Objectives: To assess the accuracy of three immunochromatographic rapid tests for salivary detection of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) antigens and the reliability of these tests comparing saliva with plasma samples.Materials and Methods: Plasma and saliva samples from 62 patients diagnosed with coronavirus disease 2019 (COVID‐19) and 20 healthy volunteers were assayed. IgM/IgG antibody against SARS‐COV‐2 was detected using three immunochromatographic rapid tests and compared with real‐time reverse transcription‐polymerase chain reaction (qRT‐PCR).Results: The tests’ overall accuracy for detecting anti‐SARS‐CoV‐2 antibodies ranged from 75.6 to 79.3 for saliva and 86.6–87.8 for plasma tests. The sensitivity of saliva and plasma tests increased with the severity of COVID‐19 signs and symptoms. The chance of a positive plasma test in participants with a positive qRT‐PCR test was 2.27 greater than a positive saliva test.Conclusions: Although rapid immunochromatographic tests are more accurate using plasma than saliva, which was expected considering its original use, our findings support the use of saliva as a straightforward supplementary method to assess seroconversion in patients with COVID‐19, with important sensitivity and sensibility, especially in severe and critical cases.

Immune responses after COVID-19 vaccination should be evaluated in different populations around the world. This study compared antibody responses induced by ChAdOx1 nCoV-19, CoronaVac, and BNT162b2 vaccines. Blood samples from vaccinees were collected pre- and post-vaccinations with the second and third doses. The study enrolled 78 vaccinees, of whom 62.8% were women, with the following median ages: 26 years—ChAdOx1 nCoV-19; 40 years—CoronaVac; 30 years—BNT162b2. Serum samples were quantified for anti-RBD IgG and anti-RBD IgA and anti-spike IgG by ELISA. After two vaccine doses, BNT162b2 vaccinees produced higher levels of anti-RBD IgA and IgG, and anti-spike IgG compared to ChAdOx1 nCoV-19 and CoronaVac vaccinees. The third dose booster with BNT162b2 induced higher levels of anti-RBD IgA and IgG, and anti-spike IgG in CoronaVac vaccinees. Individuals who reported a SARS-CoV-2 infection before or during the study had higher anti-RBD IgA and IgG production. In conclusion, two doses of the studied vaccines induced detectable levels of anti-RBD IgA and IgG and anti-spike IgG in vaccinees. The heterologous booster with BNT162b2 increased anti-RBD IgA and IgG and anti-spike IgG levels in CoronaVac vaccinees and anti-RBD IgA levels in ChAdOx1 nCoV-19 vaccinees. Furthermore, SARS-CoV-2 infection induced higher anti-RBD IgA and IgG levels in CoronaVac vaccinees.

Acute Diarrheal Disease (ADD) remains a major global health concern, with rotavirus A (RVA) and human adenovirus (HAdV) as key viral agents. This study evaluated the positivity rate and molecular characterization of RVA and HAdV in fecal samples from 114 children (0–5 years) in Goiás, Brazil, between January 2022 and December 2023, following the COVID-19 public health emergency. RVA was detected in 13.1% of samples (genotypes G1 and G6 associated with P[8]) and HAdV in 15.8% (genotypes A31, B3, C1, and C6), with two coinfection cases also being detected (1.7%). RVA predominated in unvaccinated 0-to-6-month-old children, while most asymptomatic cases occurred among vaccinated children. HAdV was also mainly identified in this age group, including asymptomatic children. Viral positivity was more common among children without access to treated water. In conclusion, this study underscores the ongoing circulation and genetic diversity of RVA and HAdV among children in Goiás in the post-pandemic period. The findings highlight the influence of vaccination coverage and sanitation on viral positivity, emphasizing the need for integrated public health strategies. Continuous molecular surveillance remains essential to detect emerging genotypes and guide effective prevention and control measures against ADD.