1Division of Neurology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 2Siriraj
Neuroimmunology Center, Division of Neurology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 3Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, 4Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 5Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 6Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 7Division of Infectious disease and tropical medicine, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand, 8Bumrungrad International Hospital, Bangkok 10110, Thailand.
ABSTRACT
Corresponding author: Sasitorn Siritho E-mail: siritho@yahoo.com
Received 7 December 2023 Revised 26 December 2023 Accepted 26 December 2023 ORCID ID:http://orcid.org/0000-0002-2562-697X https://doi.org/10.33192/smj.v76i2.266638
All material is licensed under terms of the Creative Commons Attribution 4.0 International (CC-BY-NC-ND 4.0) license unless otherwise stated.
INTRODUCTION
The Coronavirus Disease-19 (COVID-19) pandemic has prompted mass vaccination efforts worldwide. Numerous novel vaccines against the severe acute respiratory syndrome-related coronavirus 2 (SARS- CoV-2) have been engineered. The platforms used range from inactivated viruses to protein subunits, viral vectors, and messenger ribonucleic acid (mRNA). Studies in general populations have shown variable vaccine efficacy and adverse events following immunization related to the vaccine with each regimen of vaccine.1-3 However, patients using immunosuppressive agents as a special very high risk of COVID-19 population were excluded from pivotal phase III vaccine trials.4
Immune-mediated neurological diseases, such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and other autoimmune neurological diseases (AINDs), are rare diseases.5,6 The cornerstone of management of immune-mediated neurological diseases is immunomodulatory and immunosuppressive therapies, which are known as immunotherapies (IMTs). Examples include azathioprine (AZA), mycophenolate mofetil (MMF), and rituximab (RTX), which are sometimes used as an alternative to immunomodulators, especially in resource-limited settings.7,8 AZA and MMF are anti- metabolites that decrease T and B lymphocyte proliferation while RTX specifically suppresses B lymphocytes targeting CD20. While achieving disease control, these agents need to be monitored for their immunosuppressive effects, which could confer greater susceptibility to infection.9 Some studies have observed a lower immune response
to COVID-19 vaccines in patients taking immunosuppressive agents compared to healthy controls.10 Low immunoglobulin levels due to B lymphocyte suppression could attenuate vaccine responsiveness, particularly among those taking anti-CD20 RTX.11 Measurement of specific immunity to SARS-CoV-2, including IgG to a receptor-binding domain (anti-RBD IgG), neutralizing antibody (NAbs), and interferon-gamma release assay (IGRA) could be quantitative surrogate markers for vaccine efficacy. Therefore, we aimed to compare the immune responses after each regimen of COVID-19 vaccination between patients with AIND and a healthy control population.
MATERIALS AND METHODS
Participants and samples
This prospective observational study was conducted at Siriraj Hospital, a university hospital referral center in Thailand. Sera from patients with AIND attending the Neurology Clinic at Siriraj Hospital from December 2021 to July 2022 were collected one week before and
one month after the COVID-19 vaccination.
The inclusion criteria were age greater than 18 years and receiving at least two doses of COVID-19 vaccination. Patients lost to follow-up or not able to give post-vaccination sera were excluded. Also, those with a history of COVID-19 infection in the past 6 months or anti-RBD IgG seropositivity at baseline were excluded. Patients with AIND recruited into the study were matched with healthy controls receiving a vaccine against COVID-19 to compare their responsiveness to the vaccine regimens.
Clinical data, including sex, diagnosis, age at disease onset, disease duration, the total number of previous attacks before the first COVID-19 vaccination, current IMT, the number of prior IMTs used, and the most recent follow-up Expanded Disability Status Scale (EDSS) were collected. COVID-19 vaccination status, platforms used, and doses received were documented. We performed matching healthy controls by age, sex, and vaccination regimen.
Participants in the healthy control group were healthy adults aged ≥ 18 years in whom sera were collected from two prospective cohort studies of vaccination of either two doses of CoronaVac or two doses of ChAdOx112, and third-dose booster vaccination either BBIBP-CorV, ChAdOx1, 30μg-BNT162b2, or 15μg-BNT162b2.13 All patients were informed the information about each vaccine and their possible adverse events according to the government brochure.
We defined groups of vaccines for comparison. We defined inactivated vaccine regimen as those having received two doses of an inactivated vaccine. We defined vector-based vaccine regimen as those having received two doses of vector-based vaccines, one dose of each of an inactivated and a vector-based vaccine, and vector- based vaccine as the third dose. Finally, we defined mRNA vaccine regimen as those having received two doses of mRNA vaccine and mRNA vaccine as the third dose.
All participants received their COVID-19 vaccination regimens according to the availability of the vaccines at that time, each patient’s preference, and the Thai Ministry of Public Health’s recommendations.14 Most Thai people received a mix-and-match, prime-boost immunization strategy.
The Siriraj Institutional Review Board approved this study (COA no. Si 707/2021). All patients gave written informed consent. The study was performed in accordance with the Declaration of Helsinki of 1975.
Serum immunologic testing
Serum immunologic tests were anti-RBD IgG assay15,
NAbs assay16, and interferon SARS-CoV-2 immunoassay.17,18 We defined an anti-RBD IgG assay titer level of greater or equal to 7.1 BAU/mL as seropositive. The cut off value for inhibition response was set at 30%. The cut-off value for Ag1-Nil and Ag2-Nil was set at 0.2 IU/mL.18 The details for each test are described in the Appendix.
Statistical analysis
We analyzed the data descriptively. Categorical data are displayed as frequency (%), and continuous data are displayed as median (interquartile range [IQR]). Categorial data was analyzed by the χ2 test or Fisher’s exact test if less than 75% of cells had expected frequencies of greater than five. Continuous data were compared by nonparametric, rank-based Mann-Whitney U test for pairwise testing or the Kruskal Wallis test if there were more than two groups to compare. Pre- and post-vaccination anti-RBD IgG levels were compared by Wilcoxon signed-rank test for non-parametric, non-independent data. All data were analyzed on PASW Statistics for Windows version 18.0 (SPSS Inc., Chicago, IL) and Graphpad Prism version 9 (GraphPad Software, San Diego, CA).19 A p-value of less than 0.05 was considered significant. No correction for multiplicity was applied.
RESULTS
Sixty-one patients with AIND were recruited. Three were excluded due to evidence of prior COVID-19 infection (history of COVID-19 infection three months
before eligibility assessment n = 1 and anti-RBD-IgG seropositivity n = 2). Thus, 58 patients were included in the final analysis (having received inactivated vaccine regimen n = 15, having received a vector-based vaccine regimen n = 31, and having receive a mRNA vaccine regimen n = 22). Of the 58 patients, 46 (78.3%) were female. All 58 patients were evaluated for anti-RBD IgG. The T cell response test was performed in only 22 patients due to limited availability. Thirty-five patients with anti-RBD IgG positivity received further testing for NAbs. Fourteen patients were tested for
all the three immunity assays (Fig 1).
Of the 58 patients, the frequencies of immunotherapy status were no immunotherapy (n = 6), azathioprine (n = 15), MMF (n = 13), rituximab (n = 18), fingolimod (n = 4), glatiramer acetate (n = 1), and prednisolone (n = 1). Diagnoses included were NMOSD (n = 27), MS (n = 15), myasthenia gravis (MG) (n = 5), clinically isolated syndrome (n = 4) [idiopathic single transverse myelitis (n = 2), isolated demyelinating brainstem syndrome (n = 1), and single optic neuritis (n = 1)], autoimmune encephalitis (n = 3) [anti-N-methyl D-aspartate encephalitis (n = 2) and seronegative autoimmune encephalitis (n = 1)], pachymeningitis (n = 3) [eosinophilic granulomatosis with polyangiitis with pachymeningitis (n = 1), idiopathic pachymeningitis (n = 1), and IgG4-related pachymeningitis (n = 1)], and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) (n = 1). All groups of patients had similar age at onset,
Notes: Data were available as the following: 58 patients had anti-RBD IgG level, 35 patients had neutralizing antibodies, and 22 patients had T cell responses.
Abbreviations: AINDs, autoimmune neurological diseases; RBD, receptor-binding domain
EDSS scores, interval from disease onset to the third dose of vaccination, interval from the most recent treatment initiation to the third dose of vaccine administration, and concomitant diseases. Conversely, interval from disease onset to the second dose vaccination and interval from the latest treatment initiation to the second vaccine were significantly different (both p < 0.05) (Table 1).
Anti-RBD IgG Response to the SARS-CoV2 Virus
Forty-nine patients had anti-RBD antibodies testing after their second dose of COVID-19 vaccination, of which 15 patients had received two doses of an inactivated vaccine (either CoronaVac or BBIBP-CorV COVID-19 vaccine), 27 patients had received two doses of the vector-based ChAdOx1 nCoV-19 vaccine, 4 patients had received two doses of an mRNA vaccine (either the mRNA- 1273 SARS-CoV-2 vaccine or the BNT162b2 nCoV-19 vaccine), and 3 patients had received combinations of CoronaVac and ChAdOx1 nCoV-19. Of the 49 patients, 11 patients had additional anti-RBD antibody testing after the third vaccination. The remaining 9 of the 58 patients had anti-RBD antibody testing performed after the third vaccination. (Fig 1)
Comparison of Anti-RBD IgG Responses by Vaccine Regimen
Only 13 patients had data on pre-vaccination anti- RBD antibodies levels. Of these, 10 (76.9%) demonstrated a 23-fold rising in antibody titer compared with the baseline value with a median anti-RBD level of 0.21 BAU/mL (IQR 0.16-0.43) pre-vaccination and 4.81
BAU/mL (IQR 0.17- 33.41) post-vaccination (p = 0.013). (Supplementary Fig S1)
After the second vaccination, 29 of 49 (59.2%) patients had rising antibody titers above the cut point for seropositivity with a median level of 15.25 BAU/mL (IQR 0.47-152.11).
mRNA vaccine regimens seemed to induce higher anti-RBD levels than the vector-based vaccine regimens, and inactivated vaccine regimen demonstrated the least immunogenicity. For all 68 sera of 58 patients included in the final analysis, the seropositive rates for inactivated vaccine, vector-based vaccine, and mRNA vaccine regimens for anti-RBD were 26.7% (4 of 15), 71% (22 of 31), and
72.7% (16 of 22), respectively. For inactivated vaccine, vector-based vaccine, and mRNA vaccine regimens, the median levels were 0.58 BAU/mL (IQR 0.24-7.50),
52.82 BAU/mL (IQR 5.61-171.79), and 969.77 BAU/mL
(IQR 3.41-2382.53) BAU/mL, respectively (p < 0.001). (Fig 2A)
The NMOSD group demonstrated the highest anti- RBD IgG level for mRNA vaccine regimens [1062.87 BAU/mL (IQR 93.29-2151.47)], followed by vector- based vaccine regimens [106.22 BAU/mL (IQR 51.39- 298.21)], and inactivated vaccine regimens [3.01 BAU/ mL (IQR 0.18-91.50)], respectively (p = 0.030) (Fig 2B). Conversely, MS patients did not demonstrate any significant difference among mRNA regimens, vector-based regimens, and inactivated vaccine regimens with median levels at 2.78 BAU/mL (IQR 0.39-3803.75), 5.61 BAU/mL
(IQR 0.20-14.00), and 0.36 BAU/mL (IQR 0.21-7.50),
respectively (p = 0.666) (Fig 2C). Similarly, patients in the other AINDs group did not demonstrate any significant differences across all vaccine regimens with median levels at 937.88 BAU/mL (IQR 51.30- 5196.40) for mRNA regimens, 28.41 BAU/mL (IQR 2.51-135.64) for vector-based regimens, and 1.33 BAU/mL (IQR 0.41-34.93) for inactivated vaccine regimens (p = 0.069) (Fig 2D).
Comparison of Anti-RBD IgG Responses by Type of Immunotherapy
Compared to the no IMT/heathy control group, patients treated with RTX having received inactivated vaccine regimen showed a significant reduction of anti- RBD response [112.54 BAU/mL (IQR 53.30-171.32) vs.
0.26 BAU/mL (IQR 0.12-0.36); p = 0.010]. (Fig 2E)
For those having received a vector-based vaccine regimen, compared to the no IMT/healthy control group, significant reductions of anti-RBD IgG responses were observed in those treated with RTX, FGM, and MMF [no IMT/healthy controls 235.03 BAU/mL (IQR 96.07- 405.77) vs. each of RTX 0.42 BAU/mL (IQR 0.06-61.21);
p = 0.002, FGM 4.81 BAU/mL (IQR 0.20-5.61); p < 0.001,
and MMF 50.91 BAU/mL (IQR 8.18-71.86); p = 0.001].
However, no significant reduction was seen comparing no IMT/healthy controls to AZA. (Fig 2F)
For those having received an mRNA vaccine regimen, the no IMT/healthy controls had a remarkably higher anti-RBD-IgG level [4633.13 BAU/mL (IQR 2256.71-
7415.94)]. In comparison to the no IMT/healthy controls, RTX showed a significant reduction in anti-RBD level [0.34 BAU/mL (IQR 0.14-49.58); p = 0.010] while the
FGM group showed some reduction without significance [0.77 BAU/mL (IQR 0.01-1.53); p = 0.133]. (Fig 2G)
Neutralizing antibodies for delta and omicron variants
Amongst the 35 patients seropositive for anti-RBD IgG, 41 serum samples were further evaluated for NAbs against specific COVID-19 variants.
TABLE 1. Demographic and characteristics of patients with AINDs
Characteristics | No immunotherapy | Azathioprine | MMF | RTX | Fingolimod | Other: Glatiramer acetate, Prednisolone | P-value |
(n = 6) | (n = 15) | (n = 13) | (n = 18) | (n = 4) | (n = 2) | ||
Female gender, n (%) | 6 (100) | 14 (93.3) | 13 (100) | 10 (55.6) | 2 (50) | 1 (50) | 0.003 |
Age at onset, median (range), y | 53.5 (29.3, 63.8) | 45.0 (35.0, 55.0) | 44.0 (26.5-50.5) | 35.5 (21.3, 43.8) | 38.5 (28.5, 47.0) | 40.5 | 0.447 |
EDSS†¥, median (range) | 1.25 (1.00, 5.63) | 1.0 (1.0, 1.5) | 1.25 (1, 4.12) | 1 (0, 3.38) | 1.0 (0.25, 2.50) | 1.0 (1.0, 1.0) | 0.799 |
Duration from disease onset to vaccine administration, median (interquartile range), month | |||||||
To 2nd dose | 119.34 (NA) | 93.8 | 123.98 | 47.9 | 81.9 | 4.73 (NA) | 0.027 |
(29.3, 141.4) | (50.3, 206.1) | (21.2, 87.6) | (36.2, 137.9) | ||||
To 3rd dose | 23.1 | 129.94 (NA) | 149.8 | 47.2 | 92.76 (NA) | 5.82 (NA) | 0.166 |
(20.4, 109.5) | (59.3, 240.2) | (32.2, 74.4) | |||||
Duration from the latest treatment initiation to vaccine administration‡, median (interquartile range), month | |||||||
To 2nd dose | NA | 2.72 (1.77, 3.73) | 2.72 (0.46, 3.79) | 6.80 (3.22, 7.52) | 1.91 (1.47, 2.07) | 1.97 (NA) | 0.002 |
To 3rd dose | NA | 7.92 (NA) | 7.56 (5.63, 8.95) | 9.96 (8.81, 23.2) | 5.90 (NA) | 7.00 | 0.055 |
Comorbidities¶, n (%) | 4 (66.7) | 9 (60) | 7 (53.8) | 6 (33.3) | 4 (100) | 1 (50) | 0.198 |
Current disease, n (%) | |||||||
MS | 1 (16.7) | 2 (13.3) | 2 (15.4) | 5 (27.8) | 4 (100) | 1 (50) | 0.018 |
NMO | 1 (16.7) | 9 (60) | 8 (61.5) | 9 (50) | 0 | 0 | 0.089 |
Others AIND* | 4 (66.7) | 4 (26.7) | 3 (23.1) | 4 (22.2) | 0 | 1 (50) | 0.239 |
Number of attacks#, median (range) | 1.0 (1.0, 2.75) | 1.0 (1.0, 5.0) | 3.0 (2.0, 10.5) | 2.0 (1.0, 3.25) | 2.0 (2.0, 3.5) | 1.0 (1.0, 1.0) | 0.094 |
Vaccine regimen, n (%) | |||||||
Inactivated vaccine regimen | 0 | 4 (26.7) | 4 (30.8) | 6 (33.3) | 1 (25.0) | 0 | 0.194 |
Vector-based vaccine regimen | 2 (20.0) | 9 (60.0) | 7 (53.8) | 8 (44.4) | 3 (75.0) | 2 (100) | 0.035 |
mRNA vaccine regimen | 4 (80.0) | 4 (26.7) †† | 6 (46.2) ‡‡ | 6 (33.3) §§ | 2 (50.0) | 0 | 0.848 |
Serum immunologic testing, n (%) | |||||||
Tested for RBDs | 6 (100) | 15 (100) | 13 (100) | 18 (100) | 4 (100) | 2 (100) | 1 |
Tested for NAbs** | 5 (83.3) | 15 (100) | 8 (61.5) | 6 (33.3) | 0 (0) | 1 (50.0) | <0.001 |
Tested for IGRA | 3 (50.0) | 3 (20.0) | 6 (46.2) | 7 (38.9) | 2 (50.0) | 1 (50.0) | 0.623 |
Abbreviations: AINDs, autoimmune neurological diseases; EDSS, Expanded Disability Status Scale; IGRAInterferon SARS-CoV-2; IS, immunosuppressive; MS, multiple sclerosis; NAbs, neutralizing antibodies; NMOSD, neuromyelitis optica spectrum disorder; RBDs, anti-RBD IgG level
*Clinical findings of other patients consisted of myasthenia gravis (n = 5), autoimmune encephalitis (n = 3), MOGAD (n = 1), pachymeningitis (n = 2), and clinically isolated syndromes (n = 5)
†EDSS scores were evaluated in MS and NMOSD patients at the last visit before blood drawing for assay testings¥EDSS scores available in 44 patients
‡For patients receiving immunotherapy
§Of 51 patients, 2 received no immunotherapy
‖Of 20 patients, 4 received no immunotherapy
¶Comorbidities included diabetes mellitus, hypertension, dyslipidemia, vitamin D deficiency, obstructive sleep apnea, obesity, cirrhosis, systemic lupus erythematosus,
Hashimoto thyroiditis, coronary artery disease, thymoma, herpes keratoconjunctivitis, and osteoarthritis
#The number of attacks was evaluated in MS and NMOSD patients
**Only patients with positive anti-RBD responses further analysis for neutralizing antibody response
††2 patients received vector-based vaccine as the first two doses and mRNA vaccine for third vaccine dose.
‡‡4 patients received vector-based vaccine as the first two doses and mRNA vaccine for third vaccine dose.
§§1 patient received vector-based vaccine as the first two doses; 1 patient received inactivated vaccine as the first two doses; and both received mRNA vaccine for third vaccine dose.
Notes for figures A-D:- (A) All AINDs, (B) NMOSD, (C) MS, and (D) other AINDs.
Notes for figures E-G:- Groups compared were healthy control or no immunotherapy, azathioprine, mycophenolate mofetil, rituximab, and fingolimod(E) two doses of any vaccines, (F) three doses of any vaccines. Statistical significance was calculated by the Mann–Whitney U test. The anti-RBD IgG cut-off value (dash line) was 7.1 BAU/mL. *denotes a statistically significant result at the p < 0.05 level.
Abbreviations: RBD, receptor-binding domain; AINDs, autoimmune neurological diseases; NMOSD, neuromyelitis optica spectrum disorder; MS, multiple sclerosis; HC, healthy control; IMT, immunotherapy
Inhibition percentage categorized by vaccine regimen
The overall median inhibition percentages were higher in the Delta variant than the Omicron one regardless of vaccine regimen [53.84% (IQR 20.69-94.40) vs. 8.59%
(IQR 6.05-23.09); p < 0.001].
The median NAbs inhibition percentage for the Delta variant was the highest in mRNA vaccine regimens [97.63% (80.77, 98.00)], followed by vector-based vaccine
regimens [30.76% (IQR 13.48-80.32)], and inactivated
vaccine regimens [22.3% (IQR 2.94-38.92)], respectively (p < 0.001). There were significant pairwise differences between mRNA and inactivated vaccine regimens (p = 0.004) along with between mRNA and vector-based
vaccine regimens (p < 0.001). (Fig 3A)
The same pattern was mostly seen in the Omicron variant. mRNA vaccine regimens had the highest median inhibition percentage [25.94% (IQR 11.15-70.84)], followed by vector-based regimens [7.69% (IQR 5.44-11.67)] and inactivated vaccine regimens [6.05 (IQR 5.77-8.13)] (p = 0.005). Also, there was a significant pairwise difference between mRNA vaccines and vector-based vaccines (p = 0.010) and a trend to significance between mRNA vaccine regimens and inactivated vaccine regimens (p = 0.056). None of the regimens showed an inhibition percentage greater than 30% for the Omicron variant. (Fig 3B)
Notes for figures A-B:- Nonparametric distributions are displayed as median (interquartile range) by bar and error bar, respectively. The cut off value (dashed line) for inhibition response was set at 30%. Statistical significance was calculated by the Kruskal-Wallis test. *denotes a statistically significant result at the p < 0.05 level.
Notes for figures C and D:- Nonparametric distributions are displayed as median (interquartile range) by bar and error bar, respectively. Statistical significance was calculated by the Mann–Whitney U test. *denotes a statistically significant result at the p < 0.05 level.
The cut-off value (dashed line) for inhibition response was set at 30%.
Inhibition percentage categorized by type of immunotherapy
Patients tested for the Delta variant showed a significantly greater median inhibition percentage than the Omicron variant across all IMTs (p < 0.001). Compared to the no IMT group [92.74% (IQR 87.88-98.15)], AZA and
RTX groups showed significant attenuation of inhibition
percentages against the Delta variant [AZA 60.04% (IQR 19.87-83.22); p = 0.009] and RTX 30.29% (IQR 9.06-
34.93); p = 0.018] (Fig 3C). For the Omicron variant, the no IMT group showed no significant difference in inhibition percentages compared with either IMT use groups. (Fig 3D)
T cell Responses to the SARS-CoV2 Virus
Twenty-two patients with 23 serum samples were tested for T cell responses with seven samples tested after the second vaccination, and 16 samples tested after the third vaccination. One patient was tested after the second and third dose of vaccination.
The T cell response did not significantly differ between the second and third vaccination; Ag1-Nil 0.21 IU/mL (IQR -0.01-1.88) vs. 0.23 IU/mL (IQR -0.03-3.59), p = 0.343 and Ag2-Nil 0.22 IU/ml (IQR 0.00-2.41) vs.
0.57 IU/mL (IQR -0.05-8.67), p = 0.131, respectively.
T cell Responses Categorized by Vaccine Regimen
T cell response measured by Ag1-Nil and Ag2-Nil were no significantly different across all vaccine regimes (p = 0.346 for Ag1-Nil and p = 0.297 for Ag2-Nil). The mRNA vaccine regimens had the highest positive rates for Ag1-Nil response at 64.71% (11 of 17) compared
with 60% (3 of 5) in vector-based regimens and 0% (0 of 1) in inactivated vaccine regimens. However, the positive rate for Ag2-Nil response was the highest in vector-based vaccine regimens at 80% (4 of 5), followed
by 12 of 17 (70.59%) in mRNA regimens, and 0% (0/1) in inactivated vaccine regimen. (Fig 4A-4B)
Anti-CD20 Therapy Demonstrates Similar T cell Responses to Non-anti-CD20 Treatment
Among the group treated with no IMTs (n = 3), anti-CD20 RTX (n = 7), and non-anti-CD20 therapy (n = 13), both Ag1-Nil and Ag2-Nil revealed no significant differences (1.37 IU/mL [IQR 0.47-1.88], 0.19 IU/mL
[IQR 0.08-0.98], and 0.24 IU/mL [IQR 0.01-0.50];
p = 0.210 for Ag-1 Nil, and 2.41 IU/mL [IQR 1.32-2.42],
0.40 IU/mL [IQR 0.11-1.52], and 0.38 IU/mL [IQR 0.04-
1.03]; p = 0.193 for Ag2-Nil, respectively). (Fig 4C-4D)
Notes for figures 4A-4D:- Nonparametric distributions are displayed as median (interquartile range) by bar and error bar, respectively. The cut-off value (dashed line) for Ag1-Nil and Ag2-Nil was set at 0.2 IU/mL. Statistical significance was calculated by the Kruskal-Wallis test.
*denotes a statistically significant result at the p < 0.05 level.
All anti-RBD IgG assays, neutralizing antibody assays, and interferon SARS-CoV-2 immunoassays were categorized by disease. The details for each immune response are described in the Results section and Supplementary Fig S2 in the Supplementary Appendix.
DISCUSSION
Our study shows COVID-19 vaccination augments the immune system in both T cell functions and B cell functions, demonstrated by anti-RBD IgG, surrogate NAbs, and interferon SARS-CoV-2 immunoassay. The response differed depending on the vaccine regimen, the IMT type, and the variant of COVID-19.
Similar to previous studies, vaccination platforms played a role in the responsiveness of antibodies.20 Our study also showed inactivated vaccine regimens induced the lowest response as in Fig 2 and 3. mRNA vaccine regimens showed a significantly higher antibody response compared with inactivated and vector-based vaccine regimens among patients with central nervous system immunological diseases measured by the anti-RBD IgG antibody.
Compared to those with no IMT or healthy controls, there was a significant reduction of anti-RBD IgG levels in patients treated with RTX in all vaccine regimens.
The present study also showed neutralizing activity against SARS-CoV-2 measured by NAbs depended on the variant. The overall median inhibition percentages were higher for the Delta variant than for the Omicron variant regardless of vaccine regimen group and type of IMT used. However, for the Omicron variant, those having received an inactivated vaccine, a vector-based vaccine, or an mRNA vaccine regimen all showed a median inhibition percentage of no more than 30%. This supports a previous study showing the estimated effectiveness of two doses of a COVID-19 vaccine was high against symptomatic Delta infection while it was lower against symptomatic Omicron infection.21
Although mRNA vaccines seem to stimulate the highest response for the Delta variant, RTX and AZA showed a significant attenuation of the inhibition percentages to the Delta variant compared to the no IMT group.
The T cell response showed no significant difference among vaccine platforms after the second or third dose vaccination or among the groups treated with RTX, non-anti-CD20 therapy, and no IMTs.
These findings support the evidence that anti-CD20 therapy, such as RTX, attenuates vaccine responsiveness due to B lymphocyte suppression, concordant with previous
reports.10,11 A cohort study10 showed patients with chronic inflammatory disease receiving B cell depletion therapy would have lower humoral responsiveness measured by spike IgG, NAb, and circulating S-specific plasmablast after COVID vaccination. Some studies22,23 measured antibody response for the mRNA vaccine regimens in neurological patients, showing similar results. FGM and anti-CD20 therapy, such as RTX, showed no detectable immune response to the COVID-19 vaccines. Based on the drug mechanism, RTX can mediate B cell depletion by binding to the CD20 receptor on the B cell surface, resulting in eliciting fewer B cells immune responses.24 FGM might play a role in inhibiting germinal center formation, resulting in fewer immune responses and less recall of antigens.25 Theoretically, anti-CD-20 depleting agents, such as ocrelizumab and RTX, might cause a lower protective response to COVID-19 vaccines.26 Nevertheless, several studies showed anti-CD20 treatments decreased the humoral response, but did not interfere with the cellular response.27,28 B cell immunity and T cell response are essential for fighting COVID-19 infection, and the T cell level is accepted to be one of the predictors of COVID-19 severity.29 We only evaluated one modality of B-cell function, which was the antibody response as levels of anti-RBD and NAbs.30,31 The NAb assay in the present study is a surrogate neutralizing antibody assay (sVNT), which is a blocking ELISA detection kit that detects the presence of neutralizing antibodies against SARS-CoV-2 RBD.32,33 However, NAbs do not necessarily correlate with anti-RBD activity. It should also be noted that immunoglobulin classes other than IgG could be important, especially in patients who received anti-CD20 therapy.
This prospective observational study had several limitations. The sample sizes in the compared groups were small, so comparisons may have been underpowered to detect true differences. Since our study is a real-life practice amongst consecutive cases, we could not test all the patients on all three tests, immunoglobulin classes, and adverse events of each patient due to time and resource limitations and the lack of correlation with clinical outcomes.
In conclusion, we have investigated the immunity response to COVID-19 vaccination in Thai patients with autoimmune neurological disease. In general, all DMDs/ ISs may slightly decrease antibody level response, but they may not decrease cellular immunity. This cellular immunity may be sufficient to reduce the severity of COVID-19 infection. However, in MS patients on RTX or FGM therapy, choosing an mRNA vaccine regimen might be desirable (if possible) because of its superior
immunogenicity evidenced by a higher B cell response. To date, there has been no consensus on suggestions or recommendations for specific COVID vaccine platforms for patients with autoimmune neurological disease. Therefore, generalizing the results of the present study to other diseases and geographic areas requires caution.
ACKNOWLEDGMENTS
We would like to thank Khemjira Karaketklang for data analysis.
None.
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
The research project was funded by the Faculty of Medicine, Siriraj Hospital, with the funding code R016533016.
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