Effect of priming interval on reactogenicity, peak immunological response, and waning after homologous and heterologous COVID-19 vaccine schedules: exploratory analyses of Com-COV, a randomised control trial.

Priming COVID-19 vaccine schedules have been deployed at variable intervals globally, which might influence immune persistence and the relative importance of third-dose booster programmes. Here, we report exploratory analyses from the Com-COV trial, assessing the effect of 4-week versus 12-week priming intervals on reactogenicity and the persistence of immune response up to 6 months after homologous and heterologous priming schedules using the vaccines BNT162b2 (tozinameran, Pfizer/BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca). Com-COV was a participant-masked, randomised immunogenicity trial. For these exploratory analyses, we used the trial's general cohort, in which adults aged 50 years or older were randomly assigned to four homologous and four heterologous vaccine schedules using BNT162b2 and ChAdOx1 nCoV-19 with 4-week or 12-week priming intervals (eight groups in total). Immunogenicity analyses were done on the intention-to-treat (ITT) population, comprising participants with no evidence of SARS-CoV-2 infection at baseline or for the trial duration, to assess the effect of priming interval on humoral and cellular immune response 28 days and 6 months post-second dose, in addition to the effects on reactogenicity and safety. The Com-COV trial is registered with the ISRCTN registry, 69254139 (EudraCT 2020-005085-33). Between Feb 11 and 26, 2021, 730 participants were randomly assigned in the general cohort, with 77-89 per group in the ITT analysis. At 28 days and 6 months post-second dose, the geometric mean concentration of anti-SARS-CoV-2 spike IgG was significantly higher in the 12-week interval groups than in the 4-week groups for homologous schedules. In heterologous schedule groups, we observed a significant difference between intervals only for the BNT162b2-ChAdOx1 nCoV-19 group at 28 days. Pseudotyped virus neutralisation titres were significantly higher in all 12-week interval groups versus 4-week groups, 28 days post-second dose, with geometric mean ratios of 1·4 (95% CI 1·1-1·8) for homologous BNT162b2, 1·5 (1·2-1·9) for ChAdOx1 nCoV-19-BNT162b2, 1·6 (1·3-2·1) for BNT162b2-ChAdOx1 nCoV-19, and 2·4 (1·7-3·2) for homologous ChAdOx1 nCoV-19. At 6 months post-second dose, anti-spike IgG geometric mean concentrations fell to 0·17-0·24 of the 28-day post-second dose value across all eight study groups, with only homologous BNT162b2 showing a slightly slower decay for the 12-week versus 4-week interval in the adjusted analysis. The rank order of schedules by humoral response was unaffected by interval, with homologous BNT162b2 remaining the most immunogenic by antibody response. T-cell responses were reduced in all 12-week priming intervals compared with their 4-week counterparts. 12-week schedules for homologous BNT162b2 and ChAdOx1 nCoV-19-BNT162b2 were up to 80% less reactogenic than 4-week schedules. These data support flexibility in priming interval in all studied COVID-19 vaccine schedules. Longer priming intervals might result in lower reactogenicity in schedules with BNT162b2 as a second dose and higher humoral immunogenicity in homologous schedules, but overall lower T-cell responses across all schedules. Future vaccines using these novel platforms might benefit from schedules with long intervals. UK Vaccine Taskforce and National Institute for Health and Care Research.

Shaw RH ，Liu X ，Stuart ASV ，Greenland M ，Aley PK ，Andrews NJ ，Cameron JC ，Charlton S ，Clutterbuck EA ，Collins AM ，Dejnirattisai W ，Dinesh T ，Faust SN ，Ferreira DM ，Finn A ，Green CA ，Hallis B ，Heath PT ，Hill H ，Lambe T ，Lazarus R ，Libri V ，Long F ，Mujadidi YF ，Plested EL ，Morey ER ，Provstgaard-Morys S ，Ramasamy MN ，Ramsay M ，Read RC ，Robinson H ，Screaton GR ，Singh N ，Turner DPJ ，Turner PJ ，Vichos I ，Walker LL ，White R ，Nguyen-Van-Tam JS ，Snape MD ，Com-COV Study Group ... -  《-》

Safety and immunogenicity of heterologous versus homologous prime-boost schedules with an adenoviral vectored and mRNA COVID-19 vaccine (Com-COV): a single-blind, randomised, non-inferiority trial.

Use of heterologous prime-boost COVID-19 vaccine schedules could facilitate mass COVID-19 immunisation. However, we have previously reported that heterologous schedules incorporating an adenoviral vectored vaccine (ChAdOx1 nCoV-19, AstraZeneca; hereafter referred to as ChAd) and an mRNA vaccine (BNT162b2, Pfizer-BioNTech; hereafter referred to as BNT) at a 4-week interval are more reactogenic than homologous schedules. Here, we report the safety and immunogenicity of heterologous schedules with the ChAd and BNT vaccines. Com-COV is a participant-blinded, randomised, non-inferiority trial evaluating vaccine safety, reactogenicity, and immunogenicity. Adults aged 50 years and older with no or well controlled comorbidities and no previous SARS-CoV-2 infection by laboratory confirmation were eligible and were recruited at eight sites across the UK. The majority of eligible participants were enrolled into the general cohort (28-day or 84-day prime-boost intervals), who were randomly assigned (1:1:1:1:1:1:1:1) to receive ChAd/ChAd, ChAd/BNT, BNT/BNT, or BNT/ChAd, administered at either 28-day or 84-day prime-boost intervals. A small subset of eligible participants (n=100) were enrolled into an immunology cohort, who had additional blood tests to evaluate immune responses; these participants were randomly assigned (1:1:1:1) to the four schedules (28-day interval only). Participants were masked to the vaccine received but not to the prime-boost interval. The primary endpoint was the geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG concentration (measured by ELISA) at 28 days after boost, when comparing ChAd/BNT with ChAd/ChAd, and BNT/ChAd with BNT/BNT. The heterologous schedules were considered non-inferior to the approved homologous schedules if the lower limit of the one-sided 97·5% CI of the GMR of these comparisons was greater than 0·63. The primary analysis was done in the per-protocol population, who were seronegative at baseline. Safety analyses were done among participants receiving at least one dose of a study vaccine. The trial is registered with ISRCTN, 69254139. Between Feb 11 and Feb 26, 2021, 830 participants were enrolled and randomised, including 463 participants with a 28-day prime-boost interval, for whom results are reported here. The mean age of participants was 57·8 years (SD 4·7), with 212 (46%) female participants and 117 (25%) from ethnic minorities. At day 28 post boost, the geometric mean concentration of SARS-CoV-2 anti-spike IgG in ChAd/BNT recipients (12 906 ELU/mL) was non-inferior to that in ChAd/ChAd recipients (1392 ELU/mL), with a GMR of 9·2 (one-sided 97·5% CI 7·5 to ∞). In participants primed with BNT, we did not show non-inferiority of the heterologous schedule (BNT/ChAd, 7133 ELU/mL) against the homologous schedule (BNT/BNT, 14 080 ELU/mL), with a GMR of 0·51 (one-sided 97·5% CI 0·43 to ∞). Four serious adverse events occurred across all groups, none of which were considered to be related to immunisation. Despite the BNT/ChAd regimen not meeting non-inferiority criteria, the SARS-CoV-2 anti-spike IgG concentrations of both heterologous schedules were higher than that of a licensed vaccine schedule (ChAd/ChAd) with proven efficacy against COVID-19 disease and hospitalisation. Along with the higher immunogenicity of ChAd/BNT compared with ChAD/ChAd, these data support flexibility in the use of heterologous prime-boost vaccination using ChAd and BNT COVID-19 vaccines. UK Vaccine Task Force and National Institute for Health Research.

Liu X ，Shaw RH ，Stuart ASV ，Greenland M ，Aley PK ，Andrews NJ ，Cameron JC ，Charlton S ，Clutterbuck EA ，Collins AM ，Dinesh T ，England A ，Faust SN ，Ferreira DM ，Finn A ，Green CA ，Hallis B ，Heath PT ，Hill H ，Lambe T ，Lazarus R ，Libri V ，Long F ，Mujadidi YF ，Plested EL ，Provstgaard-Morys S ，Ramasamy MN ，Ramsay M ，Read RC ，Robinson H ，Singh N ，Turner DPJ ，Turner PJ ，Walker LL ，White R ，Nguyen-Van-Tam JS ，Snape MD ，Com-COV Study Group ... -  《-》

Safety, immunogenicity, and reactogenicity of BNT162b2 and mRNA-1273 COVID-19 vaccines given as fourth-dose boosters following two doses of ChAdOx1 nCoV-19 or BNT162b2 and a third dose of BNT162b2 (COV-BOOST): a multicentre, blinded, phase 2, randomised t

Some high-income countries have deployed fourth doses of COVID-19 vaccines, but the clinical need, effectiveness, timing, and dose of a fourth dose remain uncertain. We aimed to investigate the safety, reactogenicity, and immunogenicity of fourth-dose boosters against COVID-19. The COV-BOOST trial is a multicentre, blinded, phase 2, randomised controlled trial of seven COVID-19 vaccines given as third-dose boosters at 18 sites in the UK. This sub-study enrolled participants who had received BNT162b2 (Pfizer-BioNTech) as their third dose in COV-BOOST and randomly assigned them (1:1) to receive a fourth dose of either BNT162b2 (30 μg in 0·30 mL; full dose) or mRNA-1273 (Moderna; 50 μg in 0·25 mL; half dose) via intramuscular injection into the upper arm. The computer-generated randomisation list was created by the study statisticians with random block sizes of two or four. Participants and all study staff not delivering the vaccines were masked to treatment allocation. The coprimary outcomes were safety and reactogenicity, and immunogenicity (anti-spike protein IgG titres by ELISA and cellular immune response by ELISpot). We compared immunogenicity at 28 days after the third dose versus 14 days after the fourth dose and at day 0 versus day 14 relative to the fourth dose. Safety and reactogenicity were assessed in the per-protocol population, which comprised all participants who received a fourth-dose booster regardless of their SARS-CoV-2 serostatus. Immunogenicity was primarily analysed in a modified intention-to-treat population comprising seronegative participants who had received a fourth-dose booster and had available endpoint data. This trial is registered with ISRCTN, 73765130, and is ongoing. Between Jan 11 and Jan 25, 2022, 166 participants were screened, randomly assigned, and received either full-dose BNT162b2 (n=83) or half-dose mRNA-1273 (n=83) as a fourth dose. The median age of these participants was 70·1 years (IQR 51·6-77·5) and 86 (52%) of 166 participants were female and 80 (48%) were male. The median interval between the third and fourth doses was 208·5 days (IQR 203·3-214·8). Pain was the most common local solicited adverse event and fatigue was the most common systemic solicited adverse event after BNT162b2 or mRNA-1273 booster doses. None of three serious adverse events reported after a fourth dose with BNT162b2 were related to the study vaccine. In the BNT162b2 group, geometric mean anti-spike protein IgG concentration at day 28 after the third dose was 23 325 ELISA laboratory units (ELU)/mL (95% CI 20 030-27 162), which increased to 37 460 ELU/mL (31 996-43 857) at day 14 after the fourth dose, representing a significant fold change (geometric mean 1·59, 95% CI 1·41-1·78). There was a significant increase in geometric mean anti-spike protein IgG concentration from 28 days after the third dose (25 317 ELU/mL, 95% CI 20 996-30 528) to 14 days after a fourth dose of mRNA-1273 (54 936 ELU/mL, 46 826-64 452), with a geometric mean fold change of 2·19 (1·90-2·52). The fold changes in anti-spike protein IgG titres from before (day 0) to after (day 14) the fourth dose were 12·19 (95% CI 10·37-14·32) and 15·90 (12·92-19·58) in the BNT162b2 and mRNA-1273 groups, respectively. T-cell responses were also boosted after the fourth dose (eg, the fold changes for the wild-type variant from before to after the fourth dose were 7·32 [95% CI 3·24-16·54] in the BNT162b2 group and 6·22 [3·90-9·92] in the mRNA-1273 group). Fourth-dose COVID-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose. UK Vaccine Task Force and National Institute for Health Research.

Munro APS ，Feng S ，Janani L ，Cornelius V ，Aley PK ，Babbage G ，Baxter D ，Bula M ，Cathie K ，Chatterjee K ，Dodd K ，Enever Y ，Qureshi E ，Goodman AL ，Green CA ，Harndahl L ，Haughney J ，Hicks A ，van der Klaauw AA ，Kanji N ，Libri V ，Llewelyn MJ ，McGregor AC ，Maallah M ，Minassian AM ，Moore P ，Mughal M ，Mujadidi YF ，Holliday K ，Osanlou O ，Osanlou R ，Owens DR ，Pacurar M ，Palfreeman A ，Pan D ，Rampling T ，Regan K ，Saich S ，Bawa T ，Saralaya D ，Sharma S ，Sheridan R ，Thomson EC ，Todd S ，Twelves C ，Read RC ，Charlton S ，Hallis B ，Ramsay M ，Andrews N ，Lambe T ，Nguyen-Van-Tam JS ，Snape MD ，Liu X ，Faust SN ，COV-BOOST study group ... -  《-》

Heterologous versus homologous COVID-19 booster vaccination in previous recipients of two doses of CoronaVac COVID-19 vaccine in Brazil (RHH-001): a phase 4, non-inferiority, single blind, randomised study.

The inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac, Sinovac) has been widely used in a two-dose schedule. We assessed whether a third dose of the homologous or a different vaccine could boost immune responses. RHH-001 is a phase 4, participant masked, two centre, safety and immunogenicity study of Brazilian adults (18 years and older) in São Paulo or Salvador who had received two doses of CoronaVac 6 months previously. The third heterologous dose was of either a recombinant adenoviral vectored vaccine (Ad26.COV2-S, Janssen), an mRNA vaccine (BNT162b2, Pfizer-BioNTech), or a recombinant adenoviral-vectored ChAdOx1 nCoV-19 vaccine (AZD1222, AstraZeneca), compared with a third homologous dose of CoronaVac. Participants were randomly assigned (5:6:5:5) by a RedCAP computer randomisation system stratified by site, age group (18-60 years or 61 years and over), and day of randomisation, with a block size of 42. The primary outcome was non-inferiority of anti-spike IgG antibodies 28 days after the booster dose in the heterologous boost groups compared with homologous regimen, using a non-inferiority margin for the geometric mean ratio (heterologous vs homologous) of 0·67. Secondary outcomes included neutralising antibody titres at day 28, local and systemic reactogenicity profiles, adverse events, and serious adverse events. This study was registered with Registro Brasileiro de Ensaios Clínicos, number RBR-9nn3scw. Between Aug 16, and Sept 1, 2021, 1240 participants were randomly assigned to one of the four groups, of whom 1239 were vaccinated and 1205 were eligible for inclusion in the primary analysis. Antibody concentrations were low before administration of a booster dose with detectable neutralising antibodies of 20·4% (95% CI 12·8-30·1) in adults aged 18-60 years and 8·9% (4·2-16·2) in adults 61 years or older. From baseline to day 28 after the booster vaccine, all groups had a substantial rise in IgG antibody concentrations: the geometric fold-rise was 77 (95% CI 67-88) for Ad26.COV2-S, 152 (134-173) for BNT162b2, 90 (77-104) for ChAdOx1 nCoV-19, and 12 (11-14) for CoronaVac. All heterologous regimens had anti-spike IgG responses at day 28 that were superior to homologous booster responses: geometric mean ratios (heterologous vs homologous) were 6·7 (95% CI 5·8-7·7) for Ad26.COV2-S, 13·4 (11·6-15·3) for BNT162b2, and 7·0 (6·1-8·1) for ChAdOx1 nCoV-19. All heterologous boost regimens induced high concentrations of pseudovirus neutralising antibodies. At day 28, all groups except for the homologous boost in the older adults reached 100% seropositivity: geometric mean ratios (heterologous vs homologous) were 8·7 (95% CI 5·9-12·9) for Ad26.COV2-S vaccine, 21·5 (14·5-31·9) for BNT162b2, and 10·6 (7·2-15·6) for ChAdOx1 nCoV-19. Live virus neutralising antibodies were also boosted against delta (B.1.617.2) and omicron variants (B.1.1.529). There were five serious adverse events. Three of which were considered possibly related to the vaccine received: one in the BNT162b2 group and two in the Ad26.COV2-S group. All participants recovered and were discharged home. Antibody concentrations were low at 6 months after previous immunisation with two doses of CoronaVac. However, all four vaccines administered as a third dose induced a significant increase in binding and neutralising antibodies, which could improve protection against infection. Heterologous boosting resulted in more robust immune responses than homologous boosting and might enhance protection. Ministry of Health, Brazil.

Costa Clemens SA ，Weckx L ，Clemens R ，Almeida Mendes AV ，Ramos Souza A ，Silveira MBV ，da Guarda SNF ，de Nobrega MM ，de Moraes Pinto MI ，Gonzalez IGS ，Salvador N ，Franco MM ，de Avila Mendonça RN ，Queiroz Oliveira IS ，de Freitas Souza BS ，Fraga M ，Aley P ，Bibi S ，Cantrell L ，Dejnirattisai W ，Liu X ，Mongkolsapaya J ，Supasa P ，Screaton GR ，Lambe T ，Voysey M ，Pollard AJ ，RHH-001 study team ... -  《-》

Immunogenicity and safety in healthy adults of full dose versus half doses of COVID-19 vaccine (ChAdOx1-S or BNT162b2) or full-dose CoronaVac administered as a booster dose after priming with CoronaVac: a randomised, observer-masked, controlled trial in I

Inactivated COVID-19 vaccines effectively prevent death, but their effectiveness for preventing infection or severe illness is known to decrease within 3-6 months following the second priming dose. Here we aimed to evaluate the immunogenicity and safety of three potential booster vaccines administered as a full-dose homologous booster or full-dose or half-dose heterologous boosters among individuals primed with CoronaVac. We did an observer and participant masked, randomised controlled trial study of healthy Indonesian adults from five recruitment sites in Bandung and Jakarta, Indonesia, aged 18 years and older who had previously received two doses of CoronaVac within 3 to less than 6 months or 6 to 9 months before the booster dose. Participants were randomly assigned (1:1:1:1:1) by means of stratified randomisation with random block size to a homologous booster with full-dose CoronaVac or heterologous boosters with ChAdOx1-S or BNT162b2 in full dose or half dose. The primary outcome was to evaluate the seropositive, seroconversion rate, and the geometric mean titres of IgG anti-spike-receptor binding domain and neutralising antibodies, 28 days after booster dose vaccination in the per-protocol population. Safety was assessed as a secondary outcome in all vaccinated booster participants by the incidence rate and intensity of adverse events within 24 h, 7 days, and 28 days after the booster dose. This study is registered with ina-registry.org, INA-GO0HLGB, and is complete. Between Nov 26 and Dec 16, 2021, 1015 people were screened, and 960 healthy adults were enrolled; 190-193 were included in each group. 28 days after receiving the booster, combining the 3 to less than 6 months and 6 to 9 months groups, the proportions of seroconversion rates in each vaccine group were ChAdOx1-S 75 (82%) of 92 to 87 (88%) of 99 for full dose and half dose, BNT162b2 92 (92%) of 100 to 90 (98%) of 92 for full dose and half dose, and CoronaVac in 38 (41%) of 92 to 65 (66%) of 98. All booster groups achieved 100% seropositivity 28 days after the booster dose. Participants in the 6 to 9 months priming group achieved higher titres compared with participants in the 3 to less than 6 months priming group. The geometric mean titres in participants in the 6 to 9 months priming group in each vaccine group were ChAdOx1-S 11258·69 (9562·43-13 255·85) and 7853·04 (6698·92-9206·00) for full dose and half dose, BNT162b2 19999·84 (17 720·58-22 572·25) and 17 017·62 (14 694·40-19 708·16) for full dose and half dose and CoronaVac 1440·55 (1172·81-1769·42) achieved higher titres compared with participants in the 3 to less than 6 months priming group which in each vaccine group were ChAdOx1-S 7730·39 (6401·87-9334·60) and 6684·34 (5678·94-7867·73) for full dose and half dose, BNT162b2 16594·08 (13 993·08-19 678·55) and 12 121·67 (9925·21-14 804·19) for full dose and half dose, and CoronaVac 1210·23 (976·49-1499·92). The median percentage inhibition for the surrogate virus neutralisation test against the delta B.1.617.2 and wild-type (WT) variant before the booster and 28 days after the booster dose was very high in all groups (p<0·001), all with greater than 90% inhibition against both delta and WT strains. No serious adverse events were associated with the vaccines. Within the heterologous booster groups, the adverse event rates in the half-dose groups were lower compared with the full-dose groups. Geometric mean titre values between participants in the 6 to 9 months priming group and the 3 to less than 6 months priming group before the booster dose and between half-dose and full-dose groups 28 days before the booster were not significantly different for half-dose ChAdOx1-S, full-dose BNT162b2, and CoronaVac and were significantly different for full-dose ChAdOx1-S and half-dose BNT162b2. Among individuals primed with CoronaVac, boosting with BNT162b2 (full dose or half dose) or ChAdOx1-S (full dose or half dose) produces substantially better immune responses than in those boosted with CoronaVac. Full-dose and half-dose boosting with either BNT162b2 or ChAdOx1-S produced similar responses. Heterologous booster with half-dose might be considered in adults primed with two doses of CoronaVac vaccine. Ministry of Health, Indonesia. For the Indonesian translation of the abstract see Supplementary Materials section.

Fadlyana E ，Setiabudi D ，Kartasasmita CB ，Putri ND ，Rezeki Hadinegoro S ，Mulholland K ，BCOV21 study group ... -  《-》