralizing antibody titers to the B.1.617.2 (Delta), B.1.351 (Beta), and in particular, B.1.1.529 (Omicron) variants were significantly lower (P = < .0001) compared with the 614D (WT) strain. Booster vaccination led to a significant increase (P = .0001) in the binding and neutralizing antibody titers to the WT and Omicron variant. However, 2-4 months after the booster, we observed a five- to seven-fold decrease in neutralizing titers to WT and Omicron viruses.

CONCLUSION

A subset of patients with NSCLC responded poorly to the SARS-CoV-2 mRNA vaccination and had low neutralizing antibodies to the B.1.1.529 Omicron variant. Booster vaccination increased binding and neutralizing antibody titers to Omicron, but antibody titers declined after 3 months. These data highlight the concern for patients with cancer given the rapid spread of SARS-CoV-2 Omicron variant.

Prospective longitudinal analysis of antibody response after standard and booster doses of SARS-COV2 vaccination in patients with early breast cancer

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants brought waves of pandemics with breakthrough infections in vaccinated individuals. We analyzed the antibody responses after primary and booster vaccination in healthy controls (HC) and patients with early breast cancer (BC).

Methods

In this prospective longitudinal cohort study, the binding activity of serum antibody level against spike proteins and antigens of SARS-CoV-2 variants was measured within 21 days after each vaccination in the BC group and HC group.

Results

All participants, 40 in the BC and 20 in the HC group, had increased antibody response after vaccination. BC group, however, had weaker humoral responses than the HC group (IgG: 1.5, 2.3, 2.5-folds in BC vs. 1.9, 3.6, 4.0-folds in HC after each dose; IgA: 2.1, 3.0, 3.6-folds in BC vs. 4.2, 10.4, 5.2-folds in HC after each dose, respectively). Those under concurrent cytotoxic chemotherapy had weaker antibody response than the non-cytotoxic treatment group and HC. Adjunct use of steroids and age were not significant risk factors. The levels of binding antibody against the Delta and the Omicron (BA1) variants were lower than the wild-type, especially in BC.

Conclusion

In the waves of new sub-variants, our study suggests that an additional dose of vaccinations should be recommended according to the anti-cancer treatment modality in patients with BC who had received booster vaccination.

Correlation between Clinical and Immunological Variables and Humoral Response to SARS-CoV-2 Vaccination in Adult Patients with Antibody Deficiency Disorders

BACKGROUND

Prophylactic vaccination has proven to be the most effective strategy to fight the COVID-19 pandemic.

METHODS

This was a prospective observational cohort study involving 30 predominantly antibody deficiency disorders (ADD)-afflicted adult patients on immunoglobulin replacement therapy vaccinated with three doses of the mRNA-1273 COVID-19 vaccine, and 10 healthy controls. Anti-RBD IgG antibodies were determined in plasma samples collected just before the first dose of mRNA-based COVID-19 vaccine and on weeks 4, 8, 24, and 28 following the first vaccination. Patients were categorized based on the levels of anti-RBD antibodies determined on w8 as non-, low-, and responders. Chi-square and Kruskal-Wallis tests were used to see if any variables correlated with humoral response levels. Any adverse effects of the mRNA-based vaccine were also noted.

RESULTS

The COVID-19 vaccine was safe and well-tolerated. The humoral response elicited at w8 after vaccination depended on the type of ADD, the type of immunoglobulin deficiency, the presence of granulomatous lymphocytic interstitial lung disease, recent use of immunosuppressive drugs, and the switched memory B cells counts. The third vaccine dose boosted humoral response in previous responders to second dose but seldom in non-responders.

CONCLUSIONS

The humoral response of patients with predominant ADD depends mostly on the type of immunodeficiency and on the frequency of B and T cell populations.

SARS-CoV-2 vaccines: What we know, what we can do to improve them and what we could learn from other well-known viruses

In recent weeks, the rate of SARS-CoV-2 infections has been progressively increasing all over the globe, even in countries where vaccination programs have been strongly implemented. In these regions in 2021, a reduction in the number of hospitalizations and deaths compared to 2020 was observed. This decrease is certainly associated with the introduction of vaccination measures. The process of the development of effective vaccines represents an important challenge. Overall, the breakthrough infections occurring in vaccinated subjects are in most cases less severe than those observed in unvaccinated individuals. This review examines the factors affecting the immunogenicity of vaccines against SARS-CoV-2 and the possible role of nutrients in modulating the response of distinct immune cells to the vaccination.

Waning of specific antibodies against Delta and Omicron variants five months after a third dose of BNT162b2 SARS-CoV-2 vaccine in elderly individuals

The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination. The antibody response against Omicron was almost non-existent. Efficient boosting of antibody response against all variants, including Omicron, was observed following a third dose. The antibody response against the variants tested was significantly higher at one month following booster vaccination, compared with two months following primary vaccination, for all individuals, including the low antibody responders identified at two months following primary vaccination. The antibody response, for all variants tested, was significantly higher at four months post booster than at five months post primary vaccination, and the proportion of low responders remained low (6-11%). However, there was significant waning of antibody response in more than 95% of individuals at four months, compared to one month following booster. We also observed a robust memory B cell response following booster, which remained higher at four months post booster than prior to booster. However, the memory B cell responses were on the decline for 50% of individuals at four months following booster. Similarly, while the T cell response is sustained, at cohort level, at four months post booster, a substantial proportion of individuals (18.8 - 53.8%) exhibited T cell response at four months post booster that has waned to levels below their corresponding levels before booster. The findings show an efficient induction of immune response against SARS-CoV-2 variants following booster vaccination. However, the induced immunity by the third BNT162b2 vaccine dose was transient. The findings suggest that elderly individuals may require a fourth dose to provide protection against SARS-CoV-2.

Safety and immunogenicity of an AS03-adjuvanted plant-based SARS-CoV-2 vaccine in Adults with and without Comorbidities

The rapid spread of SARS-CoV-2 continues to impact humanity on a global scale with rising total morbidity and mortality. Despite the development of several effective vaccines, new products are needed to supply ongoing demand and to fight variants. We report herein a pre-specified interim analysis of the phase 2 portion of a Phase 2/3, randomized, placebo-controlled trial of a coronavirus virus-like particle (CoVLP) vaccine candidate, produced in plants that displays the SARS-CoV-2 spike glycoprotein, adjuvanted with AS03 (NCT04636697). A total of 753 participants were recruited between 25th November 2020 and 24th March 2021 into three groups: Healthy Adults (18-64 years: N = 306), Older Adults (≥65 years: N = 282) and Adults with Comorbidities (≥18 years: N = 165) and randomized 5:1 to receive two intramuscular doses of either vaccine (3.75 µg CoVLP/dose+AS03) or placebo, 21 days apart. This report presents safety, tolerability and immunogenicity data up to 6 months post-vaccination. The immune outcomes presented include neutralizing antibody (NAb) titres as measured by pseudovirion assay at days 21 and 42 as well as neutralizing antibody cross-reactivity to several variants of concern (VOCs): Alpha, Beta, Gamma, Delta, and Omicron (BA.1), up to 201 days post-immunization. Cellular (IFN-γ and IL-4 ELISpot) response data in day 21 and 42 peripheral blood are also presented. In this study, CoVLP+AS03 was well-tolerated and adverse events (AE) after each dose were generally mild to moderate and transient. Solicited AEs in Older Adults and Adults with Comorbidities were generally less frequent than in Healthy Adults and the reactogenicity was higher after the second dose. CoVLP+AS03 induced seroconversion in >35% of participants in each group after the first dose and in ~98% of participants, 21 days after the second dose. In all cohorts, 21-days after the second dose, NAb levels in sera against the vaccine strain were ~10-times those in a panel of convalescent sera. Cross-reactivity to Alpha, Beta and Delta variants was generally retained to day 201 (>80%) while cross-reactivity to the Gamma variant was reduced but still substantial at day 201 (73%). Cross-reactivity to the Omicron variant fell from 72% at day 42 to 20% at day 201. Almost all participants in all groups (>88%) had detectable cellular responses (IFN-γ, IL-4 or both) at 21 days after the second dose. A Th1-biased response was most evident after the first dose and was still present after the second dose. These data demonstrated that CoVLP+AS03 is well-tolerated and highly immunogenic, generating a durable (at least 6 months) immune response against different VOCs, in adults ≥18 years of age, with and without comorbidities.

Do we need to vaccinate every child against COVID-19: What evidence suggests-A systematic review of opinions

It is still debatable whether all children should receive the COVID-19 vaccine. The comparatively mild cases and low risk of COVID-19 in children compared to adults, as well as the lack of clarity on the relative effects of the disease and vaccine, indicate that the risk-benefit ratio of vaccination in children is more nuanced. To consider and highlight the complexity of policy decisions regarding COVID-19 vaccination in children, we outlined the points regarding for and against vaccination of children against COVID-19 in this systemic review. Using Medical Search Headings (MeSH) terms and keywords, we searched PubMed, PubMed Central, Scopus, and Google Scholar. The primary search term was COVID-19 vaccination (all synonyms), factors (all synonyms), and among children (all synonyms). A total of 367 articles were searched. Finally, 64 articles met the inclusion criteria and were included in the review. The major theme/tone of 28 (43.75%) articles was in favor of children's COVID vaccination, and they were highlighting the positive factors, whereas the major theme/tone of 20 (31.25%) articles was against it. Approximately 16 (25.0%) articles were in a neutral position. Major factors highlighted by articles in favor of childhood COVID vaccination were as follows: the increasing rate of disease burden (29 articles), prevention of interruption of academic activities of children or school reopening (24 articles), and a role in defense against COVID infection (21 articles). Major factors against childhood vaccination were as follows: mild infection among children (27 articles), ethical concerns and legal problems regarding the consent of minors (17 articles), and vaccine hesitancy among parents for childhood vaccination (11 articles). Whereas, factors of uncertainty were the role in the reduction of community transmission (19 articles), protection against MIS-C (10 articles), and defense against long COVID (7 articles). Considering all the factors of COVID-19 disease progression among children, a cautious approach will be essential before proceeding with COVID-19 vaccination in children.

Humoral immunity after second dose of BNT162b2 vaccine in Japanese communities: an observational cross-sectional study, Fukushima Vaccination Community Survey

To reveal waning humoral immunity after second dose BNT162b2 vaccinations in a rural Japanese community and determine factors affecting antibody titers. We aimed to report Immunoglobulin G (IgG) antibody against the SARS-CoV-2 spike (S1) protein levels and neutralizing activity in a large scale community based cohort.

METHODS

Participants in the observational cross-sectional study received a second dose of vaccination with BNT162b2 (Pfizer/BioNTech) and were not previously infected with COVID-19. Questionnaire-collected data on sex, age, adverse vaccine reactions, and medical history was obtained.

RESULTS

Data from 2496 participants revealed that older age groups reached a low antibody titer 90-120 days after the second vaccination. Neutralizing activity decreased with age; 35 (13.3%) of those aged ≥ 80 years had neutralizing activity under the cut-off value. Neutralizing activity > 179 days from the second vaccination was 11.6% compared to that at < 60 days from the second vaccination. Significantly lower IgG antibody titers and neutralizing activity were associated with age, male sex, increased time from second vaccination, smoking, steroids, immunosuppression, and comorbidities.

CONCLUSIONS

Antibody titer decreased substantially over time. Susceptible populations, older people, men, smokers, steroid users, immunosuppression users, and people with three or more comorbidities may require a special protection strategy.

Lipid nanoparticles (LNP) induce activation and maturation of antigen presenting cells in young and aged individuals

Despite the overwhelming success of mRNA-based vaccine in protecting against SARS-CoV-2 infection and reducing disease severity and hospitalization, little is known about the role lipid nanoparticles (LNP) play in initiating immune response. In this report we studied the adjuvantive impact of empty LNP with no mRNA cargo (eLNP) on anti-viral pathways and immune function of cells from young and aged individuals. We found that eLNP induced maturation of monocyte derived dendritic cells by measuring the expression of CD40, CD80, HLA-DR and production of cytokines including IFN-α,IL-6, IFN-γ, IL-12, and IL-21. Flow cytometry analysis of specific dendritic cell subsets showed that eLNP can induce CD40 expression and cytokine production in cDC1, cDC2 and monocytes. Empty LNP (eLNP) effects on dendritic cells and monocytes coincided with induction pIRF7 and pTBK1, which are both important in mitigating innate immune signaling. Interestingly our data show that in response to eLNP stimulus at 6 and 24 hrs, aged individuals have decreased CD40 expression and reduced IFN- γ output compared to young adults. Furthermore, we show that cDC1, cDC2, and CD14 ^dim CD16 ⁺ monocytes from healthy aged individuals have dysregulated anti-viral signaling response to eLNP stimulation as measured by the defect in type I IFN production, phosphorylation of IRF7, TBK-1, and immune function like phagocytosis. These data showed a novel function of eLNP in eliciting DC maturation and innate immune signaling pathways and that some of these functions are impaired in older individuals providing some suggestion of why older individuals (> 65 yrs of age) respond display lower immune responses and adverse events to SARS-CoV-2 mRNA-based vaccines.

COVID-19 breakthrough infections in vaccinated participants of the Safety and Efficacy of Preventative COVID Vaccines sub-study

BACKGROUND

The rate of breakthrough infection in vaccinated Ontarians during the Omicron wave is unknown.

METHODS

Active participants of the Safety and Efficacy of Preventative COVID Vaccines (STOPCoV) study (892 ≥age 70 years and 369 aged 30-50 years) were invited to participate in a sub-study evaluating breakthrough COVID-19 infection. Self-administered rapid antigen tests (RAT) were reported twice weekly and symptom questionnaires weekly for 6 weeks. The primary outcome was the proportion reporting a positive RAT.

RESULTS

A total of 806 e-consented, and 727 (90%) completed ≥1 RAT, with total 7,116 RATs completed between January 28 and March 29, 2022. Twenty out of twenty-five participants with a positive RAT had a booster vaccine prior to the positive test. All cases were mild, none requiring hospitalization. Nineteen had positive dried blood spot analysis for IgG antibody to the receptor binding domain (RBD) prior to the positive RAT. The mean normalized IgG ratio to RBD was 1.22 (SD 0.29) for younger and 0.98 (SD 0.44) for older participants, values similar to corresponding ratios for those without positive RATs and those in the main cohort. One hundred and five participants reported one and 96 reported ≥2 possible COVID-19 symptoms despite negative RATs. The false negative RAT was low (4% to 6.6 %) compared with subsequent positive nucleoprotein antibody.

CONCLUSIONS

Positive RAT for COVID-19 was infrequent (3.4%). We were unable to determine a protective antibody level against breakthrough infection. Our findings can inform public health COVID-19 restrictions guidelines. Our decentralized study provides a model for rapid institution of new questions during a pandemic.

Humoral response to COVID-19 vaccination in MS patients on disease modifying therapy: Immune profiles and clinical outcomes

BACKGROUND

Patients with multiple sclerosis (MS) on some disease modifying therapies (DMTs), particularly anti-CD20 and sphingosine-1-phosphate (S1P) modulators, are at increased risk of severe Coronavirus Disease 19 (COVID-19) and death. COVID-19 vaccinations are effective in preventing infection and severe disease, but humoral response to vaccination and outcomes of COVID-19 infection after vaccination in MS patients on DMTs remain less understood.

METHODS

In this retrospective single-center study, patients enrolled in the CLIMB (Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women's Hospital) study and biorepository who had been vaccinated against COVID-19 and had SARS-CoV-2 spike antibody (anti-SARS-CoV-2 S Roche-Elecsys) testing were identified and compared to healthy controls. Demographic data, serum immune profiles including lymphocyte count, B-cell count, and immunoglobulins, and clinical outcome of COVID-19 infection were collected.

RESULTS

254 patients (73.2% female, mean (SD) age 52.9 (11.2) years) were identified. When controlling for age, time since vaccination, and vaccine type, patients on fingolimod, ocrelizumab, rituximab, mycophenolate mofetil, natalizumab and teriflunomide had significantly lower levels of spike antibodies compared to healthy controls (n = 34). Longer duration of treatment was associated with lower spike antibody levels in patients on anti-CD20 therapy (p = 0.016) and S1P modulators (p = 0.016) compared to healthy controls. In patients on anti-CD20 therapy, higher spike antibody levels were associated with higher CD20 cell count (p<0.001), and longer time since last anti-CD20 therapy infusion (p<0.001). 92.8% (13/14) vaccine responders (spike antibody titer >100 ug/dL) on anti-CD20 therapy demonstrated B-cell reconstitution (mean CD20 3.6%). Only 1 out of 86 patients with CD20 of 0% had a measurable spike antibody response to vaccination. During follow-up (mean 270 days), five patients were diagnosed with COVID-19 after vaccination (incidence 1.9%), all of whom had spike antibody < 20 ug/dL. No patients required ICU care or died.

CONCLUSIONS

Patients on some DMTs demonstrate reduced humoral immunity after Sars-CoV-2 vaccination. Longer duration of anti-CD20 therapy and reduced CD20 cell count is associated with blunted humoral response to vaccination. CD20 reconstitution >0.1% appears necessary, but not always sufficient, for humoral response to vaccination. Breakthrough COVID-19 infection in our cohort of MS patients on DMT was higher than in population studies. We propose that adjustment of B-cell therapy administration to allow for B-cell reconstitution prior to vaccination should be considered.

Differential avidity determination of IgG directed towards the receptor-binding domain (RBD) of SARS-CoV-2 wild-type and its variants in one assay: Rational tool for the assessment of protective immunity

The avidity (binding strength) of IgG directed towards the receptor-binding domain (RBD) of spike protein has been recognized as a central marker in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology. It seems to be linked to increased infection-neutralization potential and therefore might indicate protective immunity. Using a prototype line assay based on the established recomLine SARS-CoV-2 assay, supplemented with RBD of the delta and the omicron variant, differential avidity determination of IgG directed towards RBD of wild-type (WT) SARS-CoV-2 and distinct variants was possible within one assay. Our data confirm that natural SARS-CoV-2 infection or one vaccination step lead to low avidity IgG, whereas further vaccination steps gradually increase avidity to high values. High avidity is not reached by infection alone. After infection with WT SARS-CoV-2 or vaccination based on mRNA WT, the avidity of cross-reacting IgG directed towards RBD of the delta variant only showed marginal differences compared to IgG directed towards RBD WT. In contrast, the avidity of IgG cross-reacting with RBD of the omicron variant was always much lower than for IgG RBD WT, except after the third vaccination step. Therefore, parallel avidity testing of RBD WT and omicron seems to be mandatory for a significant assessment of protective immunity towards SARS-CoV-2.

Absence of antibody responses to SARS-CoV-2 N protein in COVID-19 vaccine breakthrough cases

Understanding the risk factors for breakthrough coronavirus disease 2019 (COVID-19) (BC19) is critical to inform policy. Herein, we assessed Delta (Lineage B.1.617.2) variant-specific effectiveness of the BNT162b2 (Pfizer) vaccine and characterized Delta-driven BC19 cases (fully vaccinated individuals who get infected) with known-time-since-vaccination. In this longitudinal prospective study (January 21-October 30, 2021), 90 naïve and 15 convalescent individuals were enrolled at the initiation of vaccination. Samples from 27 unvaccinated individuals with previous laboratory-confirmed COVID-19 diagnosis were collected at a single time point. Longitudinal serology profile (antibodies against severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] S and N proteins) and live-virus-based neutralization capacities were assessed while controlling for age. Sex, age, history of reactions to the COVID-19 vaccine, and viral neutralization capacities were identified as significant risk factors for breakthrough COVID-19. At 8 months postvaccination, male sex, individuals ⩾65 years of age, and individuals who experienced noticeable side effects with the COVID-19 vaccine were at 5.47 (p-value = 0.0102), 4.33 (p-value = 0.0236), and 4.95 (p-value = 0.0159) fold greater risk of BC19 as compared to their peers, respectively. Importantly, every five-fold increase in viral neutralization capacities (by live-virus-based assays) was significantly associated with ~4-fold reduction in the risk occurrence of breakthrough COVID-19 (p-value = 0.045). Vaccine boosting remarkably increased these viral neutralization capacities by 16.22-fold (p- value = 0.0005), supporting the importance of the BNT162b2 booster in efforts to control the incursion of future variants into the population at large. Strikingly, BC19 cases exhibited a delayed/absent antibody response to the N protein, suggesting limited exposure to the virus. Since antibodies against N protein are widely used to evaluate the extent of virus spread in communities, our finding has important implications on the utility of existing serological diagnostic and surveillance for COVID-19.

Vaccine effectiveness against SARS-CoV-2 reinfection during periods of Alpha, Delta, or Omicron dominance: A Danish nationwide study

BACKGROUND

Individuals with a prior Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection have a moderate to high degree of protection against reinfection, though seemingly less so when the Omicron variant of SARS-CoV-2 started to circulate. The aim of this study was to evaluate the vaccine effectiveness (VE) against SARS-CoV-2 reinfection, Coronavirus Disease 2019 (COVID-19)-related hospitalization, and COVID-19-related death, in individuals with prior SARS-CoV-2 infection, and to assess the effect of time since vaccination during periods with different dominant SARS-CoV-2 variants.

METHODS AND FINDINGS

This study used a nationwide cohort design including all individuals with a confirmed SARS-CoV-2 infection, who were alive, and residing in Denmark between 1 January 2020 and 31 January 2022. Using Danish nationwide registries, we obtained information on SARS-CoV-2 infections, COVID-19 vaccination, age, sex, comorbidity, staying at hospital, and country of origin. The study population included were individuals with prior SARS-CoV-2 infection. Estimates of VE against SARS-CoV-2 reinfection with 95% confidence intervals (CIs) were calculated using a Poisson regression model and adjusted for age, sex, country of origin, comorbidity, staying at hospital, calendar time, and test incidence using a Cox regression model. The VE estimates were calculated separately for three periods with different dominant SARS-CoV-2 variants (Alpha (B.1.1.7), Delta (B.1.617.2), or Omicron (B.1.1.529)) and by time since vaccination using unvaccinated as the reference. In total, 148,527 person-years and 44,192 SARS-CoV-2 infections were included for the analysis regarding reinfections. The study population comprised of 209,814 individuals infected before or during the Alpha period, 292,978 before or during the Delta period, and 245,530 before or during the Omicron period. Of these, 40,281 individuals had completed their primary vaccination series during the Alpha period (19.2%), 190,026 during the Delta period (64.9%), and 158,563 during the Omicron period (64.6%). VE against reinfection following any COVID-19 vaccine type administered in Denmark, peaked at 71% (95% CI: -Inf to 100%) at 104 days or more after vaccination during the Alpha period, 94% (95% CI: 92% to 96%) 14 to 43 days after vaccination during the Delta period, and 60% (95% CI: 58% to 62%) 14 to 43 days after vaccination during the Omicron period. Waning immunity following vaccination was observed and was most pronounced during the Omicron period. Due to too few events, it was not possible to estimate VE for hospitalization and death. Study limitations include potentially undetected reinfections, differences in health-seeking behavior, or risk behavior between the compared groups.

CONCLUSIONS

This study shows that in previously infected individuals, completing a primary vaccination series was associated with a significant protection against SARS-CoV-2 reinfection compared with no vaccination. Even though vaccination seems to protect to a lesser degree against reinfection with the Omicron variant, these findings are of public health relevance as they show that previously infected individuals still benefit from COVID-19 vaccination in all three variant periods.

Broad Antiviral Effects of Echinacea purpurea against SARS-CoV-2 Variants of Concern and Potential Mechanism of Action

SARS-CoV-2 variants of concern (VOCs) represent an alarming threat as they show altered biological behavior and may escape vaccination effectiveness. Broad-spectrum antivirals could play an important role to control infections. The activity of Echinacea purpurea (Echinaforce® extract, EF) against (i) VOCs B1.1.7 (alpha), B.1.351.1 (beta), P.1 (gamma), B1.617.2 (delta), AV.1 (Scottish), B1.525 (eta), and B.1.1.529.BA1 (omicron); (ii) SARS-CoV-2 spike (S) protein-pseudotyped viral particles and reference strain OC43 as well as (iii) wild type SARS-CoV-2 (Hu-1) was analyzed. Molecular dynamics (MD) were applied to study the interaction of Echinacea's phytochemical markers with known pharmacological viral and host cell targets. EF extract broadly inhibited the propagation of all investigated SARS-CoV-2 VOCs as well as the entry of SARS-CoV-2 pseudoparticles at EC50's ranging from 3.62 to 12.03 µg/mL. The preventive addition of 25 µg/mL EF to epithelial cells significantly reduced sequential infection with SARS-CoV-2 (Hu-1) and OC43. MD analyses showed constant binding affinities to VOC-typical S protein variants for alkylamides, caftaric acid, and feruloyl-tartaric acid in EF extract and interactions with serine protease TMPRSS-2. EF extract demonstrated stable virucidal activity across seven tested VOCs, likely due to the constant affinity of the contained phytochemical substances to all spike variants. A possible interaction of EF with TMPRSS-2 partially would explain the cell protective benefits of the extract by the inhibition of membrane fusion and cell entry. EF may therefore offer a supportive addition to vaccination endeavors in the control of existing and future SARS-CoV-2 virus mutations.

Longitudinal Analyses after COVID-19 Recovery or Prolonged Infection Reveal Unique Immunological Signatures after Repeated Vaccinations

To develop preventive and therapeutic measures against coronavirus disease 2019, the complete characterization of immune response and sustained immune activation following viral infection and vaccination are critical. However, the mechanisms controlling intrapersonal variation in antibody titers against SARS-CoV-2 antigens remain unclear. To gain further insights, we performed a robust molecular and cellular investigation of immune responses in infected, recovered, and vaccinated individuals. We evaluated the serum levels of 29 cytokines and their correlation with neutralizing antibody titer. We investigated memory B-cell response in patients infected with the original SARS-CoV-2 strain or other variants, and in vaccinated individuals. Longitudinal correlation analyses revealed that post-vaccination neutralizing potential was more strongly associated with various serum cytokine levels in recovered patients than in naïve individuals. We found that IL-10, CCL2, CXCL10, and IL-12p40 are candidate biomarkers of serum-neutralizing antibody titer after the vaccination of recovered individuals. We found a similar distribution of virus-specific antibody gene families in triple-vaccinated individuals and a patient with COVID-19 pneumonia for 1 year. Thus, distinct immune responses occur depending on the viral strain and clinical history, suggesting that therapeutic options should be selected on a case-by-case basis. Candidate biomarkers that correlate with repeated vaccination may support the efficacy and safety evaluation systems of mRNA vaccines and lead to the development of novel vaccine strategies.

Fully understanding the efficacy profile of the COVID-19 vaccination and its associated factors in multiple real-world settings

We performed a review study according to recent COVID-19 vaccines' real-world data to provide comparisons between COVID-19 vaccines regarding their relative efficacy. Although most vaccine platforms showed comparable effectiveness and efficacy, we highlight critical points and recent developments generated in studies that might affect vaccine efficacy including population-dependent effects of the vaccine (transplantation, adiposity, and specific comorbidities, as well as older age, male sex, ethnicity, and prior infection), vaccine type, variants of concern (VOC), and an extended vaccine schedule. Owing to these factors, community-based trials can be of great importance in determining vaccine effectiveness in a systematic manner; thus, uncertainty remains regarding vaccine efficacy. Long immune protection of vaccination with BNT162b2 or ChAdOx1 nCoV-19 has been demonstrated to be up to 61 months and 5-12 months after the previous infection, and boosting infection-acquired immunity for both the first and second doses of the BNT162b2 and ChAdOx1 nCoV-19 vaccines was correlated with high and durable protection. However, large cohort and longitudinal studies are required for the evaluation of immunity dynamics and longevity in unvaccinated, vaccinated, and infected individuals, as well as vaccinated convalescent individuals in real-world settings. Regarding the likelihood of vaccine escape variants evolving, an ongoing examination of the protection conferred against an evolving virus (new variant) by an extended schedule can be crucial.

BNT162b2-induced neutralizing and non-neutralizing antibody functions against SARS-CoV-2 diminish with age

Each severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant renews concerns about decreased vaccine neutralization weakening efficacy. However, while prevention of infection varies, protection from disease remains and implicates immunity beyond neutralization in vaccine efficacy. Polyclonal antibodies function through Fab domains that neutralize virus and Fc domains that induce non-neutralizing responses via engagement of Fc receptors on immune cells. To understand how vaccines promote protection, we leverage sera from 51 SARS-CoV-2 uninfected individuals after two doses of the BNT162b2 mRNA vaccine. We show that neutralizing activities against clinical isolates of wild-type and five SARS-CoV-2 variants, including Omicron BA.2, link to FcγRIIIa/CD16 non-neutralizing effector functions. This is associated with post-translational afucosylation and sialylation of vaccine-specific antibodies. Further, polyfunctional neutralizing and non-neutralizing breadth, magnitude, and coordination diminish with age. Thus, studying Fc functions in addition to Fab-mediated neutralization provides greater insight into vaccine efficacy for vulnerable populations, such as the elderly, against SARS-CoV-2 and novel variants.

Evidence of premature lymphocyte aging in people with low anti-spike antibody levels after BNT162b2 vaccination

SARS-CoV-2 vaccines have unquestionably blunted the overall impact of the COVID-19 pandemic, but host factors such as age, sex, obesity, and other co-morbidities can affect vaccine efficacy. We identified individuals in a relatively healthy population of healthcare workers (CORALE study cohort) who had unexpectedly low peak anti-spike receptor binding domain (S-RBD) antibody levels after receiving the BNT162b2 vaccine. Compared to matched controls, "low responders" had fewer spike-specific antibody-producing B cells after the second and third/booster doses. Moreover, their spike-specific T cell receptor (TCR) repertoire had less depth and their CD4+ and CD8+T cell responses to spike peptide stimulation were less robust. Single cell transcriptomic evaluation of peripheral blood mononuclear cells revealed activation of aging pathways in low responder B and CD4+T cells that could underlie their attenuated anti-S-RBD antibody production. Premature lymphocyte aging may therefore contribute to a less effective humoral response and could reduce vaccination efficacy.

Antibody and T-Cell Subsets Analysis Unveils an Immune Profile Heterogeneity Mediating Long-term Responses in Individuals Vaccinated Against SARS-CoV-2

BACKGROUND

Based on the fact that coronavirus disease 2019 (COVID-19) is still spreading despite worldwide vaccine administration, there is an imperative need to understand the underlying mechanisms of vaccine-induced interindividual immune response variations.

METHODS

We compared humoral and cellular immune responses in 127 individuals vaccinated with either BNT162b2, mRNA-1273, or ChAdOx1-nCoV-19 vaccine.

RESULTS

Both mRNA vaccines induced faster and stronger humoral responses as assessed by high spike- and RBD-specific antibody titers and neutralizing efficacy in comparison to ChAdOx1-nCoV-19 vaccine. At 7 months postvaccination, a decreasing trend in humoral responses was observed, irrespective of the vaccine administered. Correlation analysis between anti-S1 IgG and interferon- (IFN-) production unveiled a heterogeneous immune profile among BNT162b2-vaccinated individuals. Specifically, vaccination in the high-responder group induced sizable populations of polyfunctional memory CD4 helper T cells (TH1), follicular helper T cells (TFH), and T cells with features of stemness (TSCM), along with high neutralizing antibody production that persisted up to 7 months. In contrast, low responders were characterized by significantly lower antibody titers and memory T cells and a considerably lower capacity for interleukin-2 and IFN- production.

CONCLUSIONS

We identified that long-term humoral responses correlate with the individuals ability to produce antigen-specific persistent memory T-cell populations.

SARS-COV-2 antibody responses to AZD1222 vaccination in West Africa

Real-world data on vaccine-elicited neutralising antibody responses for two-dose AZD1222 in African populations are limited. We assessed baseline SARS-CoV-2 seroprevalence and levels of protective neutralizing antibodies prior to vaccination rollout using binding antibodies analysis coupled with pseudotyped virus neutralisation assays in two cohorts from West Africa: Nigerian healthcare workers (n = 140) and a Ghanaian community cohort (n = 527) pre and post vaccination. We found 44 and 28% of pre-vaccination participants showed IgG anti-N positivity, increasing to 59 and 39% respectively with anti-receptor binding domain (RBD) IgG-specific antibodies. Previous IgG anti-N positivity significantly increased post two-dose neutralizing antibody titres in both populations. Serological evidence of breakthrough infection was observed in 8/49 (16%). Neutralising antibodies were observed to wane in both populations, especially in anti-N negative participants with an observed waning rate of 20% highlighting the need for a combination of additional markers to characterise previous infection. We conclude that AZD1222 is immunogenic in two independent West African cohorts with high background seroprevalence and incidence of breakthrough infection in 2021. Waning titres post second dose indicates the need for booster dosing after AZD1222 in the African setting despite hybrid immunity from previous infection.

COVID-19 vaccine update: vaccine effectiveness, SARS-CoV-2 variants, boosters, adverse effects, and immune correlates of protection

Coronavirus Disease 2019 (COVID-19) has been the most severe public health challenge in this century. Two years after its emergence, the rapid development and deployment of effective COVID-19 vaccines have successfully controlled this pandemic and greatly reduced the risk of severe illness and death associated with COVID-19. However, due to its ability to rapidly evolve, the SARS-CoV-2 virus may never be eradicated, and there are many important new topics to work on if we need to live with this virus for a long time. To this end, we hope to provide essential knowledge for researchers who work on the improvement of future COVID-19 vaccines. In this review, we provided an up-to-date summary for current COVID-19 vaccines, discussed the biological basis and clinical impact of SARS-CoV-2 variants and subvariants, and analyzed the effectiveness of various vaccine booster regimens against different SARS-CoV-2 strains. Additionally, we reviewed potential mechanisms of vaccine-induced severe adverse events, summarized current studies regarding immune correlates of protection, and finally, discussed the development of next-generation vaccines.

Limited cross-variant immune response from SARS-CoV-2 Omicron BA.2 in naïve but not previously infected outpatients

Omicron is currently the dominant SARS-CoV-2 variant and several sublineages have emerged. Questions remain about the impact of previous SARS-CoV-2 exposure on cross-variant immune responses elicited by the SARS-CoV-2 Omicron sublineage BA.2 compared to BA.1. Here we show that without previous history of COVID-19, BA.2 infection induces a reduced immune response against all variants of concern (VOC) compared to BA.1 infection. The absence of ACE2 binding in sera of previously naïve BA.1 and BA.2 patients indicates a lack of meaningful neutralization. In contrast, anti-spike antibody levels and neutralizing activity greatly increased in the BA.1 and BA.2 patients with a previous history of COVID-19. Transcriptome analyses of peripheral immune cells showed significant differences in immune response and specific antibody generation between BA.1 and BA.2 patients as well as significant differences in expression of specific immune genes. In summary, prior infection status significantly impacts the innate and adaptive immune response against VOC following BA.2 infection.

Parallel detection of SARS-CoV-2 epitopes reveals dynamic immunodominance profiles of CD8+ T memory cells in convalescent COVID-19 donors

Objectives

High-magnitude CD8⁺ T cell responses are associated with mild COVID-19 disease; however, the underlying characteristics that define CD8⁺ T cell-mediated protection are not well understood. The antigenic breadth and the immunodominance hierarchies of epitope-specific CD8⁺ T cells remain largely unexplored and are essential for the development of next-generation broad-protective vaccines. This study identified a broad spectrum of conserved SARS-CoV-2 CD8⁺ T cell epitopes and defined their respective immunodominance and phenotypic profiles following SARS-CoV-2 infection.

Methods

CD8⁺ T cells from 51 convalescent COVID-19 donors were analysed for their ability to recognise 133 predicted and previously described SARS-CoV-2-derived peptides restricted by 11 common HLA class I allotypes using heterotetramer combinatorial coding, which combined with phenotypic markers allowed in-depth ex vivo profiling of CD8⁺ T cell responses at quantitative and phenotypic levels.

Results

A comprehensive panel of 49 mostly conserved SARS-CoV-2-specific CD8⁺ T cell epitopes, including five newly identified low-magnitude epitopes, was established. We confirmed the immunodominance of HLA-A*01:01/ORF1ab_1637-1646 and B*07:02/N_105-113 and identified B*35:01/N_325-333 as a third epitope with immunodominant features. The magnitude of subdominant epitope responses, including A*03:01/N_361-369 and A*02:01/S_269-277, depended on the donors' HLA-I context. All epitopes expressed prevalent memory phenotypes, with the highest memory frequencies in severe COVID-19 donors.

Conclusion

SARS-CoV-2 infection induces a predominant CD8⁺ T memory response directed against a broad spectrum of conserved SARS-CoV-2 epitopes, which likely contributes to long-term protection against severe disease. The observed immunodominance hierarchy emphasises the importance of T cell epitopes derived from nonspike proteins to the overall protective and cross-reactive immune response, which could aid future vaccine strategies.

Antibody response to a third booster dose of SARS-CoV-2 vaccination in adults with haematological and solid cancer: a systematic review

BACKGROUND

Patients living with cancer are at a significantly increased risk of morbidity and mortality after infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This systematic review aims to investigate the current available evidence about the immunogenicity of SARS-CoV-2 booster vaccines in patients living with cancer.

METHODS

A systematic search was undertaken for studies published until March 1, 2022. A systematic narrative review was undertaken to include all studies that evaluated the efficacy of booster vaccines against SARS-CoV-2 in patients with cancer.

RESULTS

Fifteen studies encompassing 1205 patients with cancer were included. We found that a booster vaccine dose induced a higher response in patients with solid cancer as compared to haematological malignancies. Recent systemic anticancer therapy does not appear to affect seroconversion in solid organ malignancies, however, there is an association between B-cell depleting therapies and poor seroconversion in haematological patients.

CONCLUSIONS

Third booster vaccination induces an improved antibody response to SARS-CoV-2 in adults with haematological and solid cancer, relative to patients who only receive two doses. Access to vaccination boosters should be made available to patients at risk of poor immunological responses, and the provision of fourth doses may be of benefit to this vulnerable population.

REGISTRATION

PROSPERO number CRD42021270420.

A multinational, phase 2, randomised, adaptive protocol to evaluate immunogenicity and reactogenicity of different COVID-19 vaccines in adults ≥75 already vaccinated against SARS-CoV-2 (EU-COVAT-1-AGED): a trial conducted within the VACCELERATE network

Background

In the ongoing COVID-19 pandemic, advanced age is a risk factor for a severe clinical course of SARS-CoV-2 infection. Thus, older people may benefit in particular from booster doses with potent vaccines and research should focus on optimal vaccination schedules. In addition to each individual’s medical history, immunosenescence warrants further research in this population. This study investigates vaccine-induced immune response over 1 year.

Methods/design

EU-COVAT-1-AGED is a randomised controlled, adaptive, multicentre phase II protocol evaluating different booster strategies in individuals aged ≥75 years (n=600) already vaccinated against SARS-CoV-2. The initial protocol foresaw a 3rd vaccination (1st booster) as study intervention. The present modified Part B of this trial foresees testing of mRNA-1273 (Spikevax®) vs. BNT162b2 (Comirnaty®) as 4th vaccination dose (2nd booster) for comparative assessment of their immunogenicity and safety against SARS-CoV-2 wild-type and variants. The primary endpoint of the trial is to assess the rate of 2-fold antibody titre increase 14 days after vaccination measured by quantitative enzyme-linked immunosorbent assay (Anti-RBD-ELISA) against wild-type virus. Secondary endpoints include the changes in neutralising antibody titres (Virus Neutralisation Assay) against wild-type as well as against Variants of Concern (VOC) at 14 days and up to 12 months. T cell response measured by qPCR will be performed in subgroups at 14 days as exploratory endpoint. Biobanking samples are being collected for neutralising antibody titres against potential future VOC. Furthermore, potential correlates between humoral immune response, T cell response and neutralising capacity will be assessed.

The primary endpoint analysis will be triggered as soon as for all patients the primary endpoint (14 days after the 4th vaccination dose) has been observed.

Discussion

The EU-COVAT-1-AGED trial Part B compares immunogenicity and safety of mRNA-1273 (Spikevax®) and BNT162b2 (Comirnaty®) as 4th SARS-CoV-2 vaccine dose in adults ≥75 years of age. The findings of this trial have the potential to optimise the COVID-19 vaccination strategy for this at-risk population.

Trial registration

ClinicalTrials.govNCT05160766. Registered on 16 December 2021.

Protocol version: V06_0: 27 July 2022

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06791-y.

Signs of immunosenescence correlate with poor outcome of mRNA COVID-19 vaccination in older adults

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is effective in preventing COVID-19 hospitalization and fatal outcome. However, several studies indicated that there is reduced vaccine effectiveness among older individuals, which is correlated with their general health status^1,2. How and to what extent age-related immunological defects are responsible for the suboptimal vaccine responses observed in older individuals receiving SARS-CoV-2 messenger RNA vaccine, is unclear and not fully investigated^1,3-5. In this observational study, we investigated adaptive immune responses in adults of various ages (22-99 years old) receiving 2 doses of the BNT162b2 mRNA vaccine. Vaccine-induced Spike-specific antibody, and T and memory B cell responses decreased with increasing age. These responses positively correlated with the percentages of peripheral naïve CD4⁺ and CD8⁺ T cells and negatively with CD8⁺ T cells expressing signs of immunosenescence. Older adults displayed a preferred T cell response to the S2 region of the Spike protein, which is relatively conserved and a target for cross-reactive T cells induced by human 'common cold' coronaviruses. Memory T cell responses to influenza virus were not affected by age-related changes, nor the SARS-CoV-2-specific response induced by infection. Collectively, we identified signs of immunosenescence correlating with the outcome of vaccination against a new viral antigen to which older adults are immunologically naïve. This knowledge is important for the management of COVID-19 infections in older adults.

Immunogenicity and reactogenicity of SARS-CoV-2 vaccines in people living with HIV in the Netherlands: A nationwide prospective cohort study

BACKGROUND

Vaccines can be less immunogenic in people living with HIV (PLWH), but for SARS-CoV-2 vaccinations this is unknown. In this study we set out to investigate, for the vaccines currently approved in the Netherlands, the immunogenicity and reactogenicity of SARS-CoV-2 vaccinations in PLWH.

METHODS AND FINDINGS

We conducted a prospective cohort study to examine the immunogenicity of BNT162b2, mRNA-1273, ChAdOx1-S, and Ad26.COV2.S vaccines in adult PLWH without prior COVID-19, and compared to HIV-negative controls. The primary endpoint was the anti-spike SARS-CoV-2 IgG response after mRNA vaccination. Secondary endpoints included the serological response after vector vaccination, anti-SARS-CoV-2 T-cell response, and reactogenicity. Between 14 February and 7 September 2021, 1,154 PLWH (median age 53 [IQR 44-60] years, 85.5% male) and 440 controls (median age 43 [IQR 33-53] years, 28.6% male) were included in the final analysis. Of the PLWH, 884 received BNT162b2, 100 received mRNA-1273, 150 received ChAdOx1-S, and 20 received Ad26.COV2.S. In the group of PLWH, 99% were on antiretroviral therapy, 97.7% were virally suppressed, and the median CD4+ T-cell count was 710 cells/μL (IQR 520-913). Of the controls, 247 received mRNA-1273, 94 received BNT162b2, 26 received ChAdOx1-S, and 73 received Ad26.COV2.S. After mRNA vaccination, geometric mean antibody concentration was 1,418 BAU/mL in PLWH (95% CI 1322-1523), and after adjustment for age, sex, and vaccine type, HIV status remained associated with a decreased response (0.607, 95% CI 0.508-0.725, p < 0.001). All controls receiving an mRNA vaccine had an adequate response, defined as >300 BAU/mL, whilst in PLWH this response rate was 93.6%. In PLWH vaccinated with mRNA-based vaccines, higher antibody responses were predicted by CD4+ T-cell count 250-500 cells/μL (2.845, 95% CI 1.876-4.314, p < 0.001) or >500 cells/μL (2.936, 95% CI 1.961-4.394, p < 0.001), whilst a viral load > 50 copies/mL was associated with a reduced response (0.454, 95% CI 0.286-0.720, p = 0.001). Increased IFN-γ, CD4+ T-cell, and CD8+ T-cell responses were observed after stimulation with SARS-CoV-2 spike peptides in ELISpot and activation-induced marker assays, comparable to controls. Reactogenicity was generally mild, without vaccine-related serious adverse events. Due to the control of vaccine provision by the Dutch National Institute for Public Health and the Environment, there were some differences between vaccine groups in the age, sex, and CD4+ T-cell counts of recipients.

CONCLUSIONS

After vaccination with BNT162b2 or mRNA-1273, anti-spike SARS-CoV-2 antibody levels were reduced in PLWH compared to HIV-negative controls. To reach and maintain the same serological responses as HIV-negative controls, additional vaccinations are probably required.

TRIAL REGISTRATION

The trial was registered in the Netherlands Trial Register (NL9214). https://www.trialregister.nl/trial/9214.

The bullwhip effect, T-cell telomeres, and SARS-CoV-2

Both myeloid cells, which contribute to innate immunity, and lymphoid cells, which dominate adaptive immunity, partake in defending against SARS-CoV-2. In response to the virus, the otherwise slow haematopoietic production supply chain quickly unleashes its preconfigured myeloid element, which largely resists a bullwhip-like effect. By contrast, the lymphoid element risks a bullwhip-like effect when it produces T cells and B cells that are specifically designed to clear the virus. As T-cell production is telomere-length dependent and telomeres shorten with age, older adults are at higher risk of a T-cell shortfall when contracting SARS-CoV-2 than are younger adults. A poorly calibrated adaptive immune response, stemming from a bullwhip-like effect, compounded by a T-cell deficit, might thus contribute to the propensity of people with inherently short T-cell telomeres to develop severe COVID-19. The immune systems of these individuals might also generate an inadequate T-cell response to anti-SARS-CoV-2 vaccination.

Geriatric Health Care During the COVID-19 Pandemic: Managing the Health Crisis

COVID-19 pandemic significantly threatens the health and well-being of older adults. Aging-related changes, including multimorbidity, weakened immunity and frailty, may make older people more susceptible to severe infection and place them at higher risk of morbidity and mortality from COVID-19. Various quarantine measures have been implemented to control the spread of COVID-19. Nevertheless, such social distancing has disrupted routine health care practices, such as accessibility of medical services and long-term continuous care services. The medical management of older adults with multimorbidity is significantly afflicted by COVID-19. Older persons with frailty or multiple chronic disease may poorly adapt to the altered health care system, having detrimental consequences on their physical and mental health. COVID-19 pandemic has posed great challenges to the health of older adults. We highlighted the difficulties and obstacles of older adults during this unprecedented time. Also, we provided potential strategies and recommendations for actions to mitigate the COVID-19 pandemic threats. Certain strategies like community primary health care, medication delivery and home care support are adopted by many health facilities and caregivers, whereas other services such as internet hospital and virtual medical care are promoted to be accessible in many regions. However, guidelines and policies based on high-quality data are still needed for better health promotion of older groups with increasing resilience during the COVID-19 pandemic.

Humoral response and neutralising capacity at 6 months post-vaccination against COVID-19 among institutionalised older adults in Argentina

The COVID-19 pandemic has particularly affected older adults residing in nursing homes, resulting in high rates of hospitalisation and death. Here, we evaluated the longitudinal humoral response and neutralising capacity in plasma samples of volunteers vaccinated with different platforms (Sputnik V, BBIBP-CorV, and AZD1222). A cohort of 851 participants, mean age 83 (60-103 years), from the province of Buenos Aires, Argentina were included. Sequential plasma samples were taken at different time points after vaccination. After completing the vaccination schedule, infection-naïve volunteers who received either Sputnik V or AZD1222 exhibited significantly higher specific anti-Spike IgG titers than those who received BBIBP-CorV. Strong correlation between anti-Spike IgG titers and neutralising activity levels was evidenced at all times studied (rho=0.7 a 0.9). Previous exposure to SARS-CoV-2 and age <80 years were both associated with higher specific antibody levels. No differences in neutralising capacity were observed for the infection-naïve participants in either gender or age group. Similar to anti-Spike IgG titers, neutralising capacity decreased 3 to 9-fold at 6 months after initial vaccination for all platforms. Neutralising capacity against Omicron was between 10-58 fold lower compared to ancestral B.1 for all vaccine platforms at 21 days post dose 2 and 180 days post dose 1. This work provides evidence about the humoral response and neutralising capacity elicited by vaccination of a vulnerable elderly population. This data could be useful for pandemic management in defining public health policies, highlighting the need to apply reinforcements after a complete vaccination schedule.

Older Adults Mount Less Durable Humoral Responses to Two Doses of COVID-19 mRNA Vaccine but Strong Initial Responses to a Third Dose

BACKGROUND

Third coronavirus disease 2019 (COVID-19) vaccine doses are broadly recommended, but immunogenicity data remain limited, particularly in older adults.

METHODS

We measured circulating antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain, ACE2 displacement, and virus neutralization against ancestral and omicron (BA.1) strains from prevaccine up to 1 month following the third dose, in 151 adults aged 24-98 years who received COVID-19 mRNA vaccines.

RESULTS

Following 2 vaccine doses, humoral immunity was weaker, less functional, and less durable in older adults, where a higher number of chronic health conditions was a key correlate of weaker responses and poorer durability. One month after the third dose, antibody concentrations and function exceeded post-second-dose levels, and responses in older adults were comparable in magnitude to those in younger adults at this time. Humoral responses against omicron were universally weaker than against the ancestral strain after both the second and third doses. Nevertheless, after 3 doses, anti-omicron responses in older adults reached equivalence to those in younger adults. One month after 3 vaccine doses, the number of chronic health conditions, but not age, was the strongest consistent correlate of weaker humoral responses.

CONCLUSIONS

Results underscore the immune benefits of third COVID-19 vaccine doses, particularly in older adults.

SARS-CoV-2 Alpha-Variant Outbreak Amongst a Partially Vaccinated Long-Term Care Facility Population in The Netherlands—Phylogenetic Analysis and Infection Control Observations

Despite extensive vaccination and booster programs, SARS-CoV-2 outbreaks in long-term care facilities (LTCF) continue to occur. We retrospectively describe a SARS-CoV-2 outbreak amongst a partially vaccinated LTCF population in The Netherlands which occurred in March 2021. The facility comprised three floors functioning as separate wards. Nasopharyngeal swabs for SARS-CoV-2 qRT-PCR were obtained from residents and staff presenting with COVID-19-like symptoms and from all residents and staff during two point prevalence screenings (PPS). Samples meeting technical criteria were included for phylogenetic analysis. Positive SARS-CoV-2 qRT-PCR were obtained from 11 (18%) of 61 residents and 8 (7%) of 110 staff members between March 8 and March 25. Seven (37%) cases and five (63%) vaccinated cases were diagnosed through PPS. Cases were found on all wards. Phylogenetic analysis (n = 11) showed a maximum difference of four nucleotides between sequences on the outer branches of the tree, but identified two identical sequences on the root differing maximum two nucleotides from all other sequences, suggesting all did belong to the same cluster. Our results imply that PPS is useful in containing SARS-CoV-2 outbreaks amongst (vaccinated) LTCF populations, as an entire LTCF might behave as a single epidemiological unit and it is preferable to maximize the number of samples included for phylogenetic analysis.

Vaccination Decreases the Infectious Viral Load of Delta Variant SARS-CoV-2 in Asymptomatic Patients

The Delta variant of SARS-CoV-2 has caused many breakthrough infections in fully vaccinated individuals. While vaccine status did not generally impact the number of viral RNA genome copies in nasopharyngeal swabs of breakthrough patients, as measured by Ct values, it has been previously found to decrease the infectious viral load in symptomatic patients. We quantified the viral RNA, infectious virus, and anti-spike IgA in nasopharyngeal swabs collected from individuals asymptomatically infected with the Delta variant of SARS-CoV-2. Vaccination decreased the infectious viral load, but not the amount of viral RNA. Furthermore, vaccinees with asymptomatic infections had significantly higher levels of anti-spike IgA in their nasal secretions compared to unvaccinated individuals with asymptomatic infections. Thus, vaccination may decrease the transmission risk of Delta, and perhaps other variants, despite not affecting the amount of viral RNA measured in nasopharyngeal swabs.

Germany's fourth COVID-19 wave was mainly driven by the unvaccinated

Background

While the majority of the German population was fully vaccinated at the time (about 65%), COVID-19 incidence started growing exponentially in October 2021 with about 41% of recorded new cases aged twelve or above being symptomatic breakthrough infections, presumably also contributing to the dynamics. So far, it remained elusive how significant this contribution was and whether targeted non-pharmaceutical interventions (NPIs) may have stopped the amplification of the crisis.

Methods

We develop and introduce a contribution matrix approach based on the next-generation matrix of a population-structured compartmental infectious disease model to derive contributions of respective inter- and intragroup infection pathways of unvaccinated and vaccinated subpopulations to the effective reproduction number and new infections, considering empirical data of vaccine efficacies against infection and transmission.

Results

Here we show that about 61%-76% of all new infections were caused by unvaccinated individuals and only 24%-39% were caused by the vaccinated. Furthermore, 32%-51% of new infections were likely caused by unvaccinated infecting other unvaccinated. Decreasing the transmissibility of the unvaccinated by, e. g. targeted NPIs, causes a steeper decrease in the effective reproduction number R than decreasing the transmissibility of vaccinated individuals, potentially leading to temporary epidemic control. Reducing contacts between vaccinated and unvaccinated individuals serves to decrease R in a similar manner as increasing vaccine uptake.

Conclusions

A minority of the German population-the unvaccinated-is assumed to have caused the majority of new infections in the fall of 2021 in Germany. Our results highlight the importance of combined measures, such as vaccination campaigns and targeted contact reductions to achieve temporary epidemic control.

Humoral Immune Response of BNT162b2 and CoronaVac Vaccinations in Hemodialysis Patients: A Multicenter Prospective Cohort

The CoronaVac vaccine is the most used anti-SARS-CoV-2 vaccine worldwide. Previous data indicate that this vaccine produces a lower immune response than RNA vaccines such as BNT162b2. End-stage renal disease (ESRD) patients have an increased rate of COVID-19 and a reduced immune response to vaccinations. Currently, there is little data on this population’s immune response induced by CoronaVac. Methods: This study involved a prospective cohort of ESRD patients in chronic hemodialysis who received a two-dose immunization scheme of either CoronaVac (Sinovac Biotech) or BNT162b2 vaccines (Pfizer-BioNTech). We measured the plasma levels of anti-SARS-CoV-2 IgG antibodies. We determined antibody titers before immunization, 2 and 4 months after two doses, plus 4 months after a booster dose. Results: We evaluated 208 patients in three hemodialysis centers. The mean age was 62.6 ± 15.6 years, of whom 91 were female (41.75%). Eighty-one patients (38.94%) received the BNT162b2 vaccine and 127 (61.06%) received the CoronaVac vaccine. Patients who received the BNT162b2 vaccine had a higher humoral response compared to those who received the CoronaVac vaccine (4 months after the second dose: BNT162b2: 88.89%, CoronaVac: 51.97%, p < 0.001; 4 months after the booster: BNT162b2: 98.77%, CoronaVac: 86.61%, p < 0.001). Conclusions: Our results suggest that the CoronaVac vaccine induced a lower humoral response than the BNT162b2 vaccine in ESRD patients on hemodialysis.

SARS-CoV-2 infection, vaccination, and antibody response trajectories in adults: a cohort study in Catalonia

BACKGROUND

Heterogeneity of the population in relation to infection, COVID-19 vaccination, and host characteristics is likely reflected in the underlying SARS-CoV-2 antibody responses.

METHODS

We measured IgM, IgA, and IgG levels against SARS-CoV-2 spike and nucleocapsid antigens in 1076 adults of a cohort study in Catalonia between June and November 2020 and a second time between May and July 2021. Questionnaire data and electronic health records on vaccination and COVID-19 testing were available in both periods. Data on several lifestyle, health-related, and sociodemographic characteristics were also available.

RESULTS

Antibody seroreversion occurred in 35.8% of the 64 participants non-vaccinated and infected almost a year ago and was related to asymptomatic infection, age above 60 years, and smoking. Moreover, the analysis on kinetics revealed that among all responses, IgG RBD, IgA RBD, and IgG S2 decreased less within 1 year after infection. Among vaccinated, 2.1% did not present antibodies at the time of testing and approximately 1% had breakthrough infections post-vaccination. In the post-vaccination era, IgM responses and those against nucleoprotein were much less prevalent. In previously infected individuals, vaccination boosted the immune response and there was a slight but statistically significant increase in responses after a 2nd compared to the 1st dose. Infected vaccinated participants had superior antibody levels across time compared to naïve-vaccinated people. mRNA vaccines and, particularly the Spikevax, induced higher antibodies after 1st and 2nd doses compared to Vaxzevria or Janssen COVID-19 vaccines. In multivariable regression analyses, antibody responses after vaccination were predicted by the type of vaccine, infection age, sex, smoking, and mental and cardiovascular diseases.

CONCLUSIONS

Our data support that infected people would benefit from vaccination. Results also indicate that hybrid immunity results in superior antibody responses and infection-naïve people would need a booster dose earlier than previously infected people. Mental diseases are associated with less efficient responses to vaccination.

SARS-CoV-2 specific T cell and humoral immune responses upon vaccination with BNT162b2: a 9 months longitudinal study

The humoral and cellular immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) upon the coronavirus disease 2019 (COVID-19) vaccination remain to be clarified. Hence, we aimed to investigate the long-term chronological changes in SARS-CoV-2 specific IgG antibody, neutralizing antibody, and T cell responses during and after receiving the BNT162b2 vaccine. We performed serological, neutralization, and T cell assays among 100 hospital workers aged 22-73 years who received the vaccine. We conducted seven surveys up to 8 months after the second vaccination dose. SARS-CoV-2 spike protein-specific IgG (IgG-S) titers and T cell responses increased significantly following the first vaccination dose. The highest titers were observed on day 29 and decreased gradually until the end of the follow-up period. There was no correlation between IgG-S and T cell responses. Notably, T cell responses were detected on day 15, earlier than the onset of neutralizing activity. This study demonstrated that both IgG-S and T cell responses were detected before acquiring sufficient levels of SARS-CoV-2 neutralizing antibodies. These immune responses are sustained for approximately 6 to 10 weeks but not for 7 months or later following the second vaccination, indicating the need for the booster dose (i.e., third vaccination).