Safety and immunogenicity of heterologous boosting with orally administered aerosolized bivalent adenovirus type-5 vectored COVID-19 vaccine and B.1.1.529 variant adenovirus type-5 vectored COVID-19 vaccine in adults 18 years and older: a randomized, double blinded, parallel controlled trial

Vaccination strategies that can induce a broad spectrum immune response are important to enhance protection against SARS-CoV-2 variants. We conducted a randomized, double-blind and parallel controlled trial to evaluate the safety and immunogenicity of the bivalent (5×1010viral particles) and B.1.1.529 variant (5×1010viral particles) adenovirus type-5 (Ad5) vectored COVID-19 vaccines administrated via inhalation. 451 eligible subjects aged 18 years and older who had been vaccinated with three doses inactivated COVID-19 vaccines were randomly assigned to inhale one dose of either B.1.1.529 variant Ad5 vectored COVID-19 vaccine (Ad5-nCoVO-IH group, N=150), bivalent Ad5 vectored COVID-19 vaccine (Ad5-nCoV/O-IH group, N=151), or Ad5 vectored COVID-19 vaccine (5×1010viral particles; Ad5-nCoV-IH group, N=150). Adverse reactions reported by 37 (24.67%) participants in the Ad5-nCoVO-IH group, 28 (18.54%) in the Ad5-nCoV/O-IH group, and 26 (17.33%) in the Ad5-nCoV-IH group with mainly mild to moderate dry mouth, oropharyngeal pain, headache, myalgia, cough, fever and fatigue. No serious adverse events related to the vaccine were reported. Investigational vaccines were immunogenic, with significant difference in the GMTs of neutralizing antibodies against Omicron BA.1 between Ad5-nCoV/O-IH (43.70) and Ad5-nCoV-IH (29.25) at 28 days after vaccination (P=0.0238). The seroconversion rates of neutralizing antibodies against BA.1 in Ad5-nCoVO-IH, Ad5-nCoV/O-IH, and Ad5-nCoV-IH groups were 56.00%, 59.60% and 48.67% with no significant difference among the groups. Overall, the investigational vaccines were demonstrated to be safe and well tolerated in adults, and was highly effective in inducing mucosal immunities in addition to humoral and cellular immune responses defending against SARS-CoV-2 variants.Trial registration: Chictr.org identifier: ChiCTR2200063996.

Safety, immunogenicity and protection of heterologous boost with an aerosolised Ad5-nCoV after two-dose inactivated COVID-19 vaccines in adults: a multicentre, open-label phase 3 trial

BACKGROUND

Aerosolised Ad5-nCoV is one of the first licensed mucosal respiratory vaccine against SARS-CoV-2 in the world; however, the safety profile of this vaccine has not been reported in a large population yet.

METHODS

This multicentre, open-label phase 3 trial, done in 15 centres in six provinces (Jiangsu, Hunan, Anhui, Chongqing, Yunnan, Shandong) in China, aimed to evaluate the safety and immunogenicity of aerosolised Ad5-nCoV in healthy adults (members of the general population with no acute febrile disorders, infectious disease, serious cardiovascular diseases, serious chronic diseases or progressive diseases that cannot be controlled) at least 18 years old, who had received two doses of inactivated COVID-19 vaccine as their primary regimen. This study contained a non-randomly assigned safety cohort and a centrally randomly assigned (1:1) immunogenicity subcohort. The patients in the immunogenicity subcohort received aerosolised Ad5-nCov (aerosolised Ad5-nCoV group) or inactivated vaccine (inactivated COVID-19 group) The primary endpoints were the incidence of adverse reactions within 28 days following the booster vaccination with aerosolised Ad5-nCoV in the safety population (collected through a daily record of any solicited or unsolicited adverse events filled by each participant) and the geometric mean titre of neutralising antibodies at day 28 after the booster dose in the immunogenicity subcohort (measured with a pseudovirus neutralisation test). This study was registered with ClinicalTrials.gov, NCT05204589.

FINDINGS

Between Jan 22, 2022, and March 12, 2022, we recruited 11 410 participants who were screened for eligibility, of whom 10 267 (99·8%) participants (5738 [55·9%] men, 4529 [44·1%] women; median age 53 years [18-92]) received the study drugs: 9847 (95·9%) participants in the open-label cohort to receive aerosolised Ad5-nCoV, and 420 (4·1%) in the immunogenicity subcohort (212 in the aerosolised Ad5-nCoV group and 208 in the inactivated vaccine group). Adverse reactions were reported by 1299 (13%) of 10 059 participants within 28 days after receiving the booster vaccination with aerosolised Ad5-nCoV, but most of the adverse reactions reported were mild to moderate in severity. Participants in the aerosolised Ad5-nCoV group had a significantly higher level of the neutralising antibodies against omicron BA.4/5 (GMT 107·7 [95% CI 88·8-130·7]) than did those in the inactivated vaccine group (17·2 [16·3-18·2]) at day 28.

INTERPRETATION

The heterologous booster regimen with aerosolised Ad5-nCoV is safe and highly immunogenic, boosting both systemic and mucosal immunity against omicron subvariants.

FUNDING

National Natural Science Foundation of China, Jiangsu Provincial Science Fund for Distinguished Young Scholars, and Jiangsu Provincial Key Project of Science and Technology Plan.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Safety, immunogenicity, and efficacy of the mRNA vaccine CS-2034 as a heterologous booster versus homologous booster with BBIBP-CorV in adults aged ≥18 years: a randomised, double-blind, phase 2b trial

BACKGROUND

Heterologous boosting is suggested to be of use in populations who have received inactivated COVID-19 vaccines. We aimed to assess the safety and immunogenicity of a heterologous vaccination with the mRNA vaccine CS-2034 versus the inactivated BBIBP-CorV as a fourth dose, as well as the efficacy against the SARS-CoV-2 omicron (BA.5) variant.

METHODS

This trial contains a randomised, double-blind, parallel-controlled study in healthy participants aged 18 years or older (group A) and an open-label cohort in participants 60 years and older (group B), who had received three doses of inactivated whole-virion vaccines at least 6 months before enrolment. Pregnant women and people with major chronic illnesses or a history of allergies were excluded. Eligible participants in group A were stratified by age (18-59 years and ≥60 years) and then randomised by SAS 9.4 in a ratio of 3:1 to receive a dose of the mRNA vaccine (CS-2034, CanSino, Shanghai, China) or inactivated vaccine (BBIBP-CorV, Sinopharm, Beijing, China). Safety and immunogenicity against omicron variants of the fourth dose were evaluated in group A. Participants 60 years and older were involved in group B for safety observations. The primary outcome was geometric mean titres (GMTs) of the neutralising antibodies against omicron and seroconversion rates against BA.5 variant 28 days after the boosting, and incidence of adverse reactions within 28 days. The intention-to-treat group was involved in the safety analysis, while all patients in group A who had blood samples taken before and after the booster were involved in the immunogenicity analysis. This trial was registered at the Chinese Clinical Trial Registry Centre (ChiCTR2200064575).

FINDINGS

Between Oct 13, and Nov 22, 2022, 320 participants were enrolled in group A (240 in the CS-2034 group and 80 in the BBIBP-CorV group) and 113 in group B. Adverse reactions after vaccination were more frequent in CS-2034 recipients (158 [44·8%]) than BBIBP-CorV recipients (17 [21·3%], p<0·0001). However, most adverse reactions were mild or moderate, with grade 3 adverse reactions only reported by eight (2%) of 353 participants receiving CS-2034. Heterologous boosting with CS-2034 elicited 14·4-fold (GMT 229·3, 95% CI 202·7-259·4 vs 15·9, 13·1-19·4) higher concentration of neutralising antibodies to SARS-CoV-2 omicron variant BA.5 than did homologous boosting with BBIBP-CorV. The seroconversion rates of SARS-CoV-2-specific neutralising antibody responses were much higher in the mRNA heterologous booster regimen compared with BBIBP-CorV homologous booster regimen (original strain 47 [100%] of 47 vs three [18·8%] of 16; BA.1 45 [95·8%] of 48 vs two [12·5%] 16; and BA.5 233 [98·3%] of 240 vs 15 [18·8%] of 80 by day 28).

INTERPRETATION

Both the administration of mRNA vaccine CS-2034 and inactivated vaccine BBIBP-CorV as a fourth dose were well tolerated. Heterologous boosting with mRNA vaccine CS-2034 induced higher immune responses and protection against symptomatic SARS-CoV-2 omicron infections compared with homologous boosting, which could support the emergency use authorisation of CS-2034 in adults.

FUNDING

Science and Technology Commission of Shanghai, National Natural Science Foundation of China, Jiangsu Provincial Science Fund for Distinguished Young Scholars, and Jiangsu Provincial Key Project of Science and Technology Plan.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Safety and immunogenicity of aerosolised Ad5-nCoV, intramuscular Ad5-nCoV, or inactivated COVID-19 vaccine CoronaVac given as the second booster following three doses of CoronaVac: a multicentre, open-label, phase 4, randomised trial

BACKGROUND

Aerosolised Ad5-nCoV is the first approved mucosal respiratory COVID-19 vaccine to be used as a booster after the primary immunisation with COVID-19 vaccines. This study aimed to evaluate the safety and immunogenicity of aerosolised Ad5-nCoV, intramuscular Ad5-nCoV, or inactivated COVID-19 vaccine CoronaVac given as the second booster.

METHODS

This is an open-label, parallel-controlled, phase 4 randomised trial enrolling healthy adult participants (≥18 years) who had completed a two-dose primary immunisation and a booster immunisation with inactivated COVID-19 vaccines (CoronaVac only) at least 6 months before, in Lianshui and Donghai counties, Jiangsu Province, China. We recruited eligible participants from previous trials in China (NCT04892459, NCT04952727, and NCT05043259) as cohort 1 (with the serum before and after the first booster dose available), and from eligible volunteers in Lianshui and Donghai counties, Jiangsu Province, as cohort 2. Participants were randomly assigned at a ratio of 1:1:1, using a web-based interactive response randomisation system, to receive the fourth dose (second booster) of aerosolised Ad5-nCoV (0·1 mL of 1·0 × 1011 viral particles per mL), intramuscular Ad5-nCoV (0·5 mL of 1·0 × 1011 viral particles per mL), or inactivated COVID-19 vaccine CoronaVac (0·5 mL), respectively. The co-primary outcomes were safety and immunogenicity of geometric mean titres (GMTs) of serum neutralising antibodies against prototype live SARS-CoV-2 virus 28 days after the vaccination, assessed on a per-protocol basis. Non-inferiority or superiority was achieved when the lower limit of the 95% CI of the GMT ratio (heterologous group vs homologous group) exceeded 0·67 or 1·0, respectively. This study was registered with ClinicalTrials.gov, NCT05303584 and is ongoing.

FINDINGS

Between April 23 and May 23, 2022, from 367 volunteers screened for eligibility, 356 participants met eligibility criteria and received a dose of aerosolised Ad5-nCoV (n=117), intramuscular Ad5-nCoV (n=120), or CoronaVac (n=119). Within 28 days of booster vaccination, participants in the intramuscular Ad5-nCoV group reported a significantly higher frequency of adverse reactions than those in the aerosolised Ad5-nCoV and intramuscular CoronaVac groups (30% vs 9% and 14%, respectively; p<0·0001). No serious adverse events related to the vaccination were reported. The heterologous boosting with aerosolised Ad5-nCoV triggered a GMT of 672·4 (95% CI 539·7-837·7) and intramuscular Ad5-nCoV triggered a serum neutralising antibody GMT of 582·6 (505·0-672·2) 28 days after the booster dose, both of which were significantly higher than the GMT in the CoronaVac group (58·5 [48·0-71·4]; p<0·0001).

INTERPRETATION

A heterologous fourth dose (second booster) with either aerosolised Ad5-nCoV or intramuscular Ad5-nCoV was safe and highly immunogenic in healthy adults who had been immunised with three doses of CoronaVac.

FUNDING

National Natural Science Foundation of China, Jiangsu Provincial Science Fund for Distinguished Young Scholars, and Jiangsu Provincial Key Project of Science and Technology Plan.

Immunogenicity and safety of heterologous immunisation with Ad5-nCOV in healthy adults aged 60 years and older primed with an inactivated SARS-CoV-2 vaccine (CoronaVac): a phase 4, randomised, observer-blind, non-inferiority trial

Background

People over 60 have been found to develop less protection after two doses of inactivated COVID-19 vaccines than younger people. Heterologous immunisation could potentially induce more robust immune responses compared to homologous immunisation. We aimed to assess the immunogenicity and safety of a heterologous immunisation with an adenovirus type 5-vectored vaccine (Ad5-nCOV, Convidecia) among elderly who were primed with an inactivated vaccine (CoronaVac) previously.

Methods

We did a randomised, observer-blinded, non-inferiority trial in healthy adults aged 60 years and older in Lianshui County (Jiangsu, China) between August 26, 2021 and May 15, 2022. 199 eligible participants who had received two doses of CoronaVac in the past 3-6 months were randomised (1:1) to receive a third dose of Convidecia (group A, n = 99) or CoronaVac (group B, n = 100), while 100 participants primed with one dose of CoronaVac in the past 1-2 months were randomised equally to receive a second dose of Convidecia (group C, n = 50) or CoronaVac (group D, n = 50). Participants and investigators were masked to the vaccine received. Primary outcomes were the geometric mean titers (GMTs) of neutralising antibodies against live SARS-CoV-2 virus 14 days after boosting and 28-day adverse reactions. This study was registered with ClinicalTrials.govNCT04952727.

Findings

A heterologous third dose of Convidecia resulted in a 6.2-fold (GMTs: 286.4 vs 48.2), 6.3-fold (45.9 vs 7.3) and 7.5-fold (32.9 vs 4.4) increase in neutralising antibodies against SARS-CoV-2 wild-type, delta (B.1.617.2) and omicron (BA.1.1) 14 days post boosting, respectively, compared with the homologous boost. The heterologous booster with Convidecia induced significantly higher neutralsing activities, with up to 91% inhibition in binding of Spike to ACE2 for BA.4 and BA.5 variants, compared with 35% inhibition induced by three doses of CoronaVac. For participants primed with one dose of CoronaVac, a heterologous dose of Convidecia induced higher neutralising antibodies against wild-type than two doses of CoronaVac (GMTs: 70.9 vs 9.3, p < 0.0001), but not for that against variants of concern (GMTs against delta: 5.0 vs 4.0, p = 0.4876; GMTs against omicron: 4.8 vs 3.7, p = 0.4707). Adverse reactions were reported by 8 (8.1%) participants in group A and 4 (4.0%) in group B (p ＞ 0.05), and 8 (16.0%) in group C and 1 (2.0%) in group D (p = 0.031).

Interpretation

In elderly individuals primed with two doses of CoronaVac, the heterologous immunisation with Convidecia induced strong antibodies against SARS-CoV-2 wildtype and variants of concern, which could be an alternative regimen for enhancing protection in this vulnerable population.

Funding

National Natural Science Foundation of China, Jiangsu Provincial Key Research and Development Program, and Jiangsu Science Fund for Distinguished Young Scholars Program.

Safety and immunogenicity of heterologous boosting with orally aerosolised or intramuscular Ad5-nCoV vaccine and homologous boosting with inactivated vaccines (BBIBP-CorV or CoronaVac) in children and adolescents: a randomised, open-label, parallel-controlled, non-inferiority, single-centre study

BACKGROUND

Heterologous booster immunisation with orally administered aerosolised Ad5-nCoV vaccine (AAd5) has been shown to be safe and highly immunogenic in adults. Here, we aimed to assess the safety and immunogenicity of heterologous booster immunisation with orally administered AAd5 in children and adolescents aged 6-17 years who had received two doses of inactivated vaccine (BBIBP-CorV or CoronaVac).

METHODS

We did a randomised, open-label, parallel-controlled, non-inferiority study to assess the safety and immunogenicity of heterologous booster immunisation with AAd5 (0·1 mL) or intramuscular Ad5-nCoV vaccine (IMAd5; 0·3 mL) and homologous booster immunisation with inactivated vaccine (BBIBP-CorV or CoronaVac; 0·5 mL) in children (aged 6-12 years) and adolescents (aged 13-17 years) who had received two doses of inactivated vaccine at least 3 months earlier in Hunan, China. Children and adolescents who were previously immunised with two-dose BBIBP-CorV or CoronaVac were recruited for eligibility screening at least 3 months after the second dose. A stratified block method was used for randomisation, and participants were stratified by age and randomly assigned (3:1:1) to receive AAd5, IMAd5, or inactivated vaccine. The study staff and participants were not masked to treatment allocation. Laboratory and statistical staff were masked during the study. In this interim analysis, adverse events within 14 days and geometric mean titre (GMT) of serum neutralising antibodies on day 28 after the booster vaccination, based on the per-protocol population, were used as the primary outcomes. The analysis of non-inferiority was based on comparison using a one-sided 97·5% CI with a non-inferiority margin of 0·67. This study was registered at ClinicalTrials.gov, NCT05330871, and is ongoing.

FINDINGS

Between April 17 and May 28, 2022, 436 participants were screened and 360 were enrolled: 220 received AAd5, 70 received IMAd5, and 70 received inactivated vaccine. Within 14 days after booster vaccination, vaccine-related adverse reactions were reported: 35 adverse events (in 13 [12%] of 110 children and 22 [20%] of 110 adolescents) in 220 individuals in the AAd5 group, 35 (in 18 [51%] of 35 children and 17 [49%] of 35 adolescents) in 70 individuals in the IMAd5 group, and 13 (in five [14%] of 35 children and eight [23%] of 35 adolescents) in 70 individuals in the inactivated vaccine group. Solicited adverse reactions were also reported: 34 (13 [12%] of 110 children and 21 [10%] of 110 adolescents) in 220 individuals in the AAd5 group, 34 (17 [49%] of 35 children and 17 [49%] of 35 adolescents) in 70 individuals in the IMAd5 group, and 12 (five [14%] of 35 children and seven [20%] of 35 adolescents) in 70 individuals in the inactivated vaccine group. The GMTs of neutralising antibodies against ancestral SARS-CoV-2 Wuhan-Hu-1 (Pango lineage B) in the AAd5 group were significantly higher than the GMTs in the inactivated vaccine group (adjusted GMT ratio 10·2 [95% CI 8·0-13·1]; p<0·0001).

INTERPRETATION

Our study shows that a heterologous booster with AAd5 is safe and highly immunogenic against ancestral SARS-CoV-2 Wuhan-Hu-1 in children and adolescents.

FUNDING

National Key R&D Program of China.

[Immunogenicity of group A+C meningococcal polysaccharide conjugate vaccine in infants: A phase Ⅲ clinical trial study]

Objective: To evaluate the immunogenicity of group A+C meningococcal polysaccharide conjugate vaccine in infants under 2 years old. Methods: From March 2017 to June 2018, 1 932 healthy infants in Biyang County, Henan Province, who were not vaccinated with meningococcal meningitis vaccine and whose axillary temperature was ≤37.0 ℃, were recruited as participants. The 3 months and 6-11 months old infants were allocated to the experiment group and the control group in a ratio of 1∶1. Infants aged 12-23 months were allocated to the 1-dose group, the 2-dose group and the control group in a ratio of 1∶1∶1, with 276 infants in each group. The infants in the experiment group were intramuscularly injected with freeze-dried group A+C meningococcal polysaccharide conjugate vaccine to be evaluated, and infants in the control group received intramuscular injection of commercially available freeze-dried group A+C meningococcal conjugate vaccine. The venous blood of infants was collected 30 days before the first dose and after the last dose of inoculation, and the antibody seroconversion of each group was determined and compared. Results: The completion rate of immunogenicity study was 95.2% (1 839/1 932). Before inoculation, there was no statistical difference in the geometric mean titer and positive rate of group A+C antibodies between the experiment group and the control group in 3 months and 6-11 months old infants (all P values >0.05). The geometric mean titers and positive rate of group A antibodies in the 1-dose group were higher than those in the control group (all P values <0.05), but there was no statistical difference between the 2-dose group and the control group (all P values >0.05) in infants aged 12-23 months. After inoculation, the differences (95%CI) in the positive conversion rate of group A+C antibodies between the experiment group and the control group were -0.12% (-6.01%-5.77%) and 0.82% (-4.23%-5.86%) in the 3 months old infants. At the age of 6-11 months, the differences were 6.75% (1.71%-11.79%) and -4.32% (-8.73%-0.08%), respectively. At the age of 12-23 months, the differences were 1.02% (-3.80%-5.83%) and -4.40% (-7.79%- -1.01%) in the 2-dose group and -7.22% (-12.90%- -1.54%) and -18.61% (-23.75%- -13.46%) in the 1-dose group, respectively. The geometric mean titers of group A+C antibodies in the 3 months old infants were 48.50 and 63.12, respectively, which had no significant difference from the control group (43.02 and 57.99, respectively) (both P values <0.05). The geometric mean titers of group A+C antibodies in the 6-11 months and 12-23 months old infants were 84.09 and 92.51 (2-dose group), which were higher than those in the corresponding control group (43.10 and 61.83, respectively) (all P values <0.001). Conclusion: Group A+C meningococcal conjugate vaccine has good immunogenicity in infants under 2 years old.

[ Ⅲ ]

Objective: The aim of this study was to evaluate the safety and immunogenicity of the first domestic ACYW135 meningococcal conjugate vaccine and a control vaccine named AC group meningococcal conjugate vaccine for 3 months (90-119 days) infants. Methods: From February 2017 to June 2018, a randomized, blinded, and similar vaccine-controlled clinical trial design was adopted at the Henan Vaccine Clinical Research Base. The subjects were 3 months old healthy infants, a total of 720, based on a 1∶1 ratio. The random allocation table for entry was randomly assigned to the experimental group and the control group. According to the 3, 4, and 5 month-old vaccination procedures, the subjects were vaccinated with test vaccine (ACYW135 group meningococcal conjugate vaccine) and control vaccine (group A group C meningococcal polysaccharide conjugate vaccine), of which 720 were given the first dose, 696 were given the second dose (test group: 346; control group: 350), and 692 were given the third dose (test group: 344; Control group: 348). Results: The overall adverse reaction rate of the test vaccine was 21.90% (230 cases), which was lower than the 32.04% (339 cases) of the control vaccine (P<0.001). The incidence of systemic adverse reactions was 19.52% (205 cases), which was lower than that of the control vaccine (27.69%) (293 cases) (P<0.001). The local adverse reaction rate was 3.04% (32 cases), which was lower than the control group (7.84%) (83 cases) (P<0.001). The graded adverse reaction test vaccine was 0.57% (6 cases), which was lower than the control group of 2.36% (25 cases) (P<0.001). The positive conversion rate of anti-bacterial serum antibodies showed that there was no significant difference between the test vaccine group A (91.42%), C (88.76%) and the control vaccine (92.92%) (87.02%) (P>0.05). Group Y and W135 was 88.17% (298 cases), 99.41% (336 cases), respectively. The GMT results showed that the test vaccine group A was 56.24, the control vaccine was 57.43 (P>0.05); the group C test vaccine (43.53) was higher than the control group (27.28) (P<0.001). The group Y and W135 are 89.22 and 140.66, respectively. Among them, the proportion of the group C GMT antibody ≥ 1∶128 for test vaccine (31.07%, 105 cases) was higher than the control vaccine (16.22%, 55 cases) (P<0.001). Conclusion: ACYW135 group meningococcal conjugate vaccine has more safety and immunogenicity after application to 3 month old infants.

Immunogenicity and safety of a recombinant adenovirus type-5-vectored COVID-19 vaccine in healthy adults aged 18 years or older: a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

This is the first randomised controlled trial for assessment of the immunogenicity and safety of a candidate non-replicating adenovirus type-5 (Ad5)-vectored COVID-19 vaccine, aiming to determine an appropriate dose of the candidate vaccine for an efficacy study.

METHODS

This randomised, double-blind, placebo-controlled, phase 2 trial of the Ad5-vectored COVID-19 vaccine was done in a single centre in Wuhan, China. Healthy adults aged 18 years or older, who were HIV-negative and previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-free, were eligible to participate and were randomly assigned to receive the vaccine at a dose of 1 × 10¹¹ viral particles per mL or 5 × 10¹⁰ viral particles per mL, or placebo. Investigators allocated participants at a ratio of 2:1:1 to receive a single injection intramuscularly in the arm. The randomisation list (block size 4) was generated by an independent statistician. Participants, investigators, and staff undertaking laboratory analyses were masked to group allocation. The primary endpoints for immunogenicity were the geometric mean titres (GMTs) of specific ELISA antibody responses to the receptor binding domain (RBD) and neutralising antibody responses at day 28. The primary endpoint for safety evaluation was the incidence of adverse reactions within 14 days. All recruited participants who received at least one dose were included in the primary and safety analyses. This study is registered with ClinicalTrials.gov, NCT04341389.

FINDINGS

603 volunteers were recruited and screened for eligibility between April 11 and 16, 2020. 508 eligible participants (50% male; mean age 39·7 years, SD 12·5) consented to participate in the trial and were randomly assigned to receive the vaccine (1 × 10¹¹ viral particles n=253; 5 × 10¹⁰ viral particles n=129) or placebo (n=126). In the 1 × 10¹¹ and 5 × 10¹⁰ viral particles dose groups, the RBD-specific ELISA antibodies peaked at 656·5 (95% CI 575·2-749·2) and 571·0 (467·6-697·3), with seroconversion rates at 96% (95% CI 93-98) and 97% (92-99), respectively, at day 28. Both doses of the vaccine induced significant neutralising antibody responses to live SARS-CoV-2, with GMTs of 19·5 (95% CI 16·8-22·7) and 18·3 (14·4-23·3) in participants receiving 1 × 10¹¹ and 5 × 10¹⁰ viral particles, respectively. Specific interferon γ enzyme-linked immunospot assay responses post vaccination were observed in 227 (90%, 95% CI 85-93) of 253 and 113 (88%, 81-92) of 129 participants in the 1 × 10¹¹ and 5 × 10¹⁰ viral particles dose groups, respectively. Solicited adverse reactions were reported by 183 (72%) of 253 and 96 (74%) of 129 participants in the 1 × 10¹¹ and 5 × 10¹⁰ viral particles dose groups, respectively. Severe adverse reactions were reported by 24 (9%) participants in the 1 × 10¹¹ viral particles dose group and one (1%) participant in the 5 × 10¹⁰ viral particles dose group. No serious adverse reactions were documented.

INTERPRETATION

The Ad5-vectored COVID-19 vaccine at 5 × 10¹⁰ viral particles is safe, and induced significant immune responses in the majority of recipients after a single immunisation.

FUNDING

National Key R&D Programme of China, National Science and Technology Major Project, and CanSino Biologics.

Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial

BACKGROUND

A vaccine to protect against COVID-19 is urgently needed. We aimed to assess the safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 (Ad5) vectored COVID-19 vaccine expressing the spike glycoprotein of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain.

METHODS

We did a dose-escalation, single-centre, open-label, non-randomised, phase 1 trial of an Ad5 vectored COVID-19 vaccine in Wuhan, China. Healthy adults aged between 18 and 60 years were sequentially enrolled and allocated to one of three dose groups (5 × 10¹⁰, 1 × 10¹¹, and 1·5 × 10¹¹ viral particles) to receive an intramuscular injection of vaccine. The primary outcome was adverse events in the 7 days post-vaccination. Safety was assessed over 28 days post-vaccination. Specific antibodies were measured with ELISA, and the neutralising antibody responses induced by vaccination were detected with SARS-CoV-2 virus neutralisation and pseudovirus neutralisation tests. T-cell responses were assessed by enzyme-linked immunospot and flow-cytometry assays. This study is registered with ClinicalTrials.gov, NCT04313127.

FINDINGS

Between March 16 and March 27, 2020, we screened 195 individuals for eligibility. Of them, 108 participants (51% male, 49% female; mean age 36·3 years) were recruited and received the low dose (n=36), middle dose (n=36), or high dose (n=36) of the vaccine. All enrolled participants were included in the analysis. At least one adverse reaction within the first 7 days after the vaccination was reported in 30 (83%) participants in the low dose group, 30 (83%) participants in the middle dose group, and 27 (75%) participants in the high dose group. The most common injection site adverse reaction was pain, which was reported in 58 (54%) vaccine recipients, and the most commonly reported systematic adverse reactions were fever (50 [46%]), fatigue (47 [44%]), headache (42 [39%]), and muscle pain (18 [17%]. Most adverse reactions that were reported in all dose groups were mild or moderate in severity. No serious adverse event was noted within 28 days post-vaccination. ELISA antibodies and neutralising antibodies increased significantly at day 14, and peaked 28 days post-vaccination. Specific T-cell response peaked at day 14 post-vaccination.

INTERPRETATION

The Ad5 vectored COVID-19 vaccine is tolerable and immunogenic at 28 days post-vaccination. Humoral responses against SARS-CoV-2 peaked at day 28 post-vaccination in healthy adults, and rapid specific T-cell responses were noted from day 14 post-vaccination. Our findings suggest that the Ad5 vectored COVID-19 vaccine warrants further investigation.

FUNDING

National Key R&D Program of China, National Science and Technology Major Project, and CanSino Biologics.