ABSTRACT
BackgroundEffective COVID-19 mRNA vaccines are mainly available in high-income countries. ChulaCov19, a prefusion non-stabilized Spike protein-encoding, nucleoside-modified mRNA, lipid nanoparticle encapsulated vaccine development, aims to enhance accessibility of mRNA vaccine and future pandemic preparedness for low- to middle-income countries. MethodsSeventy-two eligible volunteers, 36 aged 18-55 (adults) followed by 36 aged 56-75 (elderly) enrolled in a dose escalation study of ChulaCov19 mRNA vaccine. Two doses of vaccine were given 21 days apart at 10, 25, or 50 {micro}g/dose (12/group). Safety was the primary and immunogenicity the secondary outcome. Human convalescents (HCS) and Pfizer/BioNTech vaccinees sera provided comparison panels. ResultsAll three doses of ChulaCov19 were well tolerated and elicited robust dose-dependent and age- dependent B- and T-cell responses. Transient mild/moderate injection site pain, fever, chills, fatigue, and headache were more common after the second dose. Four weeks after the second ChulaCov19: dose at 10, 25, and 50 {micro}g dose, MicroVNT-50 Geometric mean titer (GMT) against wild-type was 848, 736 and 1,140 IU/mL, respectively, versus 267 IU/mL for HCS. All dose levels elicited 100% seroconversion, with GMT ratio 4-8-fold higher than for HCS (p<0.01), and high IFN{gamma} spot-forming cells/million peripheral blood mononuclear cells. The 50 {micro}g dose induced better cross-neutralization against Alpha, Beta, Gamma, and Delta variants than lower doses. ConclusionsChulaCov19 at 50 {micro}g/dose is well tolerated and elicited higher neutralizing antibodies than HCS with strong T-cell responses. These antibodies cross neutralized four variants of concern and ChulaCov19 has therefore proceeded to phase 2 and 3 clinical trials. Trial registration numberClinicalTrials.gov Identifier NCT04566276 Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/22274989v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@3f6e6corg.highwire.dtl.DTLVardef@6aa1b7org.highwire.dtl.DTLVardef@9f0c29org.highwire.dtl.DTLVardef@1d75e38_HPS_FORMAT_FIGEXP M_FIG C_FIG
ABSTRACT
BackgroundImmunogenicity 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. ObjectiveTo evaluate immunogenicity and reactogenicity of standard- versus low-dose ChAdOx1 nCoV-19 vaccine booster after CoronaVac in healthy adults. MethodsA 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. ResultsFrom 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. ConclusionHalf-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. Highlights- Low dose AZD1222 could boost comparable immunity to standard dose in healthy adult who completed 2 doses of inactivated SARS-CoV-2 vaccines. - Less reactogenicity occurred in low-dose AZD1222 booster than standard-dose recipients. Thai Clinical Trials Registry (thaiclinicaltrials.org): TCTR20210722003
ABSTRACT
BackgroundCurrently, booster dose is needed after 2 doses of inactivated COVID-19 vaccine. With limited resource and shortage of COVID-19 vaccine, intradermal(ID) administration might be a potential dose-sparing strategy. ObjectiveTo determine antibody response and reactogenicity of ID ChAdOx1 nCoV-19 vaccine(AZD1222,Oxford/AstraZeneca) as a booster dose after completion of 2-dose CoronaVac(SV) in healthy adult. MethodsThis is a prospective cohort study of adult aged 18-59 years who received 2-dose SV at 14-35 days apart for more than 2 months. Participants received ID AZD1222 at fractional low dose(1x1010 viral particles,0.1ml). Antibody responses were evaluated by surrogate virus neutralization test(sVNT) against wild type and delta variant and anti-spike-receptor-binding-domain immunoglobulin G(anti-S-RBD IgG) at prior, day14 or 28, and day90 post booster. Solicited reactogenicity was collected during 7 days post-booster. Primary endpoint was the differences of sVNT against delta strain [≥]80%inhibition at day14 and 90 compared with the parallel cohort study of 0.5-ml intramuscular(IM) route. ResultsFrom August2021, 100 adults with median(IQR) age of 46(41-52) years participated. At baseline, geometric means(GMs) of sVNT against delta strain prior to booster were 22.4%inhibition(95%CI 18.7-26.9) and of anti-S-RBD IgG were 109.3(95.4-125.1)BAU/ml. GMs of sVNT against delta strain were 92.9%inhibition(95%CI 87.7-98.3) at day14 and 73.1%inhibition(66.7-80.2) at day90 post ID booster. The differences of proportion of participants with sVNT to delta strain[≥]80%inhibition in ID recipients versus IM were +4.2%(95%CI-2.0to10.5) at day14, and -37.3%(-54.2to-20.3) at day90. Anti-S-RBD IgG GMs were 2037.1(95%CI1770.9-2343.2) at day14 and 744.6(650.1-852.9) BAU/ml at day90, respectively. Geometric mean ratios(GMRs) of anti-S-RBD IgG were 0.99(0.83-1.20) at day14, and 0.82(0.66-1.02) at day90. Only 18% reported feverish, compared with 37% of IM(p=0.003). Only 18% reported feverish, compared with 37% of IM(p=0.003). Common reactogenicity was erythema(55%) at injection site while 7% reported blister. ConclusionLow-dose ID AZD1222 booster enhanced lower neutralizing antibodies at 3 months compared with IM route. Less systemic reactogenicity occurred, but higher local reactogenicity. HighlightsO_LIIntradermal AZD1222 booster vaccine gave comparable short-term immunogenicity but lower 90-day immunogenicity with conventional intramuscular vaccine. C_LIO_LILower systemic but higher local reactogenicity was found in intradermal AZD1222 booster vaccine. C_LIO_LIBlister and pruritus could be seen after intradermal AZD1222 booster vaccine. C_LI
ABSTRACT
BackgroundInactivated SARS-CoV-2 (CoronaVac(R),Sinovac, or SV) and ChAdOx1 nCoV-19 (Vaxzevria(R),Oxford-Astra Zeneca, or AZ) vaccines have been administered to the health care workers (HCWs) in Thailand. ObjectiveTo determine the short-term immune response after the SV and AZ vaccinations in HCWs. MethodsIn this prospective cohort study, HCWs who completed a 2-dose regimen of the SV or AZ were included. Immune response was evaluated by surrogate viral neutralization test (sVNT) and anti-SARS-CoV-2 total antibody. Blood samples were analyzed at 4 and 12 weeks after the complete SV vaccination and at 4 weeks after each dose of the AZ vaccination. The primary outcome was the seroconversion rate at 4-weeks after complete immunization. ResultsOverall, 185 HCWs with a median (IQR) age of 40.5(30.3-55.8) years (94 HCWs in the SV group and 91 in the AZ group) were included. At 4 weeks after completing the SV vaccination, 60.6% (95%CI:50.0-70.6%) had seroconversion evaluated by sVNT([≥]68%inhibition), comparable to the patients recovered from mild COVID-19 infection(69.0%), with a rapid reduction to 12.2%(95%CI:6.3-20.8) at 12 weeks. In contrast, 85.7%(95%CI:76.8-92.2%) HCWs who completed the second dose of the AZ for 4 weeks had seroconversion, comparable to the COVID-19 pneumonia patients(92.5%). When using the anti-SAR-CoV-2 total antibody level([≥]132 U/ml) criteria, only 71.3% HCWs in the SV group had seroconversion, compared to 100% in the AZ group. ConclusionA rapid decline of short-term immune response in the HCWs after the SV vaccination indicates the need for a vaccine booster, particularly during the ongoing spreading of the SAR-CoV-2 variants of concern.