Absence of Anti-RBD Antibodies in SARS-CoV-2 Infected or Naive Individuals Prior to Vaccination with CoronaVac Leads to Short Protection of Only Four Months Duration.

The COVID-19 pandemic is the biggest public health threat facing the world today. Multiple vaccines have been approved; however, the emergence of viral variants such as the recent Omicron raises the possibility of booster doses to achieve adequate protection. In Brazil, the CoronaVac (Sinovac, Beijing, China) vaccine was used; however, it is important to assess the immune response to this vaccine over time. This study aimed to monitor the anti-SARS-CoV-2 antibody responses in those immunized with CoronaVac and SARS-CoV-2 infected individuals. Samples were collected between August 2020 and August 2021. Within the vaccinated cohort, some individuals had a history of infection by SARS-CoV-2 prior to immunization, while others did not. We analyzed RBD-specific and neutralizing-antibodies. Anti-RBD antibodies were detected in both cohorts, with a peak between 45-90 days post infection or vaccination, followed by a steady decline over time. In those with a previous history of COVID-19, a higher, longer, more persistent response was observed. This trend was mirrored in the neutralization assays, where infection, followed by immunization, resulted in higher, longer lasting responses which were conditioned on the presence of levels of RBD antibodies right before the vaccination. This supports the necessity of booster doses of CoronaVac in due course to prevent serious disease.

Atypical hand-foot-mouth disease in Belém, Amazon region, northern Brazil, with detection of coxsackievirus A6.

BACKGROUND: Enterovirus (EV) A71 and coxsackievirus (CV) A16 were the most frequent serotypes involved in hand, foot, and mouth disease (HFMD) outbreaks throughout Asia. In the past 5 years, however, CV-A6 has emerged as a new important pathogen worldwide, and more severe and extensive dermatologic presentations has been reported. OBJECTIVES: Identify the clinical spectrum for atypical HFMD and enterovirus serotypes in Belém, Pará, Amazon region of northern Brazil. STUDY DESIGN: A prospective ambulatory clinic-based surveillance conducted from January to June 2019, involving patients under 15 years with symptoms of HFMD. Stool, serum, oropharyngeal, and skin swab samples were analyzed. Real-time RT-PCR was performed to detect the viral genome of enteroviruses. Positive specimens were submitted to semi-nested PCR. Physical examinations and demographic data were recorded on a standardized form. RESULTS: 48 patients with symptoms of HFMD were included in the study and collected all samples according to protocol. Enteroviruses were detected in 83 % of patients. An atypical form of HFMD with vesiculobullous exanthema was present in 70 % (28/40); desquamation of the palms and soles detected in 90 % (36/40) and onychomadesis in 30 % (12/40) of patients. The serotype was identified in 22 patients, CV- A6 occurred in 81.8 % of them. CONCLUSION: This is the first ambulatory surveillance and virologic investigation involving HFMD performed in outpatients from Amazon region, Brazil. The detection of CV-A6 was related to atypical forms HFMD. Desquamation of the palms and soles and nail changes occurred with frequency, such as a late sequel in the HFMD disease.

Re-emergence of a coxsackievirus A24 variant causing acute hemorrhagic conjunctivitis in Brazil from 2017 to 2018.

A large outbreak (over 200,000 cases) of acute hemorrhagic conjunctivitis (AHC) took place in Brazil during the summer of 2017/2018, seven years after a nationwide epidemic, which occurred in 2011. To identify the etiological agent, 80 conjunctival swabs from patients with a clinical presentation suggestive of AHC were analyzed at the national enterovirus laboratory. Real-time RT-PCR for human enteroviruses was performed, and enterovirus RNA was detected in 91.25% (73/80) of the specimens. Twenty-nine swab fluids were used to inoculate cell cultures (RD and Hep2C), and 72.4% (21/29) yielded a cytopathic effect. Genotype IV coxsackievirus A24v (CV-A24v) was identified as the causative agent of the outbreak. Phylogenetic analysis based on the VP1 gene revealed that Brazilian isolates were genetically related to strains that caused an outbreak in French Guiana in 2017. Our results show the re-emergence of CV-A24v causing AHC outbreaks in Brazil between the end of 2017 and the beginning of 2018.

Synthesis and characterization of the nitrides of platinum and iridium.

Transition metal nitrides are of great technological and fundamental importance because of their strength and durability and because of their useful optical, electronic, and magnetic properties. We have evaluated a recently synthesized platinum nitride (PtN) that was shown to have a large bulk modulus, and we propose a structure that is isostructural with pyrite and has the stoichiometry PtN2. We have also synthesized a recoverable nitride of iridium under nearly the same conditions of pressure and temperature as PtN2. Although it has the same stoichiometry, it exhibits much lower structural symmetry. Preliminary results suggest that the bulk modulus of this material is also very large.