Bioanálise do colostro de nutrizes acometidas pela Covid-19 na gestação e determinantes sociais da saúde da mortalidade materna e de crianças menores de 2 anos relacionada à doença no semiárido brasileiro

Abstract

COVID-19, caused by SARS-CoV-2, has become a global threat to global public health. As the pandemic evolved, infections, hospitalizations and deaths varied between regions in Brazil and across the world, raising questions about risk and protective factors for the disease. This thesis investigated two distinct objectives, which have as a common axis the context of COVID-19 in the context of maternal and child health, and is then structured into two general chapters. Chapter 1 addressed the impact of COVID-19 on maternal and neonatal health with an emphasis on the composition of human milk. In this sense, the first objective of this thesis was to analyze the profile of immunoglobulins, markers of oxidative stress, pro-inflammatory and anti inflammatory cytokines, and lymphoid cells in the colostrum of nursing mothers affected by SARS-CoV-2 during pregnancy, which showed and did not show symptoms of the disease. Using a case-control study design, colostrum samples were collected from 14 nursing mothers with a confirmed diagnosis of COVID-19 during pregnancy (symptomatic group) and from 12 nursing mothers without a diagnosis of the disease (asymptomatic group), between September 2020 and May 2021. The samples were analyzed for IgA and IgG immunoglobulins for the SARS-CoV-2 S protein, markers of oxidative stress, cytokines and chemokines. Immunophenotyping was performed to evaluate the frequency of different cell types in colostrum. Colostrum from the symptomatic COVID-19 pregnancy group contained reduced levels of H2O2, IFN-α2, and GM-CSF. This group also had higher levels of GSH, and a higher proportion of both NK cell subtypes (CD56dim e CD56bright). These findings reinforce the protective role of colostrum even in cases of mild SARS-CoV-2 infection, in addition to demonstrating how adaptive the composition of breast milk is after infections. Chapter 2 of this thesis dealt with the social determinants of health of maternal mortality and lethality of children under 2 years old related to COVID-19 in the Brazilian semi-arid region. It aimed to investigate the association between the number of deaths of pregnant or postpartum women and children under 2 years old due to COVID-19 and the social determinants of health in municipalities that belong to the Brazilian semi-arid region. An ecological study was carried out with national public domain data registered in the Influenza Epidemiological Surveillance Information System (SIVEP-Gripe), from March 2020 to December 2022. Generalized linear models with mixed effects (negative binomial distribution and log link function) were used to analyze the association between maternal and child deaths from COVID-19 and social determinants of health. The analyzes identified a negative and positive association, respectively, between the number of hospital beds (RR=0.77; 95%CI:0.63-0.94) and healthcare costs (RR=1.31; 95%CI:1 .14-1.50) and the number of deaths of children under 2 years old due to COVID-19 in municipalities belonging to the semi-arid region of the country. For maternal mortality, there was no statistically significant association for semi-arid municipalities. These findings reflect the disparities that exist between the municipalities of the states that make up the semi-arid region of Brazil and reinforce that health and social assistance actions must be prioritized to combat infant mortality. Finally, the results found in both chapters reveal the complexity of protective and risk factors for COVID-19, which still represents a public health concern today, particularly for infants under 1 year of age, which reinforces the importance of advancing vaccination coverage for this population, as well as the importance of breastfeeding, especially for children under 6 months of age who do not have vaccines against COVID-19.