Humoral and cellular immune responses to CoronaVac assessed up to one year after vaccination (preprint)

BackgroundThe Sinovac SARS-CoV-2 inactivated vaccine (CoronaVac) has been demonstrated to be safe, well tolerated, and efficacious in preventing mild and severe Covid-19. Although different studies have demonstrated its short-term immunogenicity, long-term cellular and humoral response evaluations are still lacking. MethodsCellular and humoral responses were assessed after enrollment of volunteers in the PROFISCOV phase 3 double-blind, randomized, placebo-controlled clinical trial to evaluate CoronaVac. Assays were performed using flow cytometry to evaluate cellular immune response and an antigen binding electrochemiluminescence assay to detect antigen-specific antibodies to the virus. ResultsFifty-three volunteers were selected for long term assessment of their SARS-CoV-2-specific immune responses. CD4+ T cell responses (including circulating follicular helper (cTfh, CD45RA- CXCR5+) expressing CD40L, as well as non-cTfh cells expressing CXCR3) were observed early upon the first vaccine dose, increased after the second dose, remaining stable for 6-months. Memory CD4+ T cells were detected in almost all vaccinees, the majority being central memory T cells. IgG levels against Wuhan/WH04/2020 N, S and receptor binding domain (RBD) antigens and the variants of concern (VOCs, including B.1.1.7/Alpha, B.1.351/Beta and P.1/Gamma) S and RBD antigens peaked 14 days after the second vaccine shot, and were mostly stable for a 1-year period. ConclusionsCoronaVac two-doses regimen is able to induce a potent and durable SARS-CoV-2 specific cellular response. The cellular reaction is part of a coordinated immune response that includes high levels of specific IgG levels against parental and SARS-CoV-2 VOC strains, still detected after one year. FundingFundacao Butantan, Instituto Butantan and Sao Paulo Research Foundation (FAPESP) (grants 2020/10127-1 and 2020/06409-1). This work has also been supported by NIH contract 75N93019C00065 (A.S, D.W). PATH facilitated reagent donations for this work with support by the Bill & Melinda Gates Foundation (INV-021239). Under the grant conditions of the foundation, a Creative Commons Attribution 4.0 generic License has already been assigned to the Author Accepted Manuscript version that might arise from this submission.

Safety and Immunogenicity of CoronaVac in People Living with HIV (preprint)

Background: People living with HIV (PLWH) may have a poor or delayed response to vaccines, mainly when CD4+ T cell counts are low. There are limited data concerning the safety and immunogenicity of COVID-19 vaccines in PLWH.Methods: This prospective controlled study evaluated the safety and immunogenicity of the SARS-CoV-2 inactivated vaccine CoronaVac in PLWH compared with controls with no known immunosuppression. Immunogenicity was assessed with SARS-CoV-2 IgG seroconversion (SC), neutralizing antibodies (NAb) activity, and factor increase in IgG geometric mean titers (FI-GMT). We also investigated if levels of CD4+ T cell counts (< or ≥500 cells/mm3) were associated with CoronaVac immunogenicity.Findings: 511 participants (215 PLWH and 296 controls) were eligible for the immunogenicity analysis. At vaccine completion (D69), although the percentage of participants with SC and NAb positivity was high for both PLWH and controls, it was somewhat lower in PLWH. CD4+ T cell was identified as a relevant factor for immunogenicity, with lower SC and NAb positivity in PLWH with CD4+ counts <500 cells/mm3 compared to those with ≥500 cells/mm3. In a multivariable logistic regression model for NAb positivity after a complete two-dose regimen adjusted for age and sex, compared with PLWH with a CD4+ T cell count <500/mm3, those with CD4+ counts ≥500/mm3 had 2·26 times the odds of having positivity in NAb activity (95% CI 1·18-4·32; p=0·014), whereas controls had 3·21 times the odds of this outcome. No serious adverse reactions were reported during the study.Interpretation: Immunogenicity following CoronaVac in PLWH seems robust but reduced compared with controls; PLWH with CD4+ counts <500/mm 3 are at increased risk for a blunted antibody response following vaccination.Funding: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); and B3 - Bolsa de Valores do Brasil.Declaration of Interest: EGK is the Principal Investigator for the CoronaVac phase 3 clinical trial at University of Sao Paulo. VIAS is the Principal Investigator for the Janssen COVID-19 vaccine phase 3 clinical trial at University of Sao Paulo. INCOMPLETE, MISSING SOME AUTHORS FROM DOIEthical Approval: The national and local ethics committees approved the study.

Clinical Characteristics of COVID-19 by SARS-CoV-2 Gamma Variant in Vaccinated and Non-Vaccinated Healthcare Workers (preprint)

Background: The Gamma variant has been considered the predominant SARS-CoV-2 lineage in Brazil during the first half of 2021. We aimed to characterise the clinical presentation of COVID-19 caused by the Gamma variant in comparison with strains that are not variants of concern (non-VoC).Method: We performed a prospective cohort study including symptomatic COVID-19 cases among healthcare workers from January 22 to May 15, 2021. Positive samples for SARS-CoV-2 RT-PCR underwent whole genome sequencing. COVID-19 symptoms, caused by the Gamma variant or non-VoC, and risk factors for Gamma variant infection were evaluated using multiple logistic regression analyses.Findings: We included 423 COVID-19 cases, of which 415 (98%) with mild disease. One hundred and seventy-five (41%) patients had been fully immunised, of which 173/175 (99%) had received CoronaVac. There were 313 (74%) Gamma variant cases and 110 (26%) non-VoC cases. Hyposmia/anosmia and dysgeusia were present in 129 (30%) and 108 (26%) of cases, respectively. Lower frequencies of hyposmia/anosmia (OR=0.304, p <0.001) and dysgeusia (OR=0.385, p =0.011) were the only symptoms significantly associated with Gamma variant infection. COVID-19 immunisation, previous COVID-19 and age were not associated with Gamma variant infection.Interpretation: The increase in Gamma variant cases should raise the awareness that COVID-19 may present more often with cold-like symptoms because of a decreased frequency of hyposmia/anosmia and dysgeusia.Funding: Supported by the Itau Unibanco “Todos pela saúde” program”.Declaration of Interest: None to declare. Ethical Approval: This study was approved by the Hospital’s Ethics Committee (CAAE: 42708721.0.0000.0068).

Dynamics of Inactivated SARS-CoV-2 Vaccine Antibody Response in SARS-CoV-2-Seropositive Autoimmune Rheumatic Disease Patients (preprint)

Background: Limited information is available on response to Covid-19 vaccines in autoimmune rheumatic disease patients(ARD) previously exposed to the SARS-CoV-2. We compared the dynamics of vaccine induced antibody production after immunization with CoronaVac in SARS-CoV-2 - seropositive ARD patients(ARD+) with two age/sex balanced groups: SARS-CoV-2 naïve ARD patients(NAÏVE-ARD) and SARS-CoV-2-seropositive control group(CTRL+).Methods: Participants of this phase 4 prospective controlled study were vaccinated with two doses of CoronaVac(28-days interval). Primary objective was immunogenicity dynamics evaluated by median neutralizing activity(NAb-activity)/anti-SARS-Cov-2 ln(IgG) titers[ln(IgG)] from D0-D28 and from D28-D69. Secondary objectives included safety and other immunogenicity parameters.Findings: Disease and therapy were similar in ARD+ and NAÏVE-ARD groups(p>0·05). A comparable dynamics was observed for ARD+ and CTRL+ with a plateau increase occurring from D0-D28[ARD+, NAb-activity:59·1% to 81·8%, mean difference -12·1%,p=0·002 and anti-S1/S2-GMT:52·3 to 128·9, ln(IgG) mean difference -0·9,p<0·001] and [CTRL+, NAb-activity:57·5 to 91·9%, mean difference -25·2%,p<0·001 and anti-S1/S2-GMT: 53·3 to 202·0, ln(IgG) mean difference -1·33,p<0·001]. Insignificant increments occurred from D28-D69 for ARD+ and CTRL+ regarding NAb-activity(p>0·999) and anti-S1/S2-GMT(p<0·999). In contrast, a distinct pattern was observed for NAÏVE-ARD with negligible increase from D0-D28 [NAÏVE-ARD: NAb-activity:15 vs. 15%, mean difference -8·3%,p<0·001 and anti-S1/S2-GMT:2·3 vs. 5·7, ln(IgG) mean difference -0·93,p<0·001] and a moderate increase from D28-D69[NAÏVE-ARD: NAb-activity:15·0 vs. 39·4%, mean difference -19·2%,p<0·001 and anti-S1/S2-GMT:5·7 vs. 29·6, ln(IgG) mean difference -1·65,p<0·001]. Supporting these findings, significant differences in NAb activity/ln(IgG) anti-S1/S2-GMT were observed between ARD+ vs. NAÏVE-ARD at D0:43·8%/3·14,p<0·001, D28:47·5%/3·12,p<0·001 and D69:29%/1·53,p<0·001, whereas no difference occurred between ARD+ vs. CTRL+ at D0:-0·5%/-0·02,p>0·999 and D69:-12·3%,p=0·167/0·32%,p=0·258 with minor difference at D28:-13·6%, p=0·067/-0·45,p=0·006.Interpretation: ARD+ patients mount a robust plateau response after a single dose of inactivated SARS-CoV-2 vaccine, independent of pre-existing ARD/therapy, whereas NAÏVE-ARD patients require the second dose to ensure a moderate antibody production. Our findings raise the possibility of a single dose regimen in ARD patients previously exposed to SARS-CoV-2.[clinicaltrials.gov#NCT04754698]Funding: FAPESP/CNPq/B3-Bolsa de Valores-Brasil.Declaration of Interest: The authors declare no competing interests.Ethical Approval: The protocol was approved by the National and Institutional Ethical Committee (CAAE: 42566621.0.0000.0068)

Efficacy and Safety of a COVID-19 Inactivated Vaccine in Healthcare Professionals in Brazil: The PROFISCOV Study (preprint)

Background: Vaccines are urgently needed to tackle the unprecedented morbidity and mortality of COVID-19. Administration of inactivated viruses are the common and mature platform of developing new vaccines. CoronaVac is an inactivated vaccine that has undergone preclinical tests and phase I/II clinical trials.Methods: We conducted a randomised, double-blind, placebo-controlled phase 3 clinical trial with CoronaVac among healthy healthcare professionals in 16 centres in Brazil. Participants received two doses of vaccine (3 μg in 0.5 mL) vaccine or placebo at day 0 and 14. The primary efficacy endpoint was the number of symptomatic COVID-19 cases confirmed by RT-PCR 14 days after the second dose of the vaccine. Prevention of disease severity was a major secondary efficacy endpoint, and adverse events incidence up to seven days after immunization was the primary safety outcome. The trial was registered at ClinicalTrials.gov, NCT04456595.Findings: Between July 21 and Dec 16, 2020, 12 396 participants were enrolled and received at least one vaccine or placebo dose. There were 9,823 participants who received the two doses and were followed for at least 14 days and had, therefore, reached the final efficacy analysis. There were 253 confirmed COVID-19 cases in the cohort: 85 cases (11.0/100 person-year) among 4,953 participants in the vaccine group, and 168 cases (22·3/100 person-year) among 4,870 participants in the placebo group. The primary efficacy against symptomatic COVID-19 was 50·7% (95%CI 36·0-62·0). The secondary efficacy against cases requiring assistance (score ≥3) and moderate and severe cases (score ≥4) were 83·7% (95%CI 58·0-93.7) and 100% (95%CI 56·4-100.0) respectively. All 6 cases of severe COVID-19 occurred in the placebo group. The incidence of adverse reactions, which was mainly pain at the administration site, was higher in the vaccine group (77·1%) than in the placebo group (66·4%). There were 67 serious adverse events reported by 64 participants and all were determined to be unrelated to vaccination, including two fatal cases. In a subset of participants, neutralizing antibody assays showed similar seroconversion and geometric mean titres against B.1.128, P.1, and P.2 variants.Interpretation: A phase 3 clinical trial conducted in healthcare professionals in Brazil demonstrated that the inactivated CoronaVac vaccine has a good safety profile and is efficacious against any symptomatic SARS-CoV-2 infections and highly protective against moderate and severe COVID-19.

EVALUATION OF ELEVEN IMMUNOCHROMATOGRAPHIC ASSAYS FOR SARS-CoV-2 DETECTION: INVESTIGATING DENGUE CROSS-REACTION (preprint)

Background: COVID-19 disease (Coronavirus disease 2019) caused by SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) is widespread worldwide, affecting more than 11 million people globally (July 6th, 2020). Diagnostic techniques have been studied in order to contain the pandemic. Immunochromatographic (IC) assays are feasible and low cost alternative for monitoring the spread of COVID-19 in the population. Methods: Here we evaluate the sensitivity and specificity of eleven different immunochromatografic tests in 98 serum samples from confirmed cases of COVID-19 through RT-PCR and 100 negative serum samples from blood donors collected in February 2019. Considering the endemic situation of Dengue in Brazil, we also evaluated the cross-reactivity with Dengue using 20 serum samples from patients with confirmed diagnosis for Dengue collected in early 2019 through four different tests. Results: Our results demonstrated agreement between immunochromatographic assays and RT-PCR, especially after 10 days since the onset of symptoms. The evaluation of IgG and IgM antibodies combined demonstrated a strong level of agreement (0.85) of IC assays and RT-PCR. It was observed cross-reactivity between Dengue and COVID-19 using four different IC assays for COVID-19 diagnosis. The specificity of IC assays to detected COVID-19 IgM antibodies using Dengue serum samples varied from 80% to 85%; the specificity of IgG detection was 100% and total antibody was 95%. Conclusions: We found high sensitivity, specificity and good agreement of IC assays, especially after 10 days onset of symptoms. However, we detected cross-reactivity between Dengue and COVID-19 mainly with IgM antibodies demonstrating the need for better studies about diagnostic techniques for these diseases.