Longitudinal study comparing IgG antibodies induced by heterologous prime-boost COVID-19 vaccine.

Vaccines are critical cost-effective tools to control the COVID-19 pandemic. The heterologous prime-boost vaccination has been used by many countries to overcome supply issues, so the effectiveness and safety of this strategy need to be better clarified. This study aims to verify the effect of heterologous prime-boost COVID-19 vaccination on healthcare professionals from Dante Pazzanese Hospital in Brazil. It was performed serological assays of vaccinated individuals after 2-dose of CoronaVac (Sinovac; n = 89) or ChAdOx1 nCoV-19 (Oxford-AstraZeneca; n = 166) followed by a BNT162b2 booster (Pfizer-BioNTech; n = 255). The serum antibodies anti-S (spike), anti-N (nucleocapsid), and anti-RBD (receptor binding domain) were assessed by enzyme-linked immunosorbent assay. The heterologous booster dose induced a 10-fold higher anti-Spike antibody regardless of the 2-dose of a prime vaccine. It was strikingly observed that BNT162b2 enhanced levels of anti-spike antibodies, even in those individuals who did not previously respond to the 2-dose of CoronaVac. In conclusion, the heterologous scheme of vaccination using mRNA as a booster vaccine efficiently enhanced the antibody response against SARS-CoV-2, especially benefiting those elderly who were seronegative with a virus-inactivated vaccine.

Serological Testing for COVID-19, Immunological Surveillance, and Exploration of Protective Antibodies.

Serological testing is a powerful tool in epidemiological studies for understanding viral circulation and assessing the effectiveness of virus control measures, as is the case of SARS-CoV-2, the pathogenic agent of COVID-19. Immunoassays can quantitatively reveal the concentration of antiviral antibodies. The assessment of antiviral antibody titers may provide information on virus exposure, and changes in IgG levels are also indicative of a reduction in viral circulation. In this work, we describe a serological study for the evaluation of antiviral IgG and IgM antibodies and their correlation with antiviral activity. The serological assay for IgG detection used two SARS-CoV-2 proteins as antigens, the nucleocapsid N protein and the 3CL protease. Cross-reactivity tests in animals have shown high selectivity for detection of antiviral antibodies, using both the N and 3CL antigens. Using samples of human serum from individuals previously diagnosed by PCR for COVID-19, we observed high sensitivity of the ELISA assay. Serological results with human samples also suggest that the combination of higher titers of antiviral IgG antibodies to different antigen targets may be associated with greater neutralization activity, which can be enhanced in the presence of antiviral IgM antibodies.

COVID-19 in heart transplant patients: Case reports from Brazil.

INTRODUCTION: The COVID-19 pandemic continues, with a late hyperinflammatory phase. The immunosuppressive therapy used in heart transplant patients, in theory, could reduce inflammation, thus benefitting patients with COVID-19. So far, however, there is still very little literature on this subject. METHODS: This is a single-center retrospective study. We described laboratory parameters and clinical outcomes from 11 heart transplant patients with COVID-19 assisted at Dante Pazzanese Institute of Cardiology between March and July 2020. RESULTS: Patients with ages of between 35 and 79 years were enrolled, and heart transplantation ranged from 3 to 264 months. The main comorbidities were diabetes mellitus (9/11; 81.8%), hypertension (10/11; 90.9%), and chronic renal disease (6/11; 54.5%). Cyclosporine A was used in 10 (90.9%) patients, mycophenolate mofetil in 9 (81.8%) patients, and mTOR inhibitor in 5 (45.5%) patients. Fever and cough were observed in 8 (72.7%) patients, and dyspnea and gastrointestinal symptoms in 5 (45.5%) patients. Lymphopenia was observed in 10 (90.9%) patients and thrombocytopenia in 5 (45.5%) patients. The higher level of troponin associated with chest tomography above 50% of bilateral pulmonary infiltrates with ground-glass opacity (GGO) was observed in those with the worst outcomes. Nine patients needed intensive care, and hospital stay ranged from 4 to 21 days, with 2 (18.2%) patients requiring vasopressor drugs and mechanical ventilation, and three (27.3%) patients dying due to COVID-19 complications. CONCLUSION: Heart transplant patients had similar symptoms and outcomes as the general population; immunosuppressive therapy seems not to have protected them. Patients who presented higher levels of troponin and D-dimer, associated with greater GGO pulmonary infiltrates, had worse outcomes. More studies with larger cohorts may clarify immunosuppressive effects on COVID-19 outcomes.