Immune Response to COVID-19 and mRNA Vaccination in Immunocompromised Individuals: A Narrative Review

Impact of Immunosuppressants and Vaccination on COVID-19 Outcomes in Autoimmune Patients and Solid Organ Transplant Recipients: A Nationwide Propensity Score-Matched Study

PURPOSE

This study investigates the impact of varying degrees of immunosuppression on the clinical outcomes of immunocompromised individuals, particularly those with autoimmune diseases or post-solid organ transplant statuses, in the context of COVID-19. By focusing on these highly vulnerable populations, the study underscores the significant health inequalities faced by immunocompromised patients, who experience disproportionately worse outcomes in comparison to the general population.

METHODS

A retrospective cohort analysis of the K-COV-N dataset was conducted, comparing the effects of immunosuppression in autoimmune and transplant groups with matched control groups. Propensity score matching was employed to minimize inequalities in baseline characteristics, ensuring a more equitable comparison between immunocompromised and non-immunocompromised individuals. Outcomes included COVID-19-related in-hospital mortality, 28-day mortality, ICU admissions, and the need for respiratory support among 323,890 adults in the Republic of Korea. Patients with cancer or other immunosuppressive conditions, such as HIV, were excluded. Subgroup analyses assessed the influence of specific immunosuppressive medications and vaccination extent.

RESULTS

Significantly elevated in-hospital mortality was found for patients with autoimmune diseases (adjusted Odds Ratio [aOR] 2.749) and transplant recipients (aOR 7.567), with similar patterns in other outcomes. High-dose steroid use and a greater number of immunosuppressant medications markedly increased the risk of poor outcomes. Vaccination emerged as a protective factor, with a single dose substantially improving outcomes for autoimmune patients and at least two doses necessary for transplant recipients.

CONCLUSIONS

Immunocompromised patients, particularly those with autoimmune diseases and transplant recipients, are highly vulnerable to severe COVID-19 outcomes. High-dose steroid use and multiple immunosuppressants further increase risks. Vaccination significantly improves outcomes, with at least one dose benefiting autoimmune patients and two doses necessary for transplant recipients. Personalized vaccination schedules based on immunosuppression levels are essential to mitigate healthcare inequalities and improve outcomes, particularly in underserved populations, informing both clinical and public health strategies.

Immunogenicity and Determinants of Antibody Response to the BNT162b2 mRNA Vaccine: A Longitudinal Study in a Cohort of People Living with HIV

BACKGROUND

The COVID-19 pandemic posed significant challenges worldwide, with SARS-CoV-2 vaccines critical in reducing morbidity and mortality. This study evaluates the immunogenicity and antibody persistence of the BNT162b2 vaccine in people living with HIV (PLWH).

METHODS

We monitored anti-SARS-CoV-2 Spike IgG concentration in a cohort of PLWH at five time points (T0-T4) using chemiluminescent microparticle immunoassays (CMIAs) at the baselined both during and after vaccination. In severely immunocompromised individuals, a boosting dose was recommended, and participants and IgG concentration were measured in the two subgroups (boosted and not boosted).

RESULTS

In total, 165 PLWH were included, and 83% were male with a median age of 55 years (IQR: 47-62). At T1, 161 participants (97.6%) showed seroconversion with a median of IgG values of 468.8 AU/mL (IQR: 200.4-774.3 AU/mL). By T2, all subjects maintained a positive result, with the median anti-SARS-CoV-2 Spike IgG concentration increasing to 6191.6 AU/mL (IQR: 3666.7-10,800.8 AU/mL). At T3, all participants kept their antibody levels above the positivity threshold with a median of 1694.3 AU/mL (IQR: 926.3-2966.4 AU/mL). At T4, those without a booster dose exhibited a marked decrease to a median of 649.1 AU/mL (IQR: 425.5-1299.8 AU/mL), whereas those with a booster experienced a significant increase to a median of 13,105.2 AU/mL (IQR: 9187.5-18,552.1 AU/mL). The immune response was negatively influenced by the presence of dyslipidaemia at T1 (aOR 4.75, 95% CI: 1.39-16.20) and diabetes at T3 (aOR 7.11, 95% CI: 1.10-46.1), while the use of protease inhibitors (aORs 0.06, 95% CI: 0.01-0.91) and being female (aOR 0.02, 95% CI: 0.01-0.32) at T3 were protective factors.

CONCLUSIONS

The immunogenicity of the BNT162b2 vaccine in PLWH has been confirmed, with booster doses necessary to maintain high levels of anti-SARS-CoV-2 Spike IgG antibodies, especially in patients with comorbidities. These findings underline the importance of a personalized vaccination strategy in this population.

Evidence synthesis and pooled analysis of vaccine effectiveness for COVID-19 mRNA vaccine BNT162b2 as a heterologous booster after inactivated SARS-CoV-2 virus vaccines

Introduction of primary COVID-19 vaccination has helped reduce severe disease and death caused by SARS-CoV-2 infection. Understanding the protection conferred by heterologous booster regimens informs alternative vaccination strategies that enable programmatic resilience and can catalyze vaccine confidence and coverage. Inactivated SARS-CoV-2 vaccines are among the most widely used vaccines worldwide. This review synthesizes the available evidence identified as of May 26, 2022, on the safety, immunogenicity, and effectiveness of a heterologous BNT162b2 (Pfizer-BioNTech) mRNA vaccine booster dose after an inactivated SARS-CoV-2 vaccine primary series, to help protect against COVID-19. Evidence showed that the heterologous BNT16b2 mRNA vaccine booster enhances immunogenicity and improves vaccine effectiveness against COVID-19, and no new safety concerns were identified with heterologous inactivated primary series with mRNA booster combinations.

Results of the Stop the Spread Ottawa (SSO) cohort study: a Canadian urban-based prospective evaluation of antibody responses and neutralisation efficiency to SARS-CoV-2 infection and vaccination

BACKGROUND

Predictors of COVID-19 vaccine immunogenicity and the influence of prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection require elucidation.

METHODS

Stop the Spread Ottawa is a prospective cohort of individuals at-risk for or who have been infected with SARS-CoV-2, initially enrolled for 10 months beginning October 2020. This cohort was enriched for public-facing workers. This analysis focuses on safety and immunogenicity of the initial two doses of COVID-19 vaccine.

RESULTS

Post-vaccination data with blood specimens were available for 930 participants. 22.8% were SARS-CoV2 infected prior to the first vaccine dose. Cohort characteristics include: median age 44 (IQR: 22-56), 66.6% women, 89.0% white, 83.2% employed. 38.1% reported two or more comorbidities and 30.8% reported immune compromising condition(s). Over 95% had detectable IgG levels against the spike and receptor binding domain (RBD) 3 months post second vaccine dose. By multivariable analysis, increasing age and high-level immune compromise predicted diminishing IgG spike and RBD titres at month 3 post second dose. IgG spike and RBD titres were higher immediately post vaccination in those with SARS-CoV-2 infection prior to first vaccination and spike titres were higher at 6 months in those with wider time intervals between dose 1 and 2. IgG spike and RBD titres and neutralisation were generally similar by sex, weight and whether receiving homogeneous or heterogeneous combinations of vaccines. Common symptoms post dose 1 vaccine included fatigue (64.7%), injection site pain (47.5%), headache (27.2%), fever/chills (26.2%) and body aches (25.3%). These symptoms were similar with subsequent doses.

CONCLUSION

The initial two COVID-19 vaccine doses are safe, well-tolerated and highly immunogenic across a broad spectrum of vaccine recipients including those working in public facing environments.

Trend of SARS-Cov-2-Specific IgG Antibody Titers Among COVID-19 Pneumonia Patients: A Nine-Month Follow-Up

Introduction Understanding the dynamics of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) spike antibody titers after natural infection is important for understanding immunological memory. This longitudinal study was conducted to assess the trend in serum SARS-CoV-2 IgG spike antibody titers in a cohort of recovered cases up to nine months after SARS infection. Materials and methods We examined the neutralizing antibody response (IgG spike) in serum samples from a cohort of 86 SARS-CoV-2 quantitative polymerase chain reaction (qPCR)-confirmed infection, comprising cases having minor COVID-19 pneumonia and severity, which was determined by CT severity scores. Patients were enrolled in August/September 2020 and serum samples have been processed at one, three, six, and nine months. CT severity scores were rated between 1-25 and antibody titers≥ 1.4 were considered positive. Results The mean anti-SARS-CoV-2-specific IgG antibody titers at one month, three months, six months, and nine months were 22.02 ± 18.36, 14.62 ± 12.61, 8.93 ± 8.10, and 3.86 ± 5.70, respectively. The difference was statistically significant. The seropositivity rates (titer ≥1.4 IU) were 93.02%, 82.56%, 76.74%, and 58.14% at one, three, six, and nine months after infection, respectively. Cases with severe CT severity scores showed significantly higher mean antibody levels at all follow-up visits.

Humoral response after a fourth dose of SARS-CoV-2 vaccine in immunocompromised patients. Results of a systematic review

Background and objective

The fourth dose the COVID-19 vaccine was first proposed to immunocompromised patients. The aim of the article is to systematically review the literature and report the humoral response and outcomes after the fourth dose administration in people with impaired immune system.

Methods

Published studies on the humoral response, efficacy and safety of the fourth dose of the COVID-19 vaccine were analyzed in various settings of immunocompromised patients. We conducted systematic searches of PubMed, Cochrane Library and WHO COVID-19 Research Database for series published through January 31, 2023, using the search terms "fourth dose" or "second booster" or "4th dose" and "Coronavirus" or "COVID-19" or "SARS-CoV-2." All articles were selected according to the PRISMA guidelines.

Results

A total of 24 articles including 2,838 patients were comprised in the systematic review. All the studies involved immunocompromised patients, including solid organ transplant recipients, patients with autoimmune rheumatic disease, patients with human immunodeficiency virus (HIV) and patients with blood cancers or diseases. Almost all patients received BNT162b2 or mRNA-1273 as fourth dose. All the studies demonstrated the increase of antibody titers after the fourth dose, both in patients who had a serological strong response and in those who had a weak response after the third dose. No serious adverse events after the 4th dose have been reported by 13 studies. COVID-19 infection after the fourth dose ranged from 0 to 21%.

Conclusion

The present review highlights the importance of the fourth dose of covid-19 vaccines for immunocompromised patients. Across the included studies, a fourth dose was associated with improved seroconversion and antibody titer levels. In particular, a fourth dose was associated with increasing immunogenicity in organ transplant recipients and patients with hematological cancers, with a very low rate of serious side effects.

Vaccine Effectiveness Against the SARS-CoV-2 B.1.1.529 Omicron Variant in Solid Organ and Islet Transplant Recipients in England: A National Retrospective Cohort Study

BACKGROUND

The effectiveness of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 Omicron variant in immunosuppressed solid organ and islet transplant (SOT) recipients is unclear.

METHODS

National registries in England were linked to identify SARS-CoV-2 positive tests, noninjury hospitalization within 14 d, and deaths within 28 d between December 7, 2020, and March 31, 2022 in adult SOT recipients. Incidence rate ratios (IRRs) for infection, and hospitalization or death, were adjusted for recipient demographics and calendar month for the Omicron-dominant period (December 20, 2021, to March 31, 2022). Mortality risk following SARS-CoV-2 infection was adjusted for recipient demographics and dominant variant using a Cox proportional-hazards model for the entire time period.

RESULTS

During the Omicron-dominant period, infection IRRs (95% confidence intervals) were higher in those receiving 2, 3, and 4 vaccine doses than in unvaccinated patients (1.25 [1.08-1.45], 1.46 [1.28-1.67], and 1.79 [1.54-2.06], respectively). However, hospitalization or death IRRs during this period were lower in those receiving 3 or 4 vaccine doses than in unvaccinated patients (0.62 [0.45-0.86] and 0.39 [0.26-0.58], respectively). Risk-adjusted analyses for deaths after SARS-CoV-2 infection between December 7, 2020, and March 31, 2022, found hazard ratios (95% confidence intervals) of 0.67 (0.46-0.98), 0.46 (0.30-0.69), and 0.18 (0.09-0.35) for those with 2, 3, and 4 vaccine doses, respectively, when compared with the unvaccinated group.

CONCLUSIONS

In immunosuppressed SOT recipients, vaccination is associated with incremental, dose-dependent protection against hospitalization or death after SARS-CoV-2 infection, including against the Omicron variant.

Humoral and T-cell response 12 months after the first BNT162b2 vaccination in solid organ transplant recipients and controls: Kinetics, associated factors, and role of SARS-CoV-2 infection

Introduction

We investigated humoral and T-cell responses within 12 months after first BNT162b2 vaccine in solid organ transplant (SOT) recipients and controls who had received at least three vaccine doses. Furthermore, we compared the immune response in participants with and without previous SARS-CoV-2 infection.

Methods

We included adult liver, lung, and kidney transplant recipients, and controls were selected from a parallel cohort of healthcare workers.

Results

At 12th-month, the IgG geometric mean concentrations (GMCs) (P<0.001), IgA GMCs (P=0.003), and median IFN-γ (P<0.001) were lower in SOT recipients than in controls. However, in SOT recipients and controls with previous infection, the neutralizing index was 99%, and the IgG, and IgA responses were comparable. After adjustment, female-sex (aOR: 3.6, P<0.009), kidney (aOR: 7.0, P= 0.008) or lung transplantation (aOR: 7.5, P= 0.014), and use of mycophenolate (aOR: 5.2, P=0.03) were associated with low IgG non response. Age (OR:1.4, P=0.038), time from transplantation to first vaccine (OR: 0.45, P<0.035), and previous SARS-CoV-2 infection (OR: 0.14, P<0.001), were associated with low IgA non response. Diabetes (OR:2.4, P=0.044) was associated with T-cell non response.

Conclusion

In conclusion, humoral and T-cell responses were inferior in SOT recipients without previous SARS-CoV-2 infection but comparable to controls in SOT recipients with previous infection.