Antiphospholipid antibodies in convalescent plasma of donors recovered from mild COVID-19 infection.

BACKGROUND AND OBJECTIVES: Passive immunization by the infusion of convalescent plasma (CP) obtained from patients who have recently recovered from COVID-19, thus having antibodies to severe acute respiratory syndrome coronavirus 2, is a potential strategy to reduce the severity of illness. A high prevalence of antiphospholipid antibodies (APLA) in patients with COVID-19 has been reported during the pandemic, raising a concern whether the use of CP could increase the risk of thrombosis in transfused patients. We aimed to evaluate the prevalence of APLA in COVID-19 CP (CCP) in order to assess the potential prothrombotic influence of transfused CCP to COVID-19 patients. MATERIALS AND METHODS: We studied the prevalence of APLA in 122 CCP samples collected from healthy donors who recovered from mild-COVID-19 at two time periods: September 2020-January 2021 (defined as 'early period' samples) and April-May 2021 (defined as 'late period' samples). Thirty-four healthy subjects unexposed to COVID-19 were used as controls. RESULTS: APLA were present in 7 of 122 (6%) CCP samples. One donor had anti-ß2-glycoprotein 1(anti-ß2GP1) IgG, one had anti-ß2GP1 IgM and five had lupus anticoagulant (LAC) using silica clotting time (SCT), all in 'late period' donors. In the control group, one subject had anti-ß2GP1 IgG, two had LAC using dilute Russell viper venom time (dRVVT) and four had LAC SCT (both LAC SCT and LAC dRVVT in one subject). CONCLUSION: The low prevalence of APLA in CCP donors reassures the safety of CCP administration to patients with severe COVID-19.

The effect of the third dose of the BNT162b2 vaccine on anti-SARS-CoV-2 spike antibody levels in healthcare workers with and without COVID-19 infection.

AIM: A third (booster) dose of the anti-SARS-CoV-2 vaccine became necessary due to the observed decrease in anti-SARS-CoV-2S antibody levels over time, new mutations, and low global vaccination rates. In this study, anti-SARS-CoV-2S antibody levels were measured (ECLIA assay) in 50 healthcare workers with and without a history of COVID-19 infection to determine the humoral immune response to the third dose of the BNT162b2 vaccine. METHODS: Antibody levels were determined in the blood serum, and blood was sampled for analysis 20-40 days after the administration of the booster dose. RESULTS: A greater increase in anti-SARS-CoV-2S antibody titers was noted in persons without a history of infection, but antibody levels continued to be higher in previously infected individuals when the results were adjusted for age, gender, BMI, type of work, and presence of comorbidities. CONCLUSION: The results of this study can be used to improve the vaccination strategy for the general population.KEY MESSAGESThree doses of the vaccine BNT162b2 strongly stimulate the immune system to produce anti-SARS-CoV-2s antibodies, especially in people with a previous infection COVID-19.Age, gender, and BMI may be associated with different humoral immune response to the BNT162b2 vaccine.

Leveraging Serologic Testing to Identify Children at Risk For Post-Acute Sequelae of SARS-CoV-2 Infection: An Electronic Health Record-Based Cohort Study from the RECOVER Program.

Using an electronic health record-based algorithm, we identified children with Coronavirus disease 2019 (COVID-19) based exclusively on serologic testing between March 2020 and April 2022. Compared with the 131 537 polymerase chain reaction-positive children, the 2714 serology-positive children were more likely to be inpatients (24% vs 2%), to have a chronic condition (37% vs 24%), and to have a diagnosis of multisystem inflammatory syndrome in children (23% vs <1%). Identification of children who could have been asymptomatic or paucisymptomatic and not tested is critical to define the burden of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 infection in children.

SARS-CoV-2-Spike Antibody and T-Cell Responses Elicited by a Homologous Third mRNA COVID-19 Dose in Hemodialysis and Kidney Transplant Recipients.

The effect of a third vaccine dose (3D) of homologous mRNA vaccine on blood levels of SARS-CoV-2-receptor binding domain (RBD)-total antibodies was assessed in 40 hemodialysis patients (HD) and 21 kidney transplant recipients (KTR) at a median of 46 days after 3D. Anti-RBD antibodies were detected in 39/40 HD and 19/21 KTR. Overall, 3D boosted anti-RBD antibody levels (median: 58-fold increase). Neutralizing antibodies (NtAb) against the Wuhan-Hu-1, Delta, and Omicron variants were detected in 14, 13, and 11 out of 14 HD patients, and in 5, 5, and 4 out of 8 KTR patients, respectively. The median fold increase in NtAb titers in HD patients was 77, 28, and 5 and 56, 37, and 9 in KTR patients for each respective variant. SARS-CoV-2-S S-IFN-γ-producing CD8+ and CD4+ T-cell responses were detected in the majority of HD (35 and 36/37, respectively) and all KTR (16/16) patients at 3D. Overall, the administration of 3D boosted T-cell levels in both population groups. In conclusion, a homologous mRNA COVID-19 vaccine 3D exerts a booster effect on anti-RBD antibodies, NtAb binding to Wuhan-Hu-1, Delta, and Omicron variants, and SARS-CoV-2-S-IFN-γ-producing T cells in both HD and KTR patients. The magnitude of the effect was more marked in HD than KTR patients.

Dynamics of SARS-CoV-2-Spike-reactive antibody and T-cell responses in chronic kidney disease patients within 3 months after COVID-19 full vaccination.

Background: Little is known regarding the dynamics of antibody and T-cell responses in chronic kidney disease (CKD) following coronavirus disease 2019 (COVID-19) vaccination. Methods: Prospective observational cohort study including 144 participants on haemodialysis (HD) (n = 52) or peritoneal dialysis (PD) (n = 14), those undergoing kidney transplantation (KT) (n = 30) or those with advanced CKD (ACKD) not on dialysis and healthy controls (n = 18). Anti-Spike (S) antibody and T-cell responses were assessed at 15 days (15D) and 3 months (3M) after complete vaccination schedule. HD, PD and KT patients received mRNA vaccines (mRNA-123 and BNT162b2). Most ACKD patients received BNT162b2 (n = 23), or Ad26.COV.2.S (4). Most controls received BNT162b2 (n = 12), or Ad26.COV.2.S (n = 5). Results: Anti-S antibodies at 15D and 3M were detectable in 95% (48/50)/98% (49/50) of HD patients, 93% (13/14)/100% of PD patients, 67% (17/26)/75% (21/28) of KT patients and 96% (25/26)/100% (24/24) of ACKD patients. Rates for healthy controls were 81% (13/16)/100% (17/17). Previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-S) infection was documented in four (7.7%) HD patients, two (14.3%) PD patients, two (6.7%) KT patients, one (5.55%) healthy control and in no ACKD patient. Antibody levels decreased at 3M in HD (P = .04), PD (P = .008) and ACKD patients (P = .0009). In KT patients, levels increased (P = .04) between 15D and 3M, although they were low at both time points.T-cell responses were detected in HD patients in 37 (80%) at baseline, 35 (70%) at 15D and 41 (91%) at 3M. In PD patients, T-cell responses appeared in 8 (67%) at baseline, 13 (93%) at 15D and 9 (100%) at 3M. In KT patients, T-cell responses were detected in 12 (41%) at baseline, 22 (84%) at 15D and 25 (96%) at 3M. In ACKD patients, T-cell responses were detected in 13 (46%) at baseline, 20 (80%) at 15D and 17 (89%) at 3M. None of healthy controls showed T-cell response at baseline, 10 (67%) at 15D and 8 (89%) at 3M. Conclusions: Most HD, PD and ACKD patients develop SARS-CoV-2-S antibody responses comparable to that of healthy controls, in contrast to KT recipients. Antibody waning at 3M was faster in HD, PD and ACKD patients. No differences in SARS-CoV-2 T-cell immunity responses were noticed across study groups.

Severe Acute Respiratory Syndrome Coronavirus 2 Adaptive Immunity in Nursing Home Residents Following a Third Dose of the Comirnaty Coronavirus Disease 2019 Vaccine.

A third Comirnaty vaccine dose increased severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain antibody levels (median, 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (me 22-fold), Delta, (median, 43-fold), and Omicron (median, 8-fold) variants, but had less impact on S-reactive T-cell immunity in nursing home residents.

Serosurveillance after a COVID-19 vaccine campaign in a Swiss police cohort.

INTRODUCTION: To assess the risk for COVID-19 of police officers, we are studying the seroprevalence in a cohort. The baseline cross-sectional investigation was performed before a vaccination campaign in January/February 2021, and demonstrated a seroprevalence of 12.9%. Here, we demonstrate serosurveillance results after a vaccination campaign. METHODS: The cohort consists of 1022 study participants. The 3- and 6-month follow-up visits were performed in April/May and September 2021. Data on infection and vaccination rates were obtained via measuring antibodies to the nucleocapsid protein and spike protein and online questionnaires. RESULTS: The mean age of the population was 41 (SD 8.8) years, 72% were male and 76% had no comorbidity. Seroconversion was identified in 1.05% of the study population at the 3-month visit and in 0.73% at the 6-month visit, resulting in an infection rate of 1.8% over a time period of 6 months. In comparison, the infection rate in the general population over the same time period was higher (3.18%, p = .018). At the 6-month visit, 77.8% of participants reported being vaccinated once and 70.5% twice; 81% had an anti-S antibody titer of >250 U/ml and 87.1% of ≥2 U/ml. No significant association between infection and job role within the department, working region, or years of experience in the job was found. Anti-spike antibody titers of vaccinated study participants showed a calculated decreasing trend 150-200 days after the second vaccine dose. CONCLUSION: These data confirm the value of the vaccination campaign in an exposed group other than healthcare professionals.

Evaluation of Two-Month Antibody Levels after Heterologous ChAdOx1-S/BNT162b2 Vaccination Compared to Homologous ChAdOx1-S or BNT162b2 Vaccination.

We evaluated the post-vaccination humoral response of three real-world cohorts. Vaccinated subjects primed with ChAdOx1-S and boosted with BNT162b2 mRNA vaccine were compared to homologous dosing (BNT162b2/BNT162b2 and ChAdOx1-S/ChAdOx1-S). Serum samples were collected two months after vaccination from a total of 1248 subjects. The results showed that the heterologous vaccine schedule induced a significantly higher humoral response followed by homologous BNT162b2/BNT162b2 and ChAdOx1-S/ChAdOx1-S vaccines (p < 0.0001). Moreover, analyzing factors (i.e., vaccine schedule, sex, age, BMI, smoking, diabetes, cardiovascular diseases, respiratory tract diseases, COVID-19 diagnosis, vaccine side effects) influencing the IgG anti-S response, we found that only the type of vaccine affected the antibody titer (p < 0.0001). Only mild vaccine reactions resolved within few days (40% of subjects) and no severe side effects for either homologous groups or the heterologous group were reported. Our data support the use of heterologous vaccination as an effective and safe alternative to increase humoral immunity against COVID-19.

Clinical Course of COVID-19 Disease in Children Treated With Neoplastic Diseases in Hungary.

We report on children with cancer in Hungary suffering from COVID-19, surveying a 13-months-long period of time. We performed a retrospective clinical trial studying the medical documentation of children treated in seven centers of the Hungarian Pediatric Oncology-Hematology Group. About 10% of children admitted to tertiary hemato-oncological centers for anti-neoplastic treatment or diagnosis for de novo malignancies were positive for SARS-CoV-2 infection. Nearly two-thirds of the infected patients were asymptomatic or had only mild symptoms but showed seropositivity by 1-4.5 months after positive PCR. One third of the SARS-CoV-2-positive children were hospitalized due to symptomatic COVID-19. Five children required antiviral treatment with remdesivir. One child was referred to the intensive care unit, requiring intubation and mechanical ventilation. Delay in the scheduled anti-cancer treatment did not exceed 2 weeks in the majority (89%) of cases. There was only one patient requiring treatment deferral longer than a month. There was no COVID-19-related death in patients under 18 years of age, and nor was multisystem inflammatory syndrome diagnosed. In conclusion, SARS-CoV-2 infection did not represent an untoward risk factor among children with cancer in Hungary.

HLA Class II Polymorphism and Humoral Immunity Induced by the SARS-CoV-2 mRNA-1273 Vaccine.

The vaccines designed against the SARS-CoV-2 coronavirus are based on the spike (S) protein. Processing of the S protein by antigen-presenting cells (APC) and its subsequent presentation to T cells is an essential part of the development of a humoral response. HLA-class II alleles are considered immune response genes because their codified molecules, expressed on the surface of APCs (macrophages, dendritic, and B cells) present antigenic peptides to T cell via their T cell receptor (TCR). The HLA-class II genes are highly polymorphic, regulating what specific peptides induce follicular helper T cells (TFH) and promote B lymphocyte differentiation into plasma or memory B cells. This work hypothesizes that the presence of certain HLA-class II alleles could be associated with the intensity of the humoral response (amount, length) to the SARS-CoV2 mRNA 1273 vaccine. We have studied the relationship between the HLA-class II typing of 87 health workers and the level of antibodies produced 30 days after vaccination. We show a possible association between the HLA-DRB1* 07:01 allele and the HLA-DRB1*07:01~DQA1*02:01~DQB1*02:02 haplotype to a higher production of antibodies 30 days after the administration of the second dose of mRNA-1273.

SARS-CoV-2 adaptive immunity in nursing home residents up to eight months after two doses of the Comirnaty® COVID-19 vaccine.

Burgos JS (General Directorate of Research and Healthcare Supervision, Department of Health, Valencia Government, Valencia, Spain); Meneu de Guillerna R (Vice-President Foundation Research Institute in Public Services, Valencia, Spain); Vanaclocha Luna H (General Directorate of Public Health, Department of Health, Valencia Government, Valencia, Spain); Burks DJ (The Prince Felipe Research Center-CIPF-, Valencia, Spain; Cervantes A (INCLIVA Health Research Institute, Valencia, Spain); Comas I (Biomedicine Institute of Valencia, Spanish Research Council (CSIC); Díez-Domingo J (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); Peiro S (Foundation for the promotion of health and biomedical research of the Valencian Community-FISABIO-, Valencia, Spain); González-Candelas F (CIBER in Epidemiology and Public Health, Spain; Joint Research Unit "Infection and Public Health" FISABIO-University of Valencia, Valencia, Spain; Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, Valencia, Spain); Ferrer Albiach C (Fundación Hospital Provincial de Castelló); Hernández-Aguado I (University Miguel Hernández, Alicante, Spain); Oliver Ramírez N (DataPop Alliance); Sánchez-Payá J (Preventive Medicine Service, Alicante General and University Hospital, Alicante, Spain; Alicante Institute of Health and Biomedical Research (ISABIAL), Alicante, Spain; Vento Torres M (Instituto de Investigación Sanitaria La Fe); Zapater Latorre E (Fundación Hospital General Universitario de València); Navarro D (Microbiology Service, Clinic University Hospital, INCLIVA Health Research Institute, Valencia, Spain;Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain).

Diminished and waning immunity to COVID-19 vaccination among hemodialysis patients in Israel: the case for a third vaccine dose.

BACKGROUND: Humoral responses to coronavirus disease 2019 (COVID-19) vaccines in hemodialysis (HD) patients can direct vaccination policy. METHODS: We compared 409 COVID-19-naïve HD patients from 13 HD units in Israel to 148 non-dialysis-dependent COVID-19-naïve controls. Twenty-four previously infected (antinucleocapsid positive) HD patients were analysed separately. Blood samples were obtained ≥14 days post-vaccination (BNT162b2, Pfizer/BioNTech) to assess seroconversion rates and titers of anti-spike (anti-S) and neutralizing antibodies. RESULTS: The median time from vaccination to blood sample collection was 82 days [interquartile range (IAR) 64-87] and 89 days (IQR 68-96) for HD patients and controls, respectively. Seroconversion rates were lower in HD patients compared with controls for both anti-S and neutralizing antibodies (89% and 77% versus 99.3%, respectively; P < 0.0001). Antibody titers were also significantly lower in HD patients compared with controls {median 69.6 [IQR 33.2-120] versus 196.5 [IQR 118.5-246], P < 0.0001; geometric mean titer [GMT] 23.3 [95% confidence interval (CI) 18.7-29.1] versus 222.7 [95% CI 174-284], P < 0.0001, for anti-S and neutralizing antibodies, respectively}. Multivariate analysis demonstrated dialysis dependence to be strongly associated with lower antibody responses and antibody titers waning with time. Age, low serum albumin and low lymphocyte count were also associated with lower seroconversion rates and antibody titers. HD patients previously infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had no difference in their seroconversion rates or antibody titers compared with COVID-19-naïve patients. CONCLUSION: This study demonstrates diminished and waning humoral responses following COVID-19 vaccination in a large and diverse cohort of HD patients, including those previously infected with SARS-CoV-2. Considering these results and reduced vaccine effectiveness against variants of concern, in addition to continued social distancing precautions, a third booster dose should be considered in this population.

Assessment of Post-Vaccination Antibody Response Eight Months after the Administration of BNT1622b2 Vaccine to Healthcare Workers with Particular Emphasis on the Impact of Previous COVID-19 Infection.

At the end of 2020, COVID-19 vaccination programs were initiated in many countries, including Poland. The first vaccine approved in Poland was the BNT162b2 mRNA preparation (Pfizer/BioNTech), and the first vaccinated group were healthcare workers. The aim of the present study was to evaluate post-vaccine antibody titers 8 months after the second vaccine dose had been administered to a group of employees of the Hospital of the Ministry of the Interior and Administration in Olsztyn (Poland). The employees were divided into two groups: persons who had COVID-19 in the fourth quarter of 2020 and were vaccinated in January-February 2021, and persons without a history of COVID-19 who were vaccinated during the same period. The analyzed material was venous blood serum collected from 100 hospital employees on 23-28 September 2021. The level of anti-SARS-CoV-2 S antibodies was measured with a Roche Cobas e411 analyzer using the electrochemiluminescence (ECLIA) method. The study demonstrated that persons with a history of SARS-CoV-2 infection had significantly higher antibody levels (taking into account gender, age, type of work performed, and severity of post-vaccination symptoms) than employees without a history of COVID-19. The study also revealed that the type of work, age, gender, and the course of SARS-CoV-2 infection can influence the humoral immune response. The presented results may prove helpful in the context of administering additional vaccine doses.

Approaches to the Potential Therapy of COVID-19: A General Overview from the Medicinal Chemistry Perspective.

In spite of advances in vaccination, control of the COVID-19 pandemic will require the use of pharmacological treatments against SARS-CoV2. Their development needs to consider the existence of two phases in the disease, namely the viral infection and the inflammatory stages. The main targets for antiviral therapeutic intervention are: (a) viral proteins, including the spike (S) protein characteristic of the viral cover and the viral proteases in charge of processing the polyprotein arising from viral genome translation; (b) host proteins, such as those involved in the processes related to viral entry into the host cell and the release of the viral genome inside the cell, the elongation factor eEF1A and importins. The use of antivirals targeted at host proteins is less developed but it has the potential advantage of not being affected by mutations in the genome of the virus and therefore being active against all its variants. Regarding drugs that address the hyperinflammatory phase of the disease triggered by the so-called cytokine storm, the following strategies are particularly relevant: (a) drugs targeting JAK kinases; (b) sphingosine kinase 2 inhibitors; (c) antibodies against interleukin 6 or its receptor; (d) use of the traditional anti-inflammatory corticosteroids.

Community-Based Seroprevalence of SARS-CoV-2 Antibodies following the First Wave of the COVID-19 Pandemic in Jazan Province, Saudi Arabia.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread globally, causing unprecedented effects on global health and economies. Community-based serological data are essential for understanding the true prevalence of infections, specifically the subclinical infections, as COVID-19 asymptomatic infections are common. Such data would also be important for decision making around choosing appropriate epidemiological control measures, as well as for the true estimation of mortality rates in the population. Further, determining the seroprevalence of anti-SARS-CoV-2 antibodies in the population would provide important information on herd immunity. In this study, we conducted a population-based age-stratified serological study to understand the prevalence of SARS-CoV-2 in Jazan Province, Saudi Arabia. Out of 594 participants who were recruited from 29 August to 30 December 2020, just before the vaccination rollout program in Saudi Arabia, about 157 were seropositive for SARS-CoV-2, indicating an estimated seropositivity rate of 26%. Although no significant difference in seropositivity was seen between male and female participants, we found that lower seroprevalence was associated with the younger (below 18 years old) and older populations (older than 56 years) compared with other age groups (19-55 years). These data indicate a high prevalence of SARS-CoV-2 antibodies following the peak of COVID-19 spread in Jazan province; however, most of the population (three-quarters) remains susceptible to SARS-CoV-2 infection.

Evaluation and correlation between SARS-CoV-2 neutralizing and binding antibodies in convalescent and vaccinated subjects.

Since the first detection of a novel Coronavirus (SARS-CoV-2) in December 2019 in Wuhan (China), it has become crucial to assess and quantize the human humoral immune response after SARS-CoV-2 natural infection and/or vaccination. Having well standardized and reliable serological assays able to accurately measure the total IgG antibodies response as well as the neutralization dynamics, play a pivotal role for the evaluation of "second" and "third" vaccines generation and in monitoring the effect in case of reinfection in the human population caused by the original strains or new SARS-CoV-2 variants. In the present study we reported that both symptomatic convalescent and vaccinated donors showed the presence of different levels of neutralizing antibodies. In addition, vaccinated subjects presented high levels of anti-S antibodies, whereas the complete absence of anti-N antibodies, whereas convalescent patients presented high levels of both anti-S and anti-N antibodies. The evaluation of the correlation between SARS-CoV-2 neutralizing and binding antibodies in convalescent and vaccinated subjects revealed that the IgG anti-S log-values were significantly higher in the vaccinated group respect to convalescent subjects. In addition, the level of binding antibodies recognizing the S protein shows a positive linear regression when compared to neutralizing titres in both the two groups evaluated.

Investigating Adherence to COVID-19 Vaccination and Serum Antibody Concentration among Hospital Workers-The Experience of an Italian Private Hospital.

SARS-CoV-2 transmission has been high, especially among healthcare workers worldwide during the first wave. Vaccination is recognized as the most effective approach to combat the pandemic, but hesitation to get vaccinated represents an obstacle. Another important issue is the duration of protection after administration of the full vaccination cycle. Based on these premises, we conducted a study to evaluate vaccination adherence and the anti-S antibodies levels among hospital workers, from January to March, 2021. To assess adherence, an anonymous questionnaire was used. Anti-S antibody levels were obtained from the monitoring serological sample database. In total, 56.2% of the unvaccinated people did not report a previous infection from COVID-19. Among those who have not been vaccinated, 12.5% showed distrust against the vaccine, 8.3% stated to have received contraindications to the vaccination, and 6.3% did not report any choice. Analyzing anti-S antibody levels, only one person was found to have a value below the lower cut-off, two weeks, and three months after receiving their second dose. One was below the cut-off after two weeks, and then above the same cut-off after three months. The results of our survey should be seen as a stimulus to further sensitize hospital staff to the importance of vaccination and pay attention to anti-S antibody levels monitoring.

Immunological response against SARS-CoV-2 following full-dose administration of Comirnaty® COVID-19 vaccine in nursing home residents.

OBJECTIVES: The current study was aimed at examining SARS-CoV-2 immune responses following two doses of Comirnaty® COVID-19 vaccine among elderly people in nursing homes. METHODS: A prospective cohort study in a representative sample from nursing homes in Valencia (n = 881; males: 271, females 610; median age, 86 years) recruited residents using a random one-stage cluster sampling approach. A lateral flow immunochromatography device (LFIC) (OnSite COVID-19 IgG/IgM Rapid Test; CTK BIOTECH, Poway, CA, USA) was used as the front-line test for detecting SARS-CoV-2-Spike (S)-specific antibodies in whole blood obtained using a fingerstick. Residents returning negative LFIC results underwent venipuncture and testing for presence of SARS-CoV-2-S-reactive antibodies and T cells using the Roche Elecsys® Anti-SARS-CoV-2 S (Roche Diagnostics, Pleasanton, CA, USA), the LIAISON® SARS-CoV-2 TrimericS IgG assay (Diasorin S.p.A, Saluggia, Italy) and by flow cytometry, respectively. RESULTS: The SARS-CoV-2-S antibody detection rate in nursing home residents was 99.6% (283/284) and 98.3% (587/597) for SARS-CoV-2 recovered and naïve residents, respectively, within a median of 99 days (range 17-125 days) after full vaccination. Three out of five residents lacking SARS-CoV-2-S antibodies had detectable S-reactive CD8+ and/or CD4+ T cells. In addition, 50/50 and 40/50 participants with detectable SARS-CoV-2 antibodies also had SARS-CoV-2-S-reactive interferon-γ-producing CD4+ and CD8+ T cells, respectively. DISCUSSION: The Comirnaty® COVID-19 vaccine is highly immunogenic in nursing home residents.

B- and T-cell immune responses elicited by the Comirnaty® COVID-19 vaccine in nursing-home residents.

OBJECTIVES: The immunogenicity of the Comirnaty® vaccine against coronavirus disease 2019 (COVID-19) has not been adequately studied in elderly people with comorbidities. We assessed antibody and T-cell responses targeted to the S protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) following full vaccination in nursing-home residents. METHODS: Sixty nursing-home residents (44 female, age 53-100 years), of whom ten had previously been diagnosed with COVID-19, and 18 healthy controls (15 female, age 27-54 years) were recruited. Pre- and post-vaccination blood specimens were available for quantification of total antibodies binding the SARS-CoV-2 S protein and for enumeration of SARS-CoV-2 S-reactive IFN-γ CD4+ and CD8+ T cells by flow cytometry. RESULTS: The seroconversion rate in (presumably) SARS-CoV-2-naïve nursing-home residents (41/43, 95.3%) was similar to that in controls (17/18, 94.4%). A booster effect was documented in post-vaccination samples of nursing-home residents with prior COVID-19. Plasma antibody levels were higher (p < 0.01) in recovered nursing-home residents (all 2500 IU/mL) than in individuals across the other two groups (median 1120 IU/mL in naïve nursing-home residents and 2211 IU/ml in controls). A large percentage of nursing-home residents had SARS-CoV-2 S-reactive IFN-γ CD8+ (naïve 31/49, 63.2%; recovered 8/10, 80%) or CD4+ T cells (naïve 35/49, 71.4%; recovered 7/10, 70%) at baseline, in contrast to healthy controls (3/17, 17.6% and 5/17, 29%, respectively). SARS-CoV-2 IFN-γ CD8+ and CD4+ T-cell responses were documented in 88% (15/17) and all control subjects after vaccination, respectively, but only in 65.5% (38/58) and 22.4% (13/58) of nursing-home residents. Overall, the median frequency of SARS-CoV-2 IFN-γ CD8+ and CD4+ T cells in nursing-home residents decreased in post-vaccination specimens, whereas it increased in controls. CONCLUSION: The Comirnaty COVID-19 vaccine elicits robust SARS-CoV-2 S antibody responses in nursing-home residents. Nevertheless, the rate and frequency of detectable SARS-CoV-2 IFN-γ T-cell responses after vaccination was lower in nursing-home residents than in controls.