# Assessment of 4 Doses of SARS-CoV-2 Messenger RNA-Based Vaccine in Recipients of a Solid Organ Transplant

Nassim Kamar, Florence Abravanel, Olivier Marion, Raphaelle

Romieu-Mourez, Chloé Couat, Arnaud del Bello, Jacques Izopet

► To cite this version:

Nassim Kamar, Florence Abravanel, Olivier Marion, Raphaelle Romieu-Mourez, Chloé Couat, et al. Assessment of 4 Doses of SARS-CoV-2 Messenger RNA-Based Vaccine in Recipients of a Solid Organ Transplant. JAMA Network Open, 2021, 4 (11), pp.e2136030. 10.1001/jamanet-workopen.2021.36030. hal-03771240

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**Research Letter** | Infectious Diseases

# Assessment of 4 Doses of SARS-CoV-2 Messenger RNA-Based Vaccine in Recipients of a Solid Organ Transplant

Nassim Kamar, MD, PhD; Florence Abravanel, PharmD, PhD; Olivier Marion, MD; Raphaelle Romieu-Mourez, MSc; Chloé Couat, MSc; Arnaud Del Bello, MD; Jacques Izopet, PharmD, PhD

## Introduction

Anti-SARS-CoV-2 antibodies have been detected in up to approximately 70% of solid organ transplant recipients who were given 3 doses of the SARS-CoV-2 vaccine.¹,² In France, it has been allowed to offer a fourth dose on a case-by-case basis.³ We assessed whether a fourth dose of the SARS-CoV-2 vaccine is associated with improved anti-SARS-CoV-2 antibody concentrations in solid organ transplant recipients in France.

## + Supplemental content

Author affiliations and article information are listed at the end of this article.

## Methods

This case series study was conducted from July 1, 2021, to August 5, 2021. A fourth dose of the messenger RNA-based BNT162b2 vaccine (Pfizer-BioNTech) was given to the 37 solid organ transplant recipients, including 5 (13.5%) who had a weak response to the previous 3 doses (antibody concentration <14 binding antibody units [BAU]/mL)⁴ and 31 (83.8%) who had no response to the 3 previous doses. All participants provided oral informed consent and received approval of the medical staff (Table). According to French law (Loi Jardé), anonymous retrospective studies do not require institutional review board approval. This study followed the reporting guideline for case series.

The first 2 doses were given 1 month apart, the third dose was administered a mean (SD) of 57 (17) days after the second dose, and the last dose was given a mean (SD) of 65 (9) days after the third dose. Anti-SARS-CoV-2 spike protein total antibody concentrations were assessed using the Wantai enzyme-linked immunosorbent assay test. Neutralizing antibody (NAb) titers were assessed using a live virus neutralization assay. Enzyme-linked immunospot assay measuring interferon (IFN)-γ produced by specific SARS-CoV-2 T cells was performed for 14 patients (eMethods in the Supplement). Proportions were compared using the Fisher exact test. Quantitative variables were compared by the Student t test or the Mann-Whitney test. A 2-sided *P* value <.05 was considered to be statistically significant. All statistical analyses were performed with Prism Software v8.1 (GraphPad).

## Results

Of 37 patients included in this case series study, 20 (54.0%) were male, with a mean (SEM) age of 60 (14) years. Anti-SARS-CoV-2 antibodies were detected in 5 of 37 patients (13.5%) before dose 4 and in 18 of 37 patients (48.6%) 1 month later (*P* = .002). Among the 5 patients who were seropositive before dose 4, the median antibody concentration increased from 4 BAU/mL (range, 1-9 BAU/mL) to 402 BAU/mL (range, 87-508 BAU/mL) at 4 weeks after dose 4 (*P* < .001) (Figure, A). Neutralizing antibody titers increased from a median of 8 IU/mL (range, 2-32 IU/mL) to 16 IU/mL (range, 4-32 IU/mL) (*P* = .07).

Among the 31 patients who were seronegative before dose 4, 13 (41.9%) became seropositive (median antibody concentration, 9.5 BAU/mL [range, 1.7-658 BAU/mL]) at 4 weeks after dose 4; 6 patients (19.4%) had antibody concentrations greater than 14 BAU/mL, and 2 (6.5%) had antibody

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Open Access. This is an open access article distributed under the terms of the CC-BY License.
concentrations greater than 140 BAU/mL (Figure, A). Among these patients, the median NAb titer was 8 IU/mL (range, 2-32 IU/mL).

At 4 weeks after dose 4, antibody concentrations were significantly higher among patients who had detectable antibodies before dose 4 than among those who had no response. However, Nab titers at 4 weeks after dose 4 did not differ between responders and nonresponders to 3 doses.

Overall, at 4 weeks after dose 4, 32 of 37 patients (86.5%) had antibody concentrations less than 140 BAU/mL (a threshold providing 12.4% protection among health care workers⁴) and all 37 patients (100%) had NAb titers less than 64 IU/mL. No breakthrough infection was observed during follow-up.

<table><caption>Table. Clinical and Biological Characteristics of Solid Organ Transplant Recipients According to Humoral Response 1 Month After 3 Doses of mRNA-Based Vaccine</caption><thead><tr><th rowspan="2">Characteristic</th><th rowspan="2">All patients<br>(N = 37)</th><th colspan="2">Patients seronegative before dose 4<sup>a</sup></th><th rowspan="2">P value</th></tr><tr><th>Remained<br>seronegative<br>(n = 19)</th><th>Became<br>seropositive<br>(n = 13)</th></tr></thead><tbody><tr><td>Gender, No. (%)</td><td></td><td></td><td></td><td></td></tr><tr><td>Male</td><td>20 (54.0)</td><td>12 (63.2)</td><td>6 (46.2)</td><td rowspan="2">.26</td></tr><tr><td>Female</td><td>17 (46.0)</td><td>5 (26.3)</td><td>7 (53.8)</td></tr><tr><td>Age, mean (SEM), y</td><td>60 (14)</td><td>58 (16)</td><td>60 (14)</td><td>.76</td></tr><tr><td>Type of organ transplant, No. (%)</td><td></td><td></td><td></td><td></td></tr><tr><td>Kidney</td><td>25 (67.6)</td><td>11 (57.9)</td><td>13 (100)</td><td rowspan="4">.03</td></tr><tr><td>Heart</td><td>5 (13.5)</td><td>4 (21.1)</td><td>0</td></tr><tr><td>Liver</td><td>4 (10.8)</td><td>4 (21.1)</td><td>0</td></tr><tr><td>Pancreas</td><td>3 (8.1)</td><td>0</td><td>0</td></tr><tr><td>Rejection in the year before vaccination, No.</td><td>0</td><td>0</td><td>0</td><td>NA</td></tr><tr><td>Time between vaccine and transplant, mean (SD), mo</td><td>109 (84)</td><td>79 (66)</td><td>161 (97)</td><td>.007</td></tr><tr><td>Induction therapy, No. (%)</td><td></td><td></td><td></td><td></td></tr><tr><td>No</td><td>12 (32.4)</td><td>9 (47.4)</td><td>2 (15.4)</td><td>.12</td></tr><tr><td>Yes</td><td>25 (67.6)</td><td>10 (52.6)</td><td>11 (84.6)</td><td>.12</td></tr><tr><td>Anti-IL-2 receptor blockers</td><td>15 (60.0)</td><td>6 (60.0)</td><td>6 (54.5)</td><td>.99</td></tr><tr><td>Polyclonal antibodies</td><td>10 (40.0)</td><td>4 (40.0)</td><td>5 (45.5)</td><td>.99</td></tr><tr><td>Type of immunosuppressive regimen, No. (%)</td><td></td><td></td><td></td><td></td></tr><tr><td>Calcineurin-inhibitors</td><td>32 (86.5)</td><td>17 (89.5)</td><td>10 (76.9)</td><td>.37</td></tr><tr><td>Tacrolimus</td><td>30 (93.8)</td><td>17 (100)</td><td>8 (80.0)</td><td>.13</td></tr><tr><td>Ciclosporin A</td><td>2 (6.3)</td><td>0 (0)</td><td>2 (20.0)</td><td>.13</td></tr><tr><td>Mycophenolic acid</td><td>32 (86.5)</td><td>15 (78.9)</td><td>12 (92.3)</td><td>.62</td></tr><tr><td>mTOR inhibitors</td><td>9 (24.3)</td><td>4 (21.1)</td><td>4 (30.8)</td><td>.68</td></tr><tr><td>Steroids</td><td>34 (91.9)</td><td>17 (89.5)</td><td>12 (92.3)</td><td>.99</td></tr><tr><td>Count before vaccination, mean (SD), per mm<sup>3</sup></td><td></td><td></td><td></td><td></td></tr><tr><td>Neutrophils</td><td>6413 (1892)</td><td>6763 (2255)</td><td>5714 (1402)</td><td>.14</td></tr><tr><td>Lymphocytes</td><td>1298 (742)</td><td>1126 (527)</td><td>1609 (906)</td><td>.07</td></tr><tr><td>CD4<sup>+</sup> T cells</td><td>370 (211)<sup>b</sup></td><td>351 (197)<sup>c</sup></td><td>374 (144)<sup>d</sup></td><td>.45</td></tr><tr><td>CD8<sup>+</sup> T cells</td><td>393 (261)<sup>b</sup></td><td>452 (271)<sup>c</sup></td><td>342 (201)<sup>d</sup></td><td>.23</td></tr><tr><td>CD19<sup>+</sup> T cells</td><td>61 (59)<sup>b</sup></td><td>74 (71)<sup>c</sup></td><td>59 (44)<sup>d</sup></td><td>.88</td></tr><tr><td>NK cells</td><td>202 (115)<sup>b</sup></td><td>228 (133)<sup>c</sup></td><td>126 (52)<sup>d</sup></td><td>.11</td></tr><tr><td>eGFR before vaccination, mean (SD), mL/min/1.73 m<sup>2</sup></td><td>45 (21)</td><td>42 (20)</td><td>45 (22)</td><td>.71</td></tr><tr><td>Neutrophil count before dose 4, mean (SD), per mm<sup>3</sup></td><td>5357 (2070)</td><td>5647 (2227)</td><td>6046 (1438)</td><td>.57</td></tr><tr><td>Lymphocyte count before dose 4, mean (SD), per mm<sup>3</sup></td><td>1193 (711)</td><td>947 (427)</td><td>1431 (866)</td><td>.04</td></tr><tr><td>eGFR before dose 4, mean (SD), mL/min/1.73 m<sup>2</sup></td><td>45 (20)</td><td>43 (19)</td><td>45 (23)</td><td>.81</td></tr></tbody></table>

Abbreviations: eGFR, estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration equation); IL-2, interleukin-2; mTOR, mammalian target of rapamycin; NA, not applicable; NK, natural killer.

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<footnote>a Comparison between patients who were seronegative before the fourth dose and who either remained seronegative or became seropositive after the fourth dose.</footnote>

<footnote>b Data are for 26 patients.</footnote>

<footnote>c Data are for 14 patients.</footnote>

<footnote>d Data are for 7 patients.</footnote>
<figure><img src="image_5.png" /><figcaption>Figure. Anti-SARS-CoV-2 Antibody Concentrations and Number of SARS-CoV-2-Reactive IFN-γ-Producing Cells After a Fourth Dose of the SARS-CoV-2 Messenger RNA (mRNA) BNT162b2 Vaccine</figcaption></figure>

A, The dotted line represents the cutoff value. B, The numbers of cells reactive to overlapping peptide pools spanning SARS-CoV-2 structural protein S (pools S1 and S2) are shown. The numbers of SARS-CoV-2-reactive IFN-γ-producing cells in the 3 patients who had a low antibody concentration before the fourth dose were 17.5, 47.5, and 110 spot-forming units (SFUs) per 10⁶ peripheral blood mononuclear cells (PBMCs). BAU indicates binding antibody unit.

At 4 weeks after D4, the number of SARS-CoV-2-reactive IFN-γ-producing cells was 61.25 spot-forming units (SFUs) per 10⁶ peripheral blood mononuclear cells (PBMCs) (range, 2.5-372.5 SFUs per 10⁶ PBMCs), with 167.5 SFUs per 10⁶ PBMCs (range, 47.5-372.5 SFUs per 10⁶ PBMCs) among seropositive patients and 55 SFU per 10⁶ PBMC (range, 2.5-110 SFUs per 10⁶ PBMC) among seronegative patients (Figure, B).

No serious adverse event or acute rejection was observed after dose 4. One kidney transplant recipient presented with a recurrence of IgA nephropathy. Four patients presented with fatigue and myalgia. One patient indicated gastrointestinal symptoms.

Discussion

In this case series study, our findings were similar to those of the study by Alejo et al,⁵ in which a fourth dose of SARS-CoV-2 vaccine was associated with slightly improved humoral response among patients with a weak response after 3 doses and with no improvement among those with no response after 3 doses. Neutralizing antibody titers and cellular response were low in both groups. In a study⁶ of 22 healthy volunteers (median age, 59 years), among all individuals, antibody concentrations at 1 month after 2 doses of BNT162b2 vaccine were greater than 140 BAU/mL (median, 1309 BAU/mL [range, 457-7605 BAU/mL]) and NAb titers were greater than 64 IU/mL (median 128 [range, 64-512 IU/mL]). In another study of 20 healthy volunteers (median age, 55 years), the number of SARS-CoV-2-reactive IFN-γ-producing cells at 1 month after 2 doses of BNT162b2 vaccine was 542 SFUs per 10⁶ PBMCs (range, 0-1669 SFUs per 10⁶ PBMCs) (Jacques Izopet, Pharm D, PhD, unpublished data). A limitation of our study was the small number of patients. Other strategies should be tested for solid organ transplant recipients.

ARTICLE INFORMATION

Accepted for Publication: September 28, 2021.

**Published:** November 24, 2021. doi:10.1001/jamanetworkopen.2021.36030

**Open Access:** This is an open access article distributed under the terms of the **CC-BY License**. © 2021 Kamar N et al. *JAMA Network Open*.

**Corresponding Author:** Nassim Kamar, MD, PhD, Department of Nephrology and Organ Transplantation, Toulouse University Hospital, TSA 50032, 31059 Toulouse Cedex 9, France (kamar.n@chu-toulouse.fr).

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**Author Affiliations:** Department of Nephrology and Organ Transplantation, Toulouse University Hospital, Toulouse, France (Kamar, Marion, Couat, Del Bello); Université Paul Sabatier, Toulouse, France (Kamar, Abravanel, Marion, Izopet); Toulouse Institute for Inflammatory and Infectious Diseases (Infinity), Inserm, French National Centre for Scientific Research, Toulouse, France (Kamar, Abravanel, Marion, Del Bello, Izopet); Department of Virology, Toulouse University Hospital, Toulouse, France (Abravanel, Romieu-Mourez, Izopet).

**Author Contributions:** Dr Kamar had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

**Concept and design:** Kamar, Marion, Del Bello.

**Acquisition, analysis, or interpretation of data:** Kamar, Abravanel, Marion, Romieu-Mourez, Couat, Izopet.

**Drafting of the manuscript:** Kamar.

**Critical revision of the manuscript for important intellectual content:** Kamar, Abravanel, Marion, Couat, Del Bello, Izopet.

**Statistical analysis:** Kamar, Couat.

**Administrative, technical, or material support:** Abravanel, Romieu-Mourez, Couat.

**Supervision:** Abravanel, Del Bello, Izopet.

**Conflict of Interest Disclosures:** Dr Kamar reported receiving speaker fees and participating in advisory boards for AbbVie, Astellas, Biotest, CSL Behring, Chiesi, Merck Sharp and Dohme, Neovii, Novartis Pharma, Sanofi, Sandoz, Shire, and Takeda and receiving personal fees from AbbVie, Astellas, Biotest, CSL Behring, Chiesi, Merck Sharp and Dohme, Neovii, Novartis Pharma, Sanofi, Sandoz, Shire, and Takeda outside the submitted work. No other disclosures were reported.

## REFERENCES

1. Kamar N, Abravanel F, Marion O, Couat C, Izopet J, Del Bello A. Three doses of an mRNA Covid-19 vaccine in solid-organ transplant recipients. *N Engl J Med*. 2021;385(7):661-662. doi:10.1056/NEJMc2108861

2. Hall VG, Ferreira VH, Ku T, et al. Randomized trial of a third dose of mRNA-1273 vaccine in transplant recipients. *N Engl J Med*. 2021;385(13):1244-1246. doi:10.1056/NEJMc2111462

3. La Société Francophone de Transplantation. Renaloo. Accessed July 21, 2021. https://renaloo.com/wp-content/uploads/2021/07/20210717-mailing-SFT-4edose.pdf

4. Dimeglio C, Herin F, Martin-Blondel G, Miedougé M, Izopet J. Antibody titers and protection against a SARS-CoV-2 infection. *J Infect*. Published online September 20, 2021. doi:10.1016/j.jinf.2021.09.013

5. Alejo JL, Mitchell J, Chiang TP, et al. Antibody response to a fourth dose of a SARS-CoV-2 vaccine in solid organ transplant recipients: a case series. *Transplantation*. 2021. doi:10.1097/TP.00000000000003934

6. Dimeglio C, Herin F, Da-Silva I, et al. Heterologous ChAdOx1-S/BNT162b2 vaccination: neutralizing antibody response to SARS-CoV-2. *Clin Infect Dis*. Published online August 12, 2021. doi:10.1093/cid/ciab705

## SUPPLEMENT

### eMethods.

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