key: cord-0907233-bryqfmes authors: Nanthapisal, S.; Puthanakit, T.; Jaru-Ampornpan, P.; Nantanee, R.; Sodsai, P.; Himananto, O.; Sophonphan, J.; Suchartlikitwong, P.; Hiransuthikul, N.; Angkasekwinai, P.; Tangsathapornpong, A.; Hirankarn, N. title: A randomized clinical trial of a booster dose with low versus standard dose of AZD1222 in adult after 2 doses of inactivated vaccines date: 2022-02-15 journal: nan DOI: 10.1101/2022.02.15.22270974 sha: 883ab493e55da91b90ec7db02c77ded9ae27f2db doc_id: 907233 cord_uid: bryqfmes Background: Immunogenicity of inactivated SARS-CoV-2 vaccine has waning antibody over time. With the emergence of the SARS-CoV-2 delta variant, which requires higher neutralizing antibody to prevent infection, a booster dose is needed. Objective: To evaluate immunogenicity and reactogenicity of standard- versus low-dose ChAdOx1 nCoV-19 vaccine booster after CoronaVac in healthy adults. Methods: A double-blinded, randomized, controlled trial of adult, aged 18-59 years, with completion of 2-dose CoronaVac at 21-28 days apart for more than 2 months was conducted. Participants were randomized to receive AZD1222 (Oxford/AstraZeneca) intramuscularly; standard dose (SD, 5x1010 viral particles) or low dose (LD, 2.5x1010 viral particles). Surrogate virus neutralization test (sVNT) against wild type and delta variant, and anti-spike-receptor-binding-domain IgG (anti-S-RBD IgG) were compared as geometric mean ratio (GMR) at day 14 and 90 between LD and SD arms. Results: From July-August 2021, 422 adults with median age of 44 (IQR 36-51) years were enrolled. The median interval from CoronaVac to AZD1222 booster was 77 (IQR 64-95) days. At baseline, geometric means (GMs) of sVNT against delta variant and anti-S-RBD IgG were 18.1%inhibition (95%CI 16.4-20.0) and 111.5 (105.1-118.3) BAU/ml. GMs of sVNT against delta variant and anti-S-RBD IgG in SD were 95.6%inhibition (95%CI 94.3-97.0) and 1975.1 (1841.7-2118.2) BAU/ml at day 14, and 89.4%inhibition (86.4-92.4) and 938.6 (859.9-1024.4) BAU/ml at day 90, respectively. GMRs of sVNT against delta variant and anti-S-RBD IgG in LD compared to SD were 1.00 (95%CI 0.98-1.02) and 0.84 (0.76-0.93) at day 14, and 0.98 (0.94-1.03) and 0.89 (0.79-1.00) at day 90, respectively. LD recipients had significantly lower rate of fever (6.8%vs25.0%) and myalgia (51.9%vs70.7%) compared to SD. Conclusion: Half-dose AZD1222 booster after 2-dose inactivated SARS-CoV-2 vaccination had non-inferior immunogenicity, yet lower systemic reactogenicity. Fractional low-dose AZD1222 booster should be considered especially in resource-constrained settings. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.15.22270974 doi: medRxiv preprint 1. Introduction 6 months after mRNA-1273 primary vaccination series [11] . 135 Heterologous prime-boost vaccinations, the sequential administration of vaccines 136 using different antigen delivery systems [12] , have been reported as a good strategy to 137 enhance cellular immune response against various viral pathogens including SARS-CoV-2 138 [13] . Studies on heterologous prime-boost vaccinations against SARS-CoV-2, using lipid 139 nanoparticle-formulated mRNA vaccine BNT162b2 (BioNTech/Pfizer) as a booster dose in 140 AZD1222-primed participants, showed significantly higher frequencies of spike-specific 141 CD4+ and CD8+ T cells than participants who received two-dose AZD1222 [14] . In 142 CoronaVac followed by AZD1222 vaccinees, the geometric mean of spike receptor binding 143 domain (S-RBD) IgG titers were higher than 2-dose AZD1222 vaccinees, with the level of 144 1492 BAU/ml and 178 BAU/ml, respectively . Moreover, a recent study from Thailand 145 [16] showed that standard and half dose of BNT162b2 boosters after 2-dose inactivated 146 vaccine series increased both antibody and cellular immune response against SARS-CoV-2. 147 The objective of this study was to determine antibody response, cellular response, and 148 reactogenicity of standard versus low dose AZD1222 as a booster dose after completion of 2-149 dose CoronaVac in healthy adult. 150 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.15.22270974 doi: medRxiv preprint All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Thammasat University, Pathum Thani, and Chulalongkorn University Health Center, Faculty 155 of Medicine, Chulalongkorn University, Bangkok, Thailand. This is a double-blinded, 156 randomized, controlled trial. Healthy adult, age 18 -59 years old, who completed two doses 157 of CoronaVac for more than 60 days, with interval of 21 -28 days were included in this 158 study. Participants who received any immunosuppressants or blood products within 3 months 159 or any vaccines within 2 weeks before study enrollment were excluded. All The participants were stratified into two age strata, age 18 -45 years and 46 -59 168 years. The randomization process was performed using a block of two or four in sealed 169 envelope. The participants were vaccinated in participant-blinded fashion, with intramuscular 170 AZD1222 lot number A1009 and A10061, manufactured by Siam Bioscience Co., Ltd., 0.25 171 ml (2.5 x 10 10 viral particles, low dose [LD]) or 0.5 ml (5 x 10 10 viral particles, standard dose 172 [SD]). The vaccination was performed by unblinded nurses. Therefore, the participants and 173 blinded study team were not aware of the randomization arms. During the first 7 days after 174 vaccination, participants recorded the solicited local and systemic reactogenicity in the diary. 175 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. were pre-stimulated with R848 and IL-2 for 72 hours to allow memory B cells to differentiate 215 into antibody-secreting cells. Unstimulated well was also used as negative control. An RBD-216 WASP antigen was added into RBD-specific IgG detected well while MT78/145-217 biotinylated antibodies were added into total IgG detected well. Anti-WASP-ALP and 218 streptavidin-ALP were added into RBD-specific IgG detected well and total IgG detected 219 well, respectively. 220 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. symptoms; grade 1 for mild symptom, which was not interfere with activities or vomiting 1 -229 2 times/day or diarrhea 2 -3 times/day; grade 2 for moderate symptom, which interfered with 230 activities or needed medication for symptom relief, or vomiting more than 2 times/day or 231 diarrhea 4 -5 times/day; grade 3 for severe symptom, which incapacitated or diarrhea 6 or 232 more times/day; grade 4 for potentially life-threatening symptom which required emergency 233 room visit or hospitalization. Fever was graded as grade 1 (38.0 -38.4 o C), grade 2 (38.5 -234 38.9 o C), grade 3 (39 -40 o C), and grade 4 (more than 40 o C). Feverish was defined as feeling 235 of fever but body temperature less than 38.0 o C. Unsolicited adverse events were also 236 recorded by study team at all visits. 237 The sample size was calculated using a non-inferiority criterion for the geometric 239 mean ratio (GMR) of sVNT against wild type and delta variant, and anti-S-RBD IgG, 240 comparing LD to SD. Assuming All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The reactogenicity rates were compared using chi-square test. All reported p-values are two-257 sided. P values <0.05 were considered to be statistically significant. Statistical analysis was 258 performed using Stata version Correlation between the levels of anti-S-RBD IgG and receptor-blocking antibodies as 260 measured by sVNT was analyzed for both wild type and delta strains by non-linear regression 261 fit in GraphPad Prism 9 (GraphPad software, San Diego, CA). Data from the sub-population 262 with anti-S-RBD IgG titer below 1200 BAU/mL were used in the correlation analysis. 263 264 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. From July to August 2021, 422 adults with median age of 44 (IQR 36 -51) years 267 participated. The trial profiles and demographic data are shown in Figure 1 and Table 1 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The levels of antibodies capable of inhibiting binding between hACE2 receptor and S-318 RBD from both Wuhan and Delta strains were well-correlated with the levels of anti-RBD 319 IgG (R 2 = 0.80 for wild type and R 2 = 0.84 for delta strain). Correlation analyses between 320 anti-S-RBD IgG and sVNT from participants with anti-S-RBD less than 1200 BAU/ml at any 321 time points were shown in Figure 4 . Only 8.1% of participants with anti-RBD IgG levels 322 higher than 1200 BAU/mL achieved lower than 95% inhibition levels in both sVNT assays. 323 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The median frequencies of T cell response to SNMO peptides and RBD-specific B 335 cells with SARS-CoV-2 at baseline, and day 28 and day90 after booster dose are shown in 336 The median frequencies of RBD-specific B cells were very low at baseline; 1 (IQR 0 -16) 341 cells/10 6 PBMCs in LD and 0 (0 -6.5) cells/10 6 PBMCs in SD at day 0 and raised to 18 (8 -342 42) and 26 (4 -54) cells/10 6 PBMCs at day 28 in LD and SD group, respectively. Both T and 343 B cell responses were comparable between LD and SD group. 344 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The fractional low-dose concept of SARS-CoV-2 vaccine has been investigated. A 360 quarter dose of mRNA-1273 was able to generate T cell responses, both spike-specific 361 memory CD4+ T cells and spike-specific CD8+ T cells, in almost all of the participants at 6 362 months after 2 doses, which were comparable in quantity and quality to COVID-19 cases 363 [10]. In the view of immunological memory, lower antigen level could activate quicker and 364 stronger secondary immune response to previously encountered antigen [23]. Therefore, low-365 dose vaccination could be an effective booster. 366 Feng et al. [18] reported that the anti-S-RBD IgG level associated with 80% vaccine 367 efficacy against symptomatic COVID-19 was 506 BAU/ml. For sVNT, 68% inhibition might 368 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The strengths of this study were the double-blinded, randomized, controlled study 385 design, and multiple methods of immunologic assessments, both humoral and cellular 386 immunity, to wild type and variants of concern. We reported anti-S-RBD IgG and sVNT, 387 especially to delta variant which was the major cause of outbreak in many countries, 388 including Thailand. The limitation included the interval from last vaccination was only 2-3 389 months after completion of 2-dose CoronaVac. Though in the real world, the booster might 390 be given at longer interval from last CoronaVac, in which we expected to have at least similar 391 or even higher immunogenicity. Secondly, this study included healthy adults, and have no 392 data among high-risk groups, such as the elderly or the immunocompromised patients. 393 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Thirdly, the follow up of the participants are ongoing to observe the kinetic of antibody 394 decline and risk of breakthrough infection if any occurred. Lastly, this study did not perform 395 sVNT for recently emerged variants e.g., Omicron, however, the comparable T cell responses 396 between standard and low dose AZD1222 booster could likely prevent severe symptoms of 397 COVID-19 caused by these variants. 398 399 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The authors declare that they have no known competing financial interests or personal 432 relationships that could have appeared to influence the work reported in this paper. 433 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The systemic reactions that are significant lower in the AZD1222 booster lower dose arm include: fever and feverish (p<0.001), headache (p<0.007), fatigue (p =0.01) and myalgia (p<0.001). All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Table 2 . Results of sVNT to delta variant, sVNT to wild type, and anti-S-RBD IgG at day 14 and day 90, and non-inferior comparison between low dose and standard dose AZD1222 booster in adult after 2 doses of inactivated vaccines. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. • Grade 3 28 (6.8) 10 (4.9) 18 (8.7) Swelling 10 (2.4) 4 (1.9) 6 (2.9) 0.53 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.15.22270974 doi: medRxiv preprint Immune responses against SARS-CoV-2 variants after heterologous and 479 homologous ChAdOx1 nCoV-19/BNT162b2 vaccination Immunogenicity of a third dose viral-vectored COVID-19 vaccine after 483 receiving two-dose inactivated vaccines in healthy adults Immunogenicity and Safety of an Intradermal BNT162b2 mRNA Vaccine Booster after Two Doses of Inactivated SARS-CoV-2 Vaccine in Healthy Population A serological assay to detect SARS-CoV-2 seroconversion in humans Correlates of protection 494 against symptomatic and asymptomatic SARS-CoV-2 infection A SARS-CoV-2 surrogate virus 497 neutralization test based on antibody-mediated blockage of ACE2-spike protein-protein 498 interaction