Neutralizing antibody response after immunization with a COVID-19 bivalent vaccine: Insights to the future.

The raising of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants led to the use of COVID-19 bivalent vaccines, which include antigens of the wild-type (WT) virus, and of the Omicron strain. In this study, we aimed to evaluate the impact of bivalent vaccination on the neutralizing antibody (NAb) response. We enrolled 93 volunteers who had received three or four doses of monovalent vaccines based on the original virus (n = 61), or a booster shot with the bivalent vaccine (n = 32). Serum samples collected from volunteers were subjected to neutralization assays using the WT SARS-CoV-2, and Omicron subvariants. In addition, immunoinformatics to quantify and localize highly conserved NAb epitopes were performed. As main result, we observed that the neutralization titers of samples from individuals vaccinated with the bivalent vaccine were higher for the original virus, in comparison to their capacity of neutralizing the Omicron variant and its subvariants. NAb that recognize epitopes mostly conserved in the WT SARS-CoV-2 were boosted, while those that recognize epitopes mostly present in the Omicron variant, and subvariants were primed. These results indicate that formulation of future vaccines shall consider to target present viruses, and not viruses that no longer circulate.

Co-circulation of Chikungunya virus, Zika virus, and serotype 1 of Dengue virus in Western Bahia, Brazil.

Chikungunya, mayaro, dengue, zika, and yellow fever are mosquito-borne viral diseases caused, respectively, by Chikungunya virus, Mayaro virus (CHIKV and MAYV, respectively: Togaviridae: Alphavirus), Dengue virus, Zika virus, and Yellow fever virus (DENV, ZIKV, and YFV, respectively: Flaviviridae: Flavivirus). These viruses have an important epidemiological impact worldwide, especially in Brazil. Western Bahia is one of the less studied regions in that country regarding the circulation of these pathogens. In this study, we aimed to apply molecular biology assays to better know the mosquito-borne viruses circulating in Barreiras and Luís Eduardo Magalhães, two main cities of Western Bahia. From March to June 2021, we enrolled 98 patients with the clinical diagnosis of dengue. Personal information (gender and age) were retrieved at the moment of enrollment. Serum samples were obtained from volunteers and used in molecular detection of CHIKV, MAYV, DENV, ZIKV, and YFV by reverse transcription followed by real-time polymerase chain reaction as well as in genome sequencing aiming phylogenetic analysis. As the main result, we found that from the 98 patients 45 were infected by CHIKV, 32 were infected by serotype 1 of DENV (DENV-1) and six were infected by ZIKV, while 15 were negative for all arboviruses tested. In addition, phylogenetic analysis revealed that all CHIKV-positive samples were of the East/Central/South African (ECSA) genotype, while all DENV-1-positive samples were of the V genotype. These results clearly show that epidemiological surveillance cannot be based only on clinical evaluations. Laboratory diagnosis is important in arbovirus infection that are prevalent in a particular area. These findings also demonstrate the co-circulation of many arboviruses in Western Bahia in 2021.

Impacts of El Niño Southern Oscillation on the dengue transmission dynamics in the Metropolitan Region of Recife, Brazil.

BACKGROUND: This research addresses two questions: (1) how El Niño Southern Oscillation (ENSO) affects climate variability and how it influences dengue transmission in the Metropolitan Region of Recife (MRR), and (2) whether the epidemic in MRR municipalities has any connection and synchronicity. METHODS: Wavelet analysis and cross-correlation were applied to characterize seasonality, multiyear cycles, and relative delays between the series. This study was developed into two distinct periods. Initially, we performed periodic dengue incidence and intercity epidemic synchronism analyses from 2001 to 2017. We then defined the period from 2001 to 2016 to analyze the periodicity of climatic variables and their coherence with dengue incidence. RESULTS: Our results showed systematic cycles of 3-4 years with a recent shortening trend of 2-3 years. Climatic variability, such as positive anomalous temperatures and reduced rainfall due to changes in sea surface temperature (SST), is partially linked to the changing epidemiology of the disease, as this condition provides suitable environments for the Aedes aegypti lifecycle. CONCLUSION: ENSO may have influenced the dengue temporal patterns in the MRR, transiently reducing its main way of multiyear variability (3-4 years) to 2-3 years. Furthermore, when the epidemic coincided with El Niño years, it spread regionally and was highly synchronized.

First description of a multisystemic and lethal SARS-CoV-2 variant of concern P.1 (Gamma) infection in a FeLV-positive cat.

BACKGROUND: Phylogenetic studies indicate bats as original hosts of SARS-CoV-2. However, it remains unclear whether other animals, including pets, are crucial in the spread and maintenance of COVID-19 worldwide. METHODS: In this study, we analyzed the first fatal case of a SARS-CoV-2 and FeLV co-infection in an eight-year-old male cat. We carried out a clinical evaluation and several laboratory analyses. RESULTS: As main results, we observed an animal presenting severe acute respiratory syndrome and lesions in several organs, which led to the animal's death. RT-qPCR analysis showed a SARS-CoV-2 as the causative agent. The virus was detected in several organs, indicating a multisystemic infection. The virus was found in a high load in the trachea, suggesting that the animal may have contribute to the transmission of the virus. The whole-genome sequencing revealed an infection by SARS-CoV-2 Gamma VOC (P.1), and any mutations indicating host adaptation were observed. CONCLUSION: Our data show that FeLV-positive cats are susceptible to SARS-CoV-2 infection and raise questions about the potential of immunocompromised FeLV-positive cats to act as a reservoir for SARS-CoV-2 new variants.

The COVID-19 Humoral Immunological Status Induced by CoronaVac and AstraZeneca Vaccines Significantly Benefits from a Booster Shot with the Pfizer Vaccine.

A third vaccine dose against COVID-19 is already a reality in some countries around the world. In this study, we aimed to evaluate the effectiveness of the Brazilian immunization policy for COVID-19, which involves a booster shot. Participants (n = 210) provided serum samples, which were subjected to enzyme-linked immunosorbent assay (ELISA). Immunological profiles were defined as individuals with or without previous SARS-CoV-2 infection who received at least one vaccine dose in the immunization regimens of AstraZeneca, CoronaVac, or CoronaVac plus a booster shot with Pfizer. In addition, nonvaccinated/infected individuals were also included. As main results, we observed that the numbers of infected individuals were significantly reduced among those who were vaccinated, even with one dose. This result indicates that vaccines are highly protective against COVID-19. However, we observed a significant tendency of serum level decreases of specific antibodies over the time after the second dose. In contrast, the booster shot with the Pfizer vaccine after a CoronaVac immunization regimen showed a significant increase in the specific SARS-CoV-2 IgG serum levels. Moreover, we found that vaccination induced a significantly higher humoral immunological status than only the natural infection with SARS-CoV-2. Collectively, results presented here indicate that vaccines are necessary to induce a robust immunological status, which is maintained, restored, or even improved by booster shots. IMPORTANCE COVID-19 continues to spread around the world despite significant progress in vaccine distribution and population immunity. The dynamics of the antiviral antibody response postvaccination is critical to evaluate vaccine effectiveness across different vaccine platforms and over time. In this study, we evaluate the serum levels of antiviral antibodies in patients from Brazil that received either the CoronaVac or the AstraZeneca vaccine. We found that antibody levels wane over time, vaccines induce protective immunity, and humoral immunity is enhanced with a third vaccine dose. This study reveals that the COVID-19 humoral immunological status induced by vaccines significantly benefits from a booster shot.

Impacts of El Niño Southern Oscillation on the dengue transmission dynamics in the Metropolitan Region of Recife, Brazil

ABSTRACT Background: This research addresses two questions: (1) how El Niño Southern Oscillation (ENSO) affects climate variability and how it influences dengue transmission in the Metropolitan Region of Recife (MRR), and (2) whether the epidemic in MRR municipalities has any connection and synchronicity. Methods: Wavelet analysis and cross-correlation were applied to characterize seasonality, multiyear cycles, and relative delays between the series. This study was developed into two distinct periods. Initially, we performed periodic dengue incidence and intercity epidemic synchronism analyses from 2001 to 2017. We then defined the period from 2001 to 2016 to analyze the periodicity of climatic variables and their coherence with dengue incidence. Results: Our results showed systematic cycles of 3-4 years with a recent shortening trend of 2-3 years. Climatic variability, such as positive anomalous temperatures and reduced rainfall due to changes in sea surface temperature (SST), is partially linked to the changing epidemiology of the disease, as this condition provides suitable environments for the Aedes aegypti lifecycle. Conclusion: ENSO may have influenced the dengue temporal patterns in the MRR, transiently reducing its main way of multiyear variability (3-4 years) to 2-3 years. Furthermore, when the epidemic coincided with El Niño years, it spread regionally and was highly synchronized.