Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) to detect SARS-CoV-2 RNA is an essential test to monitor the occurrence of COVID-19. A methodology is proposed for the determination of maximum pool size and adjustments of cut-off values of cycle threshold ($C_t$ in RT-qPCR pool testing, to compensate for the dilution caused by pooling. The trade-off between pool size and test sensitivity is stated explicitly. The procedure was designed to ensure that samples that would be detectable in individual testing remain detectable in pool testing. The proposed relaxation in cut-off is dependent on the pool size, allowing a relatively tight correction to avoid loss of detection of positive samples. The methodology was evaluated in a study of pool testing of adults attending a public emergency care unit, reference for COVID-19 in Belo Horizonte, Brazil, and presenting flu-like symptoms. Even samples on the edge of detectability in individual testing were detected correctly. The proposed procedure enhances the consistency of RT-qPCR pool testing by enforcing that the scales of detectability in pool processing and in individual sample processing are compatible. This may enhance the contribution of pool testing to large-scale testing for COVID-19.

The pool testing technique optimizes the number of tests performed and reduces the delivery time of results, which is an interesting strategy for the health crisis caused by the COVID-19 pandemic. This integrative review investigated studies in which pool testing was carried out for epidemiological or screening purposes to analyze its clinical or cost effectiveness and assessed the applicability of this method in high-, middle-, and low-income countries. This integrative review used primary studies published in the MEDLINE, EMBASE, Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), and Cochrane Library databases. A total of 435 studies were identified: 35.3% were carried out in Asia, 29.4% in Europe, 29.4% in North America, and 5.9% in Oceania. This review suggests that pool testing in the general population may be a useful surveillance strategy to detect new variants of SARS-CoV-2 and to evaluate the period of immunogenicity and global immunity from vaccines.

Highlights Pool testing is simultaneously performed on multiple samples to efficiently and cost-effectively detect COVID-19. Pool testing can optimize resource utilization and expand diagnostic access, and is a viable alternative for developing countries with limited access to testing. To optimize resources, the pool size was determined by estimating COVID-19 prevalence in the study population. ABSTRACT This study proposes a strategy for large-scale testing among a large number of people for the early diagnosis of COVID-19 to elucidate the epidemiological situation.

In this study, we tested the hypothesis that the immunosenescence profile could account for the disproportional susceptibility of the elderly to severe forms of COVID‐19. The immunological profiles of volunteers residing in endemic and non‐endemic areas for chronic infectious diseases were analyzed at the early stage of SARS‐CoV‐2 infection. A unique signature of inflammatory plasma mediators was identified in COVID‐19 volunteers when compared to individuals with other flu‐like syndromes. COVID‐19 severity correlated with high levels of inflammatory mediators; among them, CXCL9, a serum marker of aging. Patients who progressed to hospitalization displayed high frequencies of CD8 ⁺ and CD4 ⁺ T cells expressing exhaustion and senescence markers and showed reduced and more mature B cell repertoires, which are typical of senescence. They also had an acceleration of epigenetic age measured by DNA methylation. Therefore, severe COVID‐19 correlated with phenotypic, functional, and epigenetic features of accelerated immunosenescence at the onset of infection.

Highlights ■ Probability of infection with a high SARS-CoV-2 viral load depends on mask-wearing habits. ■ The higher probability of infection with high viral load occurs for individuals that don’t use mask regularly [47.3%–79.8%]. ■ For individuals who use masks regularly, the probability is 38.6%–52.1%. ABSTRACT Objective: Previous studies indicated that face masks reduce the probability of infection by SARSCoV- 2 but did not examine the relationship between SARS-CoV-2 viral load and mask usage. This study analyzed this relationship. Methods:

Resumo Objetivo Demonstrar a viabilidade da utilização combinada da autocoleta de swab nasofaríngeo e pool testing para detecção do SARS-CoV-2 em inquéritos epidemiológicos. Métodos A experiência envolveu amostra de 154 estudantes da Universidade Federal de Minas Gerais, que realizaram a autocoleta do swab nasofaríngeo em cabines individuais e sem supervisão. O teste molecular foi realizado utilizando-se a técnica de pool testing. Resultados A obtenção de amostras durou cerca de 5 minutos por pessoa. Realizou-se análise para detecção de RNA endógeno em 40 amostras e os resultados indicaram que não houve falhas decorrentes da autocoleta. Nenhum dos pools detectou presença de RNA viral. O custo da realização do teste molecular (RT-PCR) por pool testing com amostras obtidas por autocoleta foi cerca de dez vezes menor do que nos métodos habituais. Conclusão As estratégias investigadas mostraram-se economicamente viáveis e válidas para a pesquisa de SARS-CoV-2 em inquéritos epidemiológicos.