Safety and immunogenicity of SW-BIC-213, a modified COVID-19 Lipo-Polyplex mRNA vaccine, in Laotian healthy adults aged 18 years and above: a Phase 1/2 trial (preprint)

Background The mRNA vaccine against SARS-CoV-2 has demonstrated remarkable efficacy in protecting against coronavirus disease 2019 (COVID-19), including providing high protection against severe disease during the emergence of variant waves. In this study, we aimed to investigate the safety and immunogenicity of a 2-dose regimen of the LPP-based mRNA vaccine, SW-BIC-213, in Laos. Methods For this phase 1/2 clinical trial, we recruited healthy adults aged 18-60 years (phase 1) or [≥]18 years (phase 2) from Mahosot Hospital (Vientiane) and Champhone District Hospital (Savannakhet). Participants with SARS-CoV-2 infection, previous COVID-19 vaccination, known allergies to any vaccine component, or pregnancy were excluded. In the phase 1 trial, 41 eligible participants were sequentially assigned to either the 25 g dose group (25 g) or the 45 g dose group (45 g) in accordance with their enrollment order, with 21 participants in 45 g dose group and 20 participants in 25 g dose group. In the phase 2 trial, 480 participants were randomly allocated (2:2:1 ratio) to either the 25 g dose group, 45 g dose group, or placebo group. The primary endpoints for the phase 1 trial were the incidence of local/systemic solicited adverse reactions/events (0-6 days after each vaccination dose), unsolicited adverse events (0-21 days and 0-28 days after the first and second dose of immunization, respectively), and serious adverse events from the first dose of vaccination to 28 days after completing the full course of immunization. In the phase 2 trial, the primary endpoints were the seroconversion rate and geometric mean titer (GMT) of SARS-CoV-2 S-protein specific IgG antibodies and neutralizing antibodies 14 days after the second dose in participants. As for neutralizing antibodies, we detected pseudo-virus neutralizing antibody against wild type (WT), Delta, BA.1 and BA.2. We also detected live viral neutralizing antibody against WT strain 14 days after the second dose. Furthermore, the safety endpoints were also measured during the trial. This seamless phase 1/2 trial was registered with ClinicalTrials.gov under the identifier NCT05144139. Results Between December 3, 2021, and March 31, 2022, a total of 41 participants were recruited in the phase 1 trial, while the phase 2 trial enrolled 480 participants from January 20 to July 6, 2022. In the phase 1 trial, a total of 32 subjects (80.0%) reported 103 cases of adverse reactions. All adverse reactions were limited to Grade 1-2. In the phase 2 trial, a total of 479 subjects, 372 subjects (77.7%) reported 929 cases of adverse reactions. All adverse reactions in severity of Grade 3 were manifested as fever (3.4%, 2.1% and 2.9% in 45 g dose, 25 g dose and placebo group respectively, only observed in adults), except which all other reactions were limited to Grade 1-2. All adverse reactions noted during the study were tolerable, predominantly transient, and resolved spontaneously. No serious adverse events (SAEs) related to vaccination were observed. In Phase 2 study, SW-BIC-213 could elicit a high level of seroconversion rate of pseudo-virus neutralizing antibody against WT (100.0% in 25 g dose group, 99.3% in 45 g dose group), Delta (99.2% in 25 g dose group, 98.0% in 45 g dose group), Omicron BA.1 (84.1% in 25 g dose group, 84.7% in 45 g dose group) and Omicron BA.2 (96.0% in 25 g dose group, 88.8% in 45 g dose group) at 14 days after the second dose. The pseudo-virus neutralizing antibody titer against WT, Delta, BA.1 and BA.2 was all significant higher (P<0.0001) in both 45 g dose group (1175.02, 620.62, 72.39 and 172.80) and 25 g dose group (885.80, 579.40, 47.24 and 101.96) compared with the placebo group (9.67, 10.66, 13.99 and 29.53) at 14 days after the second dose. As for live viral neutralizing antibodies against WT strain, the seroconversion rate could reach more than 94% at 14 days after second dose. The neutralizing antibody titer against WT strain was significantly higher (P<0.0001) in both 45 g dose group (315.00) and 25 g dose group (323.18) compared with the placebo group (8.51) at 14 days after second dose. Conclusion: COVID-19 mRNA vaccine SW-BIC-213 manifests a favorable safety profile and is highly immunogenic in eligible subjects aged [≥]18 years.

Antibody Persistence and Safety through 6 Months after Heterologous Orally Aerosolised Ad5-nCoV in individuals primed with two-dose CoronaVac previously (preprint)

Background: Heterologous orally administered adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) in individuals who were primed with two-dose CoronaVac (an inactivated SARS-CoV-2 vaccine, by Sinovac) previously, has been reported to be safe and highly immunogenic within 28 days post-boosting. However, antibody persistence and safety up to 6 months of this regimen are not been reported yet. Methods: This is a randomized, open label, single-center trial on safety and immunogenicity of heterologous boost immunization with an orally administered aerosolised Ad5-nCoV vs. homologous boost immunization with CoronaVac after two-dose priming with CoronaVac in Chinese adults aged 18 years and older (NCT05043259). We followed the participants in this trial, including 140 in the low-dose aerosolised Ad5-nCoV group, 139 in the high-dose aerosolised Ad5-nCoV group, and 140 in the CoronaVac group for 6 months. Neutralising antibodies (NAbs) against live wild-type SARS-CoV-2 virus and omicron variant, and receptor-binding domain (RBD)-specific IgG antibodies were detected in serum samples collected at 28 days, 3 months, and 6 months after the booster dose. Serious adverse events (SAEs) were documented till month 6. Results: The low-dose and high-dose heterologous boost immunisation groups had NAb GMTs against live wild-type SARS-CoV-2 of 1937.3 [95% CI 1466.9, 2558.4] and 1350.8 [95% CI 952.6, 1915.3], which were 26.4 folds and 18.4 folds higher than that the CoronaVac group did (73.5 [95%CI 52.3, 103.3]) at 28 days. The low-dose and high-dose heterologous boost immunisation groups had NAb GMTs against live wild-type SARS-CoV-2 of 530.1 (95% CI 412.5, 681.1) and 457.6 (95%CI 349.4, 599.2), which were 26.0 folds and 22.4 folds higher than that the CoronaVac group did (20.4 [95%CI 14.3, 29.1]) at 3 months, respectively. At 6 months, the low-dose and high-dose heterologous booster groups had NAb GMTs against live wild-type SARS-CoV-2 of 312.9 (95%CI 237.7, 411.8) and 251.1 (95%CI 178.2, 354.0), which were 30.1 folds and 24.1 folds higher than the CoronaVac group did (10.4 [95%CI 7.8, 14.0]), respectively. Additionally, the low-dose and high-dose heterologous booster groups had NAb GMTs against live omicron variant of 52.0 (95%CI 37.2, 72.6) and 23.1 (95%CI 15.7, 33.9) at 28 days, 27.9 (95% CI 18.8, 41.3) and 23.3 (95%CI 16.2, 33.3) at 3 months, 16.0 (95%CI 10.9, 23.5) and 12.0 (95%CI 8.5, 16.8) at 6 months, respectively. However, nearly all participants had no detectable NAbs for omicron variant in the CoronaVac group at either 28 days, 3 months, or 6 months. No vaccine-related SAEs were observed. Conclusions: These data suggested that heterologous aerosolised Ad5-nCoV following two-dose CoronaVac priming was safe and persistently more immunogenic than three-dose CoronaVac, although immune responses waned over time.

Safety and immunogenicity of heterologous boost immunization with an adenovirus type-5-vectored and protein-subunit-based COVID-19 vaccine (Convidecia/ZF2001): a randomized, observer-blinded, placebo-controlled trial (preprint)

Background Heterologous boost vaccination has been proposed as an option to elicit stronger and broader, or longer-lasting immunity. We assessed the safety and immunogenicity of heterologous immunization with a recombinant adenovirus type-5-vectored COVID-19 vaccine (Convidecia) and a protein-subunit-based COVID-19 vaccine (ZF2001). Methods and Findings We did a randomized, observer-blinded, placebo-controlled trial in healthy adults previously received one dose of Convidecia. Participants were randomly assigned (2:1) to receive either ZF2001 (vaccine group) or a trivalent inactivated influenza vaccine (TIV) (placebo group) at either 28-day or 56-day intervals. For both regimens, all participants received the 2nd injection with ZF2001 at 4 months after a dose of ZF2001 or TIV, with three-dose schedules of Convidecia/Convidecia/ZF2001 at day 0, day 28 and month 5 (referred to as CV/ZF/ZF (D0-D28-M5)) and CV/ZF/ZF (D0-D56-M6), and two-dose schedules of CV/ZF (D0-M5) and CV/ZF (D0-M6). The primary outcome was the geometric mean titer (GMT) of the neutralizing antibodies against live SARS-CoV-2 virus 14 days after each boost vaccination. The safety outcome was 7-day reactogenicity, measured as solicited local or systemic adverse reactions after each vaccination. Between April 7, 2021, and May 6, 2021, 120 participants were enrolled, among whom 60 were randomly assigned to receive ZF2001 (n=40) or TIV (n=20) at a 28-day interval, and 60 were randomly assigned to receive ZF2001 (n=40) or TIV (n=20) at a 56-day interval. 113 (94.2%) participants received the 2nd injection with ZF2001 4 months after a dose of ZF2001 or TIV. A total of 26 participants (21.7%) reported solicited adverse events within 7 days post boost vaccinations, and all the reported adverse reactions were mild . Among participants receiving ZF001 as second dose, the GMTs of neutralizing antibodies increased to 58.4 IU/ml (42.8-79.8) in 0-28 regimen, and to 80.8 IU/ml (53.1-122.9) in 0-56 regimen at 14 days post first boost dose. The GMTs of neutralizing antibodies increased to 334.9 IU/ml (95% CI 230.4, 486.9) in C/Z/Z (D0-D28-M5) regimen, and 441.2 IU/ml (260.8, 746.4) in C/Z/Z (D0-D56-M6) regimen at 14 days after the third dose. Two-dose schedules of CV/ZF (D0-M5) and CV/ZF (D0-M6) induced comparable antibody level comparable with that elicited by three-dose schedules, with the GMTs of 282.9 IU/ml (142.5, 561.8) and 293.9 IU/ml (137.6, 627.9), respectively. Study limitations include the absence of vaccine effectiveness in real-world, and current lack of immune persistence data and the neutralizing antibodies to Omicron. Conclusions Heterologous boosting with ZF001 following primary vaccination of Convidecia is safe and more immunogenic than a single dose of Convidecia. These results support flexibility in cooperating viral vectored vaccines and recombinant protein vaccine. Trial Registration ClinicalTrial.gov NCT04833101

Heterologous prime-boost immunization with CoronaVac and Convidecia (preprint)

ABSTRACT Background The safety and immunogenicity of heterologous prime-boost COVID-19 vaccine regimens with one shot of a recombinant adenovirus type-5-vectored COVID-19 vaccine Convidecia has not been reported. Methods We conducted a randomized, controlled, observer-blinded trial of heterologous prime-boost immunization with CoronaVac and Convidecia in healthy adults 18-59 years of age. Eligible participants who were primed with one or two doses of CoronaVac were randomly assigned at a 1:1 ratio to receive a booster dose of Convidecia or CoronaVac. Participants were masked to the vaccine received but not to the three-dose or two-dose regimen. The occurrences of adverse reactions within 28 days after the vaccination were documented. The geometric mean titers of neutralizing antibodies against live SARS-CoV-2 virus were measured at 14 and 28 days after the booster vaccination. Results Between May 25 and 26, 2021, a total of 300 participants were enrolled. Participants who received a booster shot with a heterologous dose of Convidecia reported increased frequencies of solicited injection-site reactions than did those received a homogeneous dose of CoronaVac, but frequencies of systemic reactions. The adverse reactions were generally mild to moderate. The heterologous immunization with Convidecia induced higher live viral neutralizing antibodies than did the homogeneous immunization with CoronaVac (197.4[167.7, 232.4] vs. 33.6[28.3, 39.8] and 54.4[37. 9, 78.0] vs. 12.8[9.3, 17.5]) at day 14 in the three- and two-dose regimen cohort, respectively. Conclusions The heterologous prime-boost regimen with Convidecia after the priming with CoronaVac was safe and significantly immunogenic than a homogeneous boost with CoronaVac ( ClinicalTrials.gov , number NCT04892459 ).