Nucleocapsid-specific T cell responses associate with control of SARS-CoV-2 in the upper airways before seroconversion.

Despite intensive research since the emergence of SARS-CoV-2, it has remained unclear precisely which components of the early immune response protect against the development of severe COVID-19. Here, we perform a comprehensive immunogenetic and virologic analysis of nasopharyngeal and peripheral blood samples obtained during the acute phase of infection with SARS-CoV-2. We find that soluble and transcriptional markers of systemic inflammation peak during the first week after symptom onset and correlate directly with upper airways viral loads (UA-VLs), whereas the contemporaneous frequencies of circulating viral nucleocapsid (NC)-specific CD4+ and CD8+ T cells correlate inversely with various inflammatory markers and UA-VLs. In addition, we show that high frequencies of activated CD4+ and CD8+ T cells are present in acutely infected nasopharyngeal tissue, many of which express genes encoding various effector molecules, such as cytotoxic proteins and IFN-γ. The presence of IFNG mRNA-expressing CD4+ and CD8+ T cells in the infected epithelium is further linked with common patterns of gene expression among virus-susceptible target cells and better local control of SARS-CoV-2. Collectively, these results identify an immune correlate of protection against SARS-CoV-2, which could inform the development of more effective vaccines to combat the acute and chronic illnesses attributable to COVID-19.

To study the pattern of seroconversion for SARS-CoV-2 IgG antibodies in COVID-infected cancer patients and to correlate it clinically - A cross-sectional study.

Background: Though as per literature cancer is also consider an associated risk factor for morbidity and mortality for covid infection but practically most of the cancer patients showed no symptoms with less mortality in second wave of pandemic. So this cross sectional comparative analysis study was designed to see the prevalence of sero-conversion for SARS -coV for IgG in covid infected cancer patients and to compare the IgG antibodies level between covid infected cancer patients and covid infected healthy persons. Material and Method: Covid-19 antibody screening of covid recovered cancer patients as well as covid recovered healthy persons was done in department of Transfusion Medicine.IgG antibody for COVID-19 was detected using microtiter plate with whole-cell antigen coating, an in-house validated kit by NIV ICMR3. Prevalence of sero-conversion was noted down in both the groups and compared. Result: There was more infectivity rate in second covid wave. Case fatality rate was much lesser as compared to 1st wave in cancer patients. In cancer patients maximum seroconversion was seen in younger group i.e. 21-30 yrs. of age, this was in contrast to finding in general population, where minimum seroconversion was seen in younger age group. It was observed that more prevalence of sero conversion was seen in general population as compared to cancer patients, but difference was non-significant. Conclusion: Though cancer patients showed less rate of seroconversion as compared to normal healthy person, but none of them showed any moderate or severe symptoms inspite of being a risk factor for severity of covid. Though larger study are required to comment on statistical conclusion.

MERS-CoV seroconversion amongst Malaysian Hajj pilgrims returning from the Middle East, 2016-2018: results from the MERCURIAL multiyear prospective cohort study.

Prospective cohort study to investigate the potential exposure to the Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) following Hajj pilgrims is still very limited. Here, we report the antibody seroconversion study results obtained from successive three years cohort studies (2016-2018) involving the Malaysian Hajj pilgrims returning from the Middle East. A cohort study of Hajj pilgrims from Malaysia enrolled 2,863 participants from 2016-2018, all of whom consented to provide paired blood samples for both pre- and post-Hajj travel to the Middle East. ELISAs and micro-neutralization assays were performed to detect the presence of MERS-CoV IgG antibodies. Sociodemographic data, symptoms experienced during Hajj, and history of exposure to camels or camel products were recorded using structured pre- and post-Hajj questionnaires. A 4-fold increase in anti-MERS-CoV IgG between paired pre-Hajj and post-Hajj serum samples in twelve participants was observed. None of the twelve ELISA-positive sera had detectable levels of virus-neutralizing antibodies. All reportedly had mild symptoms of respiratory symptoms at a certain point during the pilgrimage, implying mild or asymptomatic infections. No association between post-Hajj serum positivity and a history of exposure to camels or camel products was obtained. Findings from the study suggest that serologic conversion to MERS-CoV occurred in at least 0.6% of the Hajj pilgrims returning from the Middle East. Since all the seroconvertants had mild to no symptoms during the sampling period, it highlights the likelihood of occurrence of only low infectivity spillover infections among the Hajj pilgrims.

COVID-19 infection and seroconversion rates in healthcare workers in Lebanon: An observational study.

Coronavirus disease 2019 (COVID-19) infection is a recent pandemic. Healthcare workers (HCW) are at high risk of acquiring the infection and transmitting it to others. Seroprevalence for COVID-19 among HCW varies between countries, hospitals in the same country and even among different departments in the same hospital. In this study, we aim to determine the prevalence of severe acute respiratory syndrome coronavirus 2 antibodies and the seroconversion among the HCW in our hospital. A total of 203 HCW were included. The rate of conversion to seropositive was 19.7% in total, with a rate of 13.4% in female versus 25% in male. The seropositivity in the House keeping group was 83%, followed by 45% in the COVID Floor while the seropositivity in the Anesthesia was 4% and the Infection Control 0%. The highest seropositivity rate in the COVID floor, and in the intensive care unit was explained by the long time spent with the patients. While in the inhalation team and the anesthesia, the lower rates of seropositivity was due to the N95 mask wearing the whole time. Seropositivity for COVID-19 in HCW is a major public health concern. Policies should be implemented to better protect HCWs.

A systematic review and meta-analysis of the seroconversion rates and adverse effects of COVID-19 mRNA vaccine and COVID-19 viral vector vaccine in kidney transplant recipient patients.

Patients received kidney transplantation (KTR) have a low seroconversion rate after vaccination. Our objective was to compare the seroconversion rates and adverse effects of additional different vaccinations in KTR patients in existing studies. Databases such as PubMed, Cochrane Library, Web of Science, Embase, ClinicalTrials.gov and others. Three high-quality RCT were included and showed no statistical difference in seroconversion rates between the two vaccines (RR = 0.93[0.76,1.13]). There was no statistical difference in seroconversion rates between the sexes, for men (RR = 0.93[0.69,1.25]) and women (RR = 0.91[0.62,1.33]). Among the adverse effects there was no statistically significant difference in fever (RR = 1.06[0.44,2.57]), while for injection site pain there was a statistically significant difference (RR = 1.14[1.18,1.84]). There was no significant difference in seroconversion rates in patients with KTR who received the two additional vaccines. Patients injected with the viral vector vaccine were less painful than those injected with the mRNA vaccine.

Seroconversion following COVID-19 vaccination: can we optimize protective response in CD20-treated individuals?

Although there is an ever-increasing number of disease-modifying treatments for relapsing multiple sclerosis (MS), few appear to influence coronavirus disease 2019 (COVID-19) severity. There is concern about the use of anti-CD20-depleting monoclonal antibodies, due to the apparent increased risk of severe disease following severe acute respiratory syndrome corona virus two (SARS-CoV-2) infection and inhibition of protective anti-COVID-19 vaccine responses. These antibodies are given as maintenance infusions/injections and cause persistent depletion of CD20+ B cells, notably memory B-cell populations that may be instrumental in the control of relapsing MS. However, they also continuously deplete immature and mature/naïve B cells that form the precursors for infection-protective antibody responses, thus blunting vaccine responses. Seroconversion and maintained SARS-CoV-2 neutralizing antibody levels provide protection from COVID-19. However, it is evident that poor seroconversion occurs in the majority of individuals following initial and booster COVID-19 vaccinations, based on standard 6 monthly dosing intervals. Seroconversion may be optimized in the anti-CD20-treated population by vaccinating prior to treatment onset or using extended/delayed interval dosing (3-6 month extension to dosing interval) in those established on therapy, with B-cell monitoring until (1-3%) B-cell repopulation occurs prior to vaccination. Some people will take more than a year to replete and therefore protection may depend on either the vaccine-induced T-cell responses that typically occur or may require prophylactic, or rapid post-infection therapeutic, antibody or small-molecule antiviral treatment to optimize protection against COVID-19. Further studies are warranted to demonstrate the safety and efficacy of such approaches and whether or not immunity wanes prematurely as has been observed in the other populations.

Predictors of Nonseroconversion after SARS-CoV-2 Infection.

Not all persons recovering from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection develop SARS-CoV-2-specific antibodies. We show that nonseroconversion is associated with younger age and higher reverse transcription PCR cycle threshold values and identify SARS-CoV-2 viral loads in the nasopharynx as a major correlate of the systemic antibody response.

Pre-Omicron seroprevalence, seroconversion, and seroreversion of infection-induced SARS-CoV-2 antibodies among a cohort of children and teenagers in Montréal, Canada.

OBJECTIVES: To use serological testing to assess the pre-Omicron seroprevalence, seroconversion, and seroreversion of infection-induced SARS-CoV-2 antibodies in children and adolescents in Montréal, Canada. DESIGN: This analysis is from a prospective cohort study of children aged 2-17 years (at baseline) that included blood spots for antibody detection. The serostatus of participants was determined by enzyme-linked immunosorbent assays using the receptor-binding domain from the spike protein and the nucleocapsid protein as antigens. We estimated seroprevalence, seroconversion rates, and the likelihood of seroreversion at 6 months and 1 year. RESULTS: The baseline (October 2020 to April 2021) seroprevalence was 5.8% (95% confidence interval [CI] 4.8-7.1), which increased to 10.5% (May to September 2021) and 11.0% (November 2021 to March 2022) for the respective follow-ups (95% CI 8.6-12.7; 95% CI 8.8-13.5). The crude rate of seroconversion over the study period was 12.8 per 100 person-years (95% CI 11.0-14.7). The adjusted hazard rates of seroconversion by child characteristics showed higher rates in children who were female, whose parent identified as a racial or ethnic minority, and in households with incomes in the lowest tercile of our study population. The likelihood of remaining seropositive at 6 months was 68% (95% CI 60-77%) and dropped to 42% (95% CI 32-56%) at 1 year. CONCLUSION: Serological studies continue to provide valuable contributions for infection prevalence estimates and help us better understand the dynamics of antibody levels after infection.

Extending the dosing interval of COVID-19 vaccination leads to higher rates of seroconversion in people living with HIV.

Introduction: Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is an effective way of protecting individuals from severe coronavirus disease 2019 (COVID-19). However, immune responses to vaccination vary considerably. This study dynamically assessed the neutralizing antibody (NAb) responses to the third dose of the inactivated COVID-19 vaccine administered to people living with human immunodeficiency virus (HIV; PLWH) with different inoculation intervals. Methods: A total of 171 participants were recruited: 63 PLWH were placed in cohort 1 (with 3-month interval between the second and third doses), while 95 PLWH were placed in cohort 2 (with 5-month interval between the second and third doses); 13 individuals were enrolled as healthy controls (HCs). And risk factors associated with seroconversion failure after vaccination were identified via Cox regression analysis. Results: At 6 months after the third vaccination, PLWH in cohort 2 had higher NAb levels (GMC: 64.59 vs 21.99, P < 0.0001) and seroconversion rate (68.42% vs 19.05%, P < 0.0001). A weaker neutralizing activity against the SARSCoV-2 Delta variant was observed (GMT: 3.38 and 3.63, P < 0.01) relative to the wildtype strain (GMT: 13.68 and 14.83) in both cohorts. None of the participants (including HCs or PLWH) could mount a NAb response against Omicron BA.5.2. In the risk model, independent risk factors for NAb seroconversion failure were the vaccination interval (hazed ration [HR]: 0.316, P < 0.001) and lymphocyte counts (HR: 0.409, P < 0.001). Additionally, PLWH who exhibited NAb seroconversion after vaccination had fewer initial COVID-19 symptoms when infected with Omicron. Discussion: This study demonstrated that the third vaccination elicited better NAb responses in PLWH, when a longer interval was used between vaccinations. Since post-vaccination seroconversion reduced the number of symptoms induced by Omicron, efforts to protect PLWH with risk factors for NAb seroconversion failure may be needed during future Omicron surges. Clinical trial registration: https://beta.clinicaltrials.gov/study/NCT05075070, identifier NCT05075070.

Monitoring SARS-CoV-2 incidence and seroconversion among university students and employees: a longitudinal cohort study in California, June-August 2020.

OBJECTIVES: To identify incident SARS-CoV-2 infections and inform effective mitigation strategies in university settings, we piloted an integrated symptom and exposure monitoring and testing system among a cohort of university students and employees. DESIGN: Prospective cohort study. SETTING: A public university in California from June to August 2020. PARTICIPANTS: 2180 university students and 738 university employees. PRIMARY OUTCOME MEASURES: At baseline and endline, we tested participants for active SARS-CoV-2 infection via quantitative PCR (qPCR) test and collected blood samples for antibody testing. Participants received notifications to complete additional qPCR tests throughout the study if they reported symptoms or exposures in daily surveys or were selected for surveillance testing. Viral whole genome sequencing was performed on positive qPCR samples, and phylogenetic trees were constructed with these genomes and external genomes. RESULTS: Over the study period, 57 students (2.6%) and 3 employees (0.4%) were diagnosed with SARS-CoV-2 infection via qPCR test. Phylogenetic analyses revealed that a super-spreader event among undergraduates in congregate housing accounted for at least 48% of cases among study participants but did not spread beyond campus. Test positivity was higher among participants who self-reported symptoms (incidence rate ratio (IRR) 12.7; 95% CI 7.4 to 21.8) or had household exposures (IRR 10.3; 95% CI 4.8 to 22.0) that triggered notifications to test. Most (91%) participants with newly identified antibodies at endline had been diagnosed with incident infection via qPCR test during the study. CONCLUSIONS: Our findings suggest that integrated monitoring systems can successfully identify and link at-risk students to SARS-CoV-2 testing. As the study took place before the evolution of highly transmissible variants and widespread availability of vaccines and rapid antigen tests, further research is necessary to adapt and evaluate similar systems in the present context.

Estimated COVID-19 vaccine effectiveness against seroconversion from SARS-CoV-2 Infection, March-October, 2021.

BACKGROUND: Monitoring the effectiveness of COVID-19 vaccines against SARS-CoV-2 infections remains important to inform public health responses. Estimation of vaccine effectiveness (VE) against serological evidence of SARS-CoV-2 infection might provide an alternative measure of the benefit of vaccination against infection. METHODS: We estimated mRNA COVID-19 vaccine effectiveness (VE) against development of SARS-CoV-2 anti-nucleocapsid antibodies in March-October 2021, during which the Delta variant became predominant. Participants were enrolled from four participating healthcare systems in the United States, and completed electronic surveys that included vaccination history. Dried blood spot specimens collected on a monthly basis were analyzed for anti-spike antibodies, and, if positive, anti-nucleocapsid antibodies. We used detection of new anti-nucleocapsid antibodies to indicate SARS-CoV-2 infection, and estimated VE by comparing 154 case-participants with new detection of anti-nucleocapsid antibodies to 1,540 seronegative control-participants matched by calendar period. Using conditional logistic regression, we estimated VE ≥ 14 days after the 2nd dose of an mRNA vaccine compared with no receipt of a COVID-19 vaccine dose, adjusting for age group, healthcare worker occupation, urban/suburban/rural residence, healthcare system region, and reported contact with a person testing positive for SARS-CoV-2. RESULTS: Among individuals who completed a primary series, estimated VE against seroconversion from SARS-CoV-2 infection was 88.8% (95% confidence interval [CI], 79.6%-93.9%) after any mRNA vaccine, 87.8% (95% CI, 75.9%-93.8%) after BioNTech vaccine and 91.7% (95% CI, 75.7%-97.2%) after Moderna vaccine. VE was estimated to be lower ≥ 3 months after dose 2 compared with < 3 months after dose 2, and among participants who were older or had underlying health conditions, although confidence intervals overlapped between subgroups. CONCLUSIONS: VE estimates generated using infection-induced antibodies were consistent with published estimates from clinical trials and observational studies that used virologic tests to confirm infection during the same period. Our findings support recommendations for eligible adults to remain up to date with COVID-19 vaccination.

Seroconversion rate after primary vaccination with two doses of BNT162b2 versus mRNA-1273 in solid organ transplant recipients: a systematic review and meta-analysis.

BACKGROUND: In the general population, the seroconversion rate after primary vaccination with two doses of an anti-severe acute respiratory syndrome coronavirus 2 messenger RNA (mRNA) vaccine reaches nearly 100%, with significantly higher antibody titers after mRNA-1273 vaccination compared to BNT162b2 vaccination. Here we performed a systematic review and meta-analysis to compare the antibody response after two-dose mRNA-1273 versus BNT162b2 vaccination in solid organ transplant (SOT) recipients. METHODS: A systematic literature review was performed using PubMed, Web of Science and the Cochrane Library and original research papers were included for a meta-analysis to calculate vaccine-specific seroconversion rates for each of the mRNA vaccines. Next, the pooled relative seroconversion rate was estimated. RESULTS: Eight studies that described the development of antibodies against receptor-binding domain (RBD) and/or spike protein were eligible for meta-analysis. Two of these studies also reported antibody titers. The meta-analysis revealed lower seroconversion rates in SOT recipients vaccinated with two doses of BNT162b2 {44.3% [95% confidence interval (CI) 34.1-54.7]} as compared with patients vaccinated with two doses of mRNA-1273 [58.4% (95% CI 47.2-69.2)]. The relative seroconversion rate was 0.795 (95% CI 0.732-0.864). CONCLUSIONS: This systematic review and meta-analysis indicates that in SOT recipients, higher seroconversion rates were observed after vaccination with mRNA-1273 compared with BNT162b2.

JCV seroconversion rate during the SARS COVID-19 pandemic.

The transmission route of the John Cunningham virus (JCV) is not clearly understood. The high prevalence of JCV in urine and sewage and the stability of the viral particles observed suggest that contaminated water, food, and fomites could be the vehicles of JCV transmission through the oral route. Multiple Sclerosis (MS) patients treated with Natalizumab are at risk of developing progressive multifocal leukoencephalopathy (PML), and hence, JCV serology is monitored for risk stratification. Social restrictions introduced in 2020 which intended to limit the transmission of SARS-CoV-2 are associated with decreased rates of other communicable diseases, as has been shown in recent observational studies. We evaluated the prevalence of seroconversion prior to and during the coronavirus disease (COVID -19) pandemic based on clinical records of JCV serology status in a single-center cohort of Natalizumab-treated Multiple Sclerosis patients. We hypothesized that seroconversion rates would decrease due to behavioral changes. However, seroconversion rates were stable during the COVID-19 pandemic compared to the pre-pandemic. These findings support the notion that JCV is transmitted via the GI tract rather than the respiratory system.

A retrospective evaluation of seroconversion after COVID-19 during the early Omicron wave in fully vaccinated multiple sclerosis patients receiving anti-CD20 therapies.

BACKGROUND: Patients with multiple sclerosis (MS) are commonly treated with anti-CD20 therapies. Reduced seroconversion following COVID-19 vaccination in patients receiving certain anti-CD20 therapies has been reported; however, the immune response following natural infection is poorly characterised. This study aimed to retrospectively evaluate COVID-19 antibody responses after vaccination and natural infection in patients treated with anti-CD20 therapies. METHODS: We performed a retrospective review evaluating COVID-19 seroconversion and anti-spike glycoprotein antibody titres in double-vaccinated patients with MS, or related neuroinflammatory conditions, treated with anti-CD20 therapies (N = 30) with a confirmed history of natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (n = 14) or without infection (control; n = 16). This single-centre study was performed at the Yale Multiple Sclerosis Center, where patients treated with anti-CD20 therapies (ocrelizumab, n = 21; rituximab, n = 5; ofatumumab, n = 4) were systematically checked for SARS-CoV-2 anti-spike antibody levels throughout the pandemic. Data were collected from March 2020 to March 2022. All patients had received at least two doses of a Food and Drug Administration (FDA)-approved COVID-19 vaccine. Qualitative anti-spike antibody seropositivity was determined based on test-specific laboratory reference ranges. For a subset of patients (n = 18), quantitative anti-spike antibody levels were assessed via DiaSorin LIAISON® chemiluminescence immunoassay (positive titre was defined as ≥ 13). Vaccination and infection dates were also recorded, and patients were monitored for adverse COVID-19-related health effects. RESULTS: Overall, 15/30 (50.0%) patients seroconverted following double vaccination. After infection, 13/14 (92.9%) seroconverted, while 6/16 (37.5%) uninfected patients seroconverted after vaccination. For the 18 patients with quantitative anti-spike antibody titres, mean titre post-vaccination was 37.4. Mean antibody titres were significantly higher after infection: 540.3 versus 20.1 in the control group (p < 0.05). Of the 14 infected patients, 13 had mild COVID-19 symptoms and one was asymptomatic. No hospitalisations or deaths were reported. CONCLUSIONS: This study reports that SARS-CoV-2 anti-spike antibody titres in double-vaccinated MS patients treated with anti-CD20 therapies were significantly increased post-infection compared with the control group. Patients treated with anti-CD20 therapy who had confirmed infections displayed mild or asymptomatic infection. These results provide reassurance that anti-CD20 therapies in double-vaccinated patients do not preclude an appropriate SARS-CoV-2 antibody response post-infection.

Exposed seronegative: Cellular immune responses to SARS-CoV-2 in the absence of seroconversion.

The factors determining whether infection will occur following exposure to SARS-CoV-2 remain elusive. Certain SARS-CoV-2-exposed individuals mount a specific T-cell response but fail to seroconvert, representing a population that may provide further clarity on the nature of infection susceptibility and correlates of protection against SARS-CoV-2. Exposed seronegative individuals have been reported in patients exposed to the blood-borne pathogens Human Immunodeficiency virus and Hepatitis C virus and the sexually transmitted viruses Hepatitis B virus and Herpes Simplex virus. By comparing the quality of seronegative T-cell responses to SARS-CoV-2 with seronegative cellular immunity to these highly divergent viruses, common patterns emerge that offer insights on the role of cellular immunity against infection. For both SARS-CoV-2 and Hepatitis C, T-cell responses in exposed seronegatives are consistently higher than in unexposed individuals, but lower than in infected, seropositive patients. Durability of T-cell responses to Hepatitis C is dependent upon repeated exposure to antigen - single exposures do not generate long-lived memory T-cells. Finally, exposure to SARS-CoV-2 induces varying degrees of immune activation, suggesting that exposed seronegative individuals represent points on a spectrum rather than a discrete group. Together, these findings paint a complex landscape of the nature of infection but provide clues as to what may be protective early on in SARS-CoV-2 disease course. Further research on this phenomenon, particularly through cohort studies, is warranted.

Torque teno virus (TTV): A gentle spy virus of immune status, predictive marker of seroconversion to COVID-19 vaccine in kidney and lung transplant recipients.

To date, no comprehensive marker to monitor the immune status of patients is available. Given that Torque teno virus (TTV), a known human virome component, has previously been identified as a marker of immunocompetence, it was retrospectively investigated whether TTV viral load may also represent a marker of ability to develop antibody in response to COVID-19-BNT162B2 vaccine in solid organ transplant recipients (SOT). Specifically, 273 samples from 146 kidney and 26 lung transplant recipients after successive doses of vaccine were analyzed. An inverse correlation was observed within the TTV copy number and anti-Spike IgG antibody titer with a progressive decrease in viremia the further away from the transplant date. Analyzing the data obtained after the second dose, a significant difference in TTV copy number between responsive and nonresponsive patients was observed, considering a 5 log10 TTV copies/mL threshold to discriminate between the two groups. Moreover, for 86 patients followed in their response to the second and third vaccination doses a 6 log10 TTV copies/mL threshold was used to predict responsivity to the booster dose. Although further investigation is necessary, possibly extending the analysis to other patient categories, this study suggests that TTV can be used as a good marker of vaccine response in transplant patients.

Seroconversion Rate After SARS-CoV-2 Infection and Two Doses of Either ChAdOx1-nCOV COVISHIELD™ or BBV-152 COVAXIN™ Vaccination in Renal Allograft Recipients: An Experience of Two Public and Private Tertiary Care Center.

Introduction: Vaccination is an effective strategy for preventing SARS-CoV-2 infection and associated mortality. Renal Transplant Recipients (RTRs) are vulnerable to acquiring infection and high mortality due to their immunocompromised state. Varying responses to the different vaccines, depending on types of vaccines and population, have been reported. Vaccines supply is also limited. The current study evaluated the seroconversion rate after SARS-CoV-2 infection and 2 doses of either COVAXIN™ or COVISHIELD™ vaccination in RTR. Methods: The serum anti-SARS-CoV-2 spike protein neutralizing antibody titer was measured in 370 RTRs who acquired SARS-CoV-2 infection (n=172), yet not vaccinated; and those vaccinated with COVAXIN™ (n=78), and COVISHIELD™ (n=120) by chemiluminescence microparticle immunoassay methods from serum. Result: Overall, the seroconversion rate either after vaccination or infection was 85.13% (315/370). The vaccine-associated seroconversion was 80.30% (159/198). SARS-CoV-2 infection-associated seroconversion was 90.69% (156/172), COVISHIELD™ associated seroconversion was 79.2% (95/120), and COVAXIN™ associated seroconversion was 82.05% (64/78). The median IgG titer in the SARS-CoV-2 infection group was 646.50 AU/ml (IQR: 232.52-1717.42), in the COVAXIN™ group was 1449.75 AU/ml (IQR: 400.0-3068.55), and the COVISHIELD™ vaccination group was 1500.51 AU/ml (IQR: 379.47-4938.50). The seroconversion rate and antibody titers were similar irrespective of the place of sampling. Patient's age-associated seroconversion in <45 years was 88.01% (213/242), 45.1-60 years was 83.18% (94/113), and > 60 years was 58.3% (7/12). Conclusions: Both infection and vaccination induce robust antibody formation in RTRs. The seroconversion rate after SARS-CoV-2 infection was higher but with a lower antibody titer than vaccines. The vaccines, COVAXIN™ and COVISHIELD™, induce more elevated antibody titers than natural infection. The seroconversion rate and antibody titer in Indian RTRs appears to be better than in the western population, irrespective of their vaccination status.

Can vitamin D status influence seroconversion to SARS-COV2 vaccines?

Existing data indicate an association between vitamin D deficiency and increased severity of respiratory distress due to COVID-19 infection, especially in high-risk populations. To date, the effect of vitamin D on immunogenicity to SARS-CoV-2 vaccines has been investigated solely in young healthcare workers in a few studies, yielding conflicting findings, yet highlighting that the response to immunization is inversely related to age. Vitamin D status can potentially influence the antibody titers in people with a previous (or naïve) SARS-CoV-2 infection and vaccination, given its role in immune regulatory functions. From this standpoint, vitamin D supplementation can help reduce the risk of SARS-CoV-2 infection, COVID-19 severity/mortality and rebalance immunological function, particularly in subjects with vigorous T lymphocyte responses to COVID-19. However, more research is needed to establish a correlation between vitamin D status and the generation of protective serological responses to SARS-CoV-2 vaccination.