BBIBP-CorV (Sinopharm) vaccination- induced immunity is affected by age, gender and prior COVID-19 and activates responses to spike and other antigens

Long-term solutions against SARS-CoV-2 infections require understanding of immune protection induced by different vaccine COVID-19 formulations. We investigated humoral and cellular immunity induced by Sinopharm (BBIBP-CorV) in a region of high SARS-CoV-2 seroprevalence. Levels of IgG antibodies to SARS-CoV-2 spike protein and its receptor-binding domain (RBD) were determined 24-weeks. Cellular immunity was investigated using a commercially available IFN-{gamma} release assay to SARS-CoV-2 spike (Ag1 and 2) and extended genome antigens (Ag3). Increasing IgG seropositivity to Spike protein and RBD was observed post-vaccination. Seropositivity was reduced in those over 50 years and raised in females and those with prior COVID-19. After 20 weeks post-vaccination, only one third of participants had positive T cell responses to SARS-CoV-2 antigens. Prior COVID-19 impacted IFN{gamma} responses, with reactivity enhanced in those infected earlier. The frequency of IFN{gamma} responses was highest to extended genome antigen set. Overall, BBIBP-CorV- induced antibody responses were impacted by age, gender and prior COVID-19. Cellular immunity was present in a limited number of individuals after 20 weeks but was enhanced by prior infection. This suggests the need for booster vaccinations in older individuals. BBIBP-CorV-induced cellular activation is broader than to spike, requiring further study to understand how to monitor vaccine effectiveness.

Risk factors for infection, predictors of severe disease and antibody response to COVID-19 in patients with rheumatic diseases in Portugal - a multicentre, nationwide study

In order to identify risk factors for SARS-CoV-2 infection as well as for severe/critical COVID-19 in rheumatic and musculoskeletal diseases (RMDs) patients, we conducted a multicentre observational nationwide study of adult patients prospectively-followed in the Rheumatic Diseases Portuguese Register - Reuma.pt - during the first 6 months of the pandemic. We further evaluated the development of IgG antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 in patients with RMDs. We used multivariate logistic regression to compare patients with COVID-19 (COVID-19+) with those who did not develop the disease (COVID-19-) and patients with mild/moderate disease with those exhibiting severe/critical COVID-19. COVID-19+ patients were asked to collect a blood sample for IgG testing [≥] 3 months after infection and results were compared with age-, sex- and sampling date-matched controls. Overall, 179 cases of COVID-19 were registered in Reuma.pt in the period of interest (median age 55 (IQR 20); 76.5% females) in a total of 6404 registered appointments. We found that patients treated with TNF inhibitors had reduced odds of infection (OR=0.16, 95%CI 0.10-0.26, p<0.001), severe disease (OR 0.11, 95%CI 0.01-0.84, p=0.010) and seroconversion rates (OR 0.13, 95%CI 0.02-0.91, p=0.040). Tocilizumab was also associated with a reduced risk of COVID-19 (OR 0.15, 95%CI 0.05-0.41, p<0.001). Older age, major comorbidities (diabetes, hypertension, obesity, cardiovascular disease, chronic pulmonary and kidney disease) and rituximab were associated with an increased risk of infection and worse prognosis, in line with previous reports. Importantly, most patients with inflammatory RMDs (86.2%) were able to develop a robust antibody response after SARS-CoV-2 infection, which was linked with disease severity.

Controlling the pandemic during the SARS-CoV-2 vaccination rollout: a modeling study

There is a consensus that mass vaccination against SARS-CoV-2 will ultimately end the COVID-19 pandemic. However, it is not clear when and which control measures can be relaxed during the rollout of vaccination programmes. We investigate relaxation scenarios using an age-structured transmission model that has been fitted to age-specific seroprevalence data, hospital admissions, and projected vaccination coverage for Portugal. Our analyses suggest that the pressing need to restart socioeconomic activities could lead to new pandemic waves, and that substantial control efforts prove necessary throughout 2021. Using knowledge on control measures introduced in 2020, we anticipate that relaxing measures completely or to the extent as in autumn 2020 could launch a wave starting in April 2021. Additional waves could be prevented altogether if measures are relaxed as in summer 2020 or in a step-wise manner throughout 2021. We discuss at which point control of COVID-19 would be achieved for each scenario.

Seroprevalence of anti-SARS-CoV-2 antibodies in COVID-19 patients and healthy volunteers

SARS-CoV-2 has emerged as a novel human pathogen, causing clinical signs, from fever to pneumonia - COVID-19 - but may remain mild or even asymptomatic. To understand the continuing spread of the virus, to detect those who are and were infected, and to follow the immune response longitudinally, reliable and robust assays for SARS-CoV-2 detection and immunological monitoring are needed and have been setup around the world. We quantified immunoglobulin M (IgM), IgG and IgA antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) or the Spike (S) protein over a period of five months following COVID-19 disease onset or in previously SARS-CoV-2 PCR-positive volunteers. We report the detailed setup to monitor the humoral immune response from over 300 COVID-19 hospital patients and healthcare workers, 2500 University staff and 187 post-COVID19 volunteers, and assessing titres for IgM, IgG and IgA. Anti-SARS-CoV-2 antibody responses followed a classic pattern with a rapid increase within the first three weeks after symptoms. Although titres reduce from approximately four weeks, the ability to detect SARS-CoV-2 antibodies remained robust for five months in a large proportion of previously virus-positive screened subjects. Our work provides detailed information for the assays used, facilitating further and longitudinal analysis of protective immunity to SARS-CoV-2. Moreover, it highlights a continued level of circulating neutralising antibodies in most people with confirmed SARS-CoV-2, at least up to five months after infection.