Self-swabbing versus assisted swabbing for viral detection by qRT-PCR: the experience from SARS-CoV-2 based on a meta-analysis of six prospectively designed evaluations conducted in a UK setting.

PURPOSE: In April 2020, the UK Government implemented NHS Test and Trace to provide SARS-CoV-2 quantitative reverse transcription polymerase chain reaction (qRT-PCR) testing for the public, with nose-and-throat swabbing for samples performed by trained staff. Self-swabbing (SS) would allow rapid scale-up of testing capacity and access. Six studies were undertaken to determine whether SS was as effective for detecting SARS-CoV-2 as swabbing performed by trained staff. METHODS: Six prospective studies were conducted between April-October 2020, using six swab/media combinations. Differences between assisted swabbing (AS) and SS were evaluated for concordance, positivity, sensitivity, cycle threshold (Ct) values and void rates. Statistical analysis was performed using 95% confidence intervals (CIs), paired t-tests and model-based methods. RESULTS: Overall, 3,253 individuals were recruited (median age 37 years, 49% female), with 2,933 having valid paired qRT-PCR results. Pooled concordance rate was 98% (95% CI: 96%, 99%). Positivity rate differences for SS (8.1%) and AS (8.4%) and differences in pooled sensitivities between SS (86%; 95% CI: 78%, 92%) and AS (91%; 95% CI: 78%, 96%) were nonsignificant. Both types of swabbing led to pooled void rates below 2% and strongly correlated Ct values. Age, sex and previous swabbing experience did not have a significant impact on concordance or sensitivity. CONCLUSION: The UK adopted a policy to promote self-testing for SARS-CoV-2 based on data demonstrating equivalence of SS versus AS. Positive outcomes with SS are likely generalisable to testing for other respiratory pathogens, and we consider self-sampling and self-testing essential for future pandemic preparedness.

Does BCG revaccination protect against the development of asthma?

Single BCG vaccination has been considered as a protective factor against asthma. However the effect of a second dose of BCG on the prevalence rate of asthma and asthma-allergic rhinitis-eczema comorbidity has not been studied exclusively among adolescents. In this ISAAC protocol-based cross sectional study we assessed the association between one single versus two doses of BCG among 2213 individuals aged 13-14 years old. We found no association between BCG revaccination and asthma, associated (OR = 0.68, 95% CI, 0.37-1.25) or not to allergic rhinitis and/or atopic eczema (OR = 1.07, 95% CI, 0.84-1.36).

Seroprevalence and potential risk factors for Helicobacter pylori infection in Brazilian children.

BACKGROUND: Helicobacter pylori infection has been proved to be of great relevance to public health in unindustrialized countries, especially in low socioeconomic groups. Poor hygiene, deficient sanitation, and crowded conditions have been reported as risk factors for this infection. In this work, we investigated whether social and demographic characteristics were associated with anti-H. pylori IgG antibodies in 1104 children aged 4-11 years old from Salvador, a large city located in northeastern Brazil. METHODS: Standardized questionnaires were used to obtain social, demographic, and environmental data for the studied population in two periods of time (from 1997 to 2003 and in 2005). Anti-H. pylori IgG antibodies were assessed by indirect enzyme-linked immunosorbent assay in 2005. RESULTS: Anti-H. pylori IgG antibody was present in 28.7% of the children. Among the studied variables, the following were positively associated with the presence of anti-H. pylori antibodies in multivariable analyses: age above 8 years old (OR = 1.72, 95% CI = 1.23-2.40), a larger sibling number (OR = 1.66, 95% CI = 1.26-2.18), nursery attendance (OR = 1.49, 95% CI = 1.04-2.12), location of the house at an unpaved street (OR = 2.03, 95% CI = 1.44-2.87) and absence of a flush toilet (OR = 1.32, 95% CI = 1.00-1.74). CONCLUSION: Our data show that H. pylori infection in children from a major Brazilian city is associated with variables indicative of a crowded environment and deficient sanitation/habitation conditions, leading to the conclusion that improvements in hygiene and social conditions may protect children against this infection.

Ecological study of socio-economic indicators and prevalence of asthma in schoolchildren in urban Brazil.

BACKGROUND: There is evidence of higher prevalence of asthma in populations of lower socio-economic status in affluent societies, and the prevalence of asthma is also very high in some Latin American countries, where societies are characterized by a marked inequality in wealth. This study aimed to examine the relationship between estimates of asthma prevalence based on surveys conducted in children in Brazilian cities and health and socioeconomic indicators measured at the population level in the same cities. METHODS: We searched the literature in the medical databases and in the annals of scientific meeting, retrieving population-based surveys of asthma that were conducted in Brazil using the methodology defined by the International Study of Asthma and Allergies in Childhood. We performed separate analyses for the age groups 6-7 years and 13-14 years. We examined the association between asthma prevalence rates and eleven health and socio-economic indicators by visual inspection and using linear regression models weighed by the inverse of the variance of each survey. RESULTS: Six health and socioeconomic variables showed a clear pattern of association with asthma. The prevalence of asthma increased with poorer sanitation and with higher infant mortality at birth and at survey year, GINI index and external mortality. In contrast, asthma prevalence decreased with higher illiteracy rates. CONCLUSION: The prevalence of asthma in urban areas of Brazil, a middle income country, appears to be higher in cities with more marked poverty or inequality.

Influenza vaccination in Brazil: rationale and caveats.

Mass vaccination campaigns against influenza in the elderly have been conducted in Brazil since 1999. A search of the literature on influenza in Brazil indicated that data on disease burden are still scarce and inaccurate. Published data seem to indicate that vaccination has produced some impact in the southern and southeastern regions but not in other regions of Brazil. A discussion of the technical and scientific rationale for mass immunization against influenza is presented and it is argued that the current strategy has not taken into account potential differences in disease occurrence in different areas. It is suggested some epidemiological surveillance actions needed to address major concerns regarding mass influenza vaccination and its impact in Brazil.

Outbreak of aseptic meningitis and mumps after mass vaccination with MMR vaccine using the Leningrad-Zagreb mumps strain.

Data from routine surveillance during two mass immunisation campaigns (MIC) with Measles-mumps-rubella (MMR)vaccine using Leningrad-Zagreb mumps strain in two states in Brazil were analysed to estimate the risk of vaccine-related meningitis and mumps. Increase in the incidence of the two diseases was observed in both states, 3 weeks after the vaccination campaigns. The estimated number of doses applied per one case of vaccine-related meningitis ranged from 6199 (95% CI: 4854-8058) to 19,247 (95% CI: 12,648-29,513) depending on the diagnostic criteria used and state. It was 300 doses (95% CI: 286-317) for each case of mumps. The implications for vaccination policy are discussed.