Generation of neutralizing antibodies against Omicron, Gamma and Delta SARS-CoV-2 variants following CoronaVac vaccination

Vaccination is a fundamental tool to prevent SARS-CoV-2 infection and to limit the COVID-19 pandemic. The emergence of SARS-CoV-2 variants with multiple mutations has raised serious concerns about the ability of neutralizing antibody responses elicited by prior vaccination to effectively combat these variants. The neutralizing capacity against the Gamma, Delta and Omicron variants of sera from individuals immunized with the CoronaVac vaccine remains incompletely determined. The present study evaluated 41 health care workers at the Faculdade de Medicina of the Universidade de Sao Paulo, in Sao Paulo, Brazil, naive to previous SARS- CoV-2 infection, who were vaccinated with two doses of the CoronaVac SARS-CoV-2 vaccine 28 days apart. Neutralizing antibody levels against the Gamma, Delta, and Omicron variants were measured at 32 and 186 days after the second vaccination. We also measured neutralizing antibodies against Omicron in 34 of these individuals following a subsequent booster immunization with the Pfizer vaccine. Quantification of neutralizing antibodies was performed using the Cytopathic Effect-based Virus Neutralization test. Neutralization antibody activity against the Gamma, Delta and Omicron variants was observed in 78.0%, 65.9% and 58.5% of serum samples, respectively, obtained at a mean of 32 days after the second immunization. This decreased to 17.1%, 24.4% and 2.4% of sera having activity against Delta, Gamma and Omicron, respectively, at 186 days post-vaccination. The median neutralizing antibody titers at 32 days were 1:40, 1:20 and 1:20 against Gamma, Delta and Omicron, respectively, and decreased to an undetectable median level against all variants at the later time. A booster immunization with the Pfizer vaccine elicited neutralizing antibodies against Omicron in 85% of subjects tested 60 days after vaccination. We conclude that two doses of the CoronaVac vaccine results in limited protection of short duration against the Gamma, Delta and Omicron SARS-CoV-2 variants. A booster dose with the Pfizer vaccine induced antibody neutralizing activity against Omicron in most patients which was measurable 60 days after the booster

Absence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variant

Objectives: The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. Methods: Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. Results: Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively. Conclusions: Neutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant

SARS-CoV-2 shedding, infectivity, and evolution in an immunocompromised adult patient

This study aimed to provide further insight into the evolutionary dynamics of SARS-CoV-2 by analyzing the case of a 40-year-old man who had previously undergone autologous hematopoietic stem cell transplantation due to a diffuse large B-cell lymphoma. He developed a persistent SARS-CoV-2 infection lasting at least 218 days and did not manifest a humoral immune response to the virus during this follow-up period. Whole-genome sequencing and viral cultures confirmed a persistent infection with a replication-positive virus that had undergone genetic variation for at least 196 days after symptom onset

Characterization of Dengue Virus Type 2: New Insights on the 2010 Brazilian Epidemic

Dengue viruses (DENV) serotypes 1, 2, and 3 have been causing yearly outbreaks in Brazil. In this study, we report the re-introduction of DENV2 in the coast of São Paulo State. Partial envelope viral genes were sequenced from eighteen patients with dengue fever during the 2010 epidemic. Phylogenetic analysis showed this strain belongs to the American/Asian genotype and was closely related to the virus that circulated in Rio de Janeiro in 2007 and 2008. The phylogeny also showed no clustering by clinical presentation, suggesting that the disease severity could not be explained by distinct variants or genotypes. The time of the most recent common ancestor of American/Asian genotype and the São Paulo and Rio de Janeiro (SP/RJ) monophyletic cluster was estimated to be around 40 and 10 years, respectively. Since this virus was first identified in Brazil in 2007, we suggest that it was already circulating in the country before causing the first documented outbreak. This is the first description of the 2010 outbreak in the State of São Paulo, Brazil, and should contribute to efforts to control and monitor the spread of DENVs in endemic areas

Neutralizing antibodies against the SARS-CoV-2 Omicron variant following two CoronaVac vaccinations and a Pfizer/BioNTech mRNA vaccine booster

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Are mobile phones part of the chain of transmission of SARS-CoV-2 in hospital settings?

Mobile phones (MPs) have become an important work tool around the world including in hospitals. We evaluated whether SARS-CoV-2 can remain on the surface of MPs of first-line healthcare workers (HCW) and also the knowledge of HCWs about SARS-CoV-2 cross-transmission and conceptions on the virus survival on the MPs of HCWs. A cross-sectional study was conducted in the COVID-19 Intensive Care Unit of a teaching hospital. An educational campaign was carried out on cross-transmission of SARS-CoV-2, and its permanence in fomites, in addition to the proper use and disinfection of MPs. Herewith an electronic questionnaire was applied including queried conceptions about hand hygiene and care with MP before and after the pandemic. The MPs were swabbed with a nylon FLOQ Swab™, in an attempt to increase the recovery of SARS-CoV-2. All MP swab samples were subjected to SARS-CoV-2 RT-PCR; RT-PCR positive samples were subjected to viral culture in Vero cells (ATCC® CCL-81™). Fifty-one MPs were swabbed and a questionnaire on hand hygiene and the use and disinfection of MP was applied after an educational campaign. Most HCWs increased adherence to hand hygiene and MP disinfection during the pandemic. Fifty-one MP swabs were collected and two were positive by RT-PCR (4%), with Cycle threshold (Ct ) values of 34-36, however, the cultures of these samples were negative. Although most HCWs believed in the importance of cross-transmission and increased adherence to hand hygiene and disinfection of MP during the pandemic, SARS-CoV-2 RNA was detected in MPs. Our results suggest the need for a universal policy in infection control guidelines on how to care for electronic devices in hospital settings

CD8+ T Lymphocyte Expansion, Proliferation and Activation in Dengue Fever

<div><p>Dengue fever induces a robust immune response, including massive T cell activation. The level of T cell activation may, however, be associated with more severe disease. In this study, we explored the level of CD8+ T lymphocyte activation in the first six days after onset of symptoms during a DENV2 outbreak in early 2010 on the coast of São Paulo State, Brazil. Using flow cytometry we detected a progressive increase in the percentage of CD8+ T cells in 74 dengue fever cases. Peripheral blood mononuclear cells from 30 cases were thawed and evaluated using expanded phenotyping. The expansion of the CD8+ T cells was coupled with increased Ki67 expression. Cell activation was observed later in the course of disease, as determined by the expression of the activation markers CD38 and HLA-DR. This increased CD8+ T lymphocyte activation was observed in all memory subsets, but was more pronounced in the effector memory subset, as defined by higher CD38 expression. Our results show that most CD8+ T cell subsets are expanded during DENV2 infection and that the effector memory subset is the predominantly affected sub population.</p></div

Shotgun metagenomic sequencing of the first case of monkeypox virus in Brazil, 2022

Monkeypox virus (MPXV), a zoonotic virus endemic to the African continent, has been reported in 33 non-endemic countries since May 2022. We report an almost complete genome of the first confirmed case of MPXV in Brazil. Shotgun metagenomic sequencing was completed in 18 hours, from DNA extraction to consensus sequence generation

CD8+ T lymphocytes in the course of dengue fever.

<p>(A) Percentage within T cells and (B) absolute numbers of CD8+ T lymphocytes in the peripheral blood from healthy controls (n = 17) and dengue fever patients at different days of symptoms (n = 74). A significant change in the percentage of CD8+ T lymphocytes was observed, between days 5 and 6 after the onset of symptoms when compared to healthy controls and days 3 and 4 of symptoms, as shown in A. However, decreased absolute CD8+ T lymphocyte numbers were documented in the first four days of symptoms when compared to healthy controls, returning to higher levels later in the disease’s course, as shown in B. *p< 0.05, ** p<0.01.</p