An unusual seroconversion profile in a pregnant woman infected with the human immunodeficiency virus-1: Need for using later generations HIV screening assays

The first HIV-1 marker that appears in blood following infection is HIV-1 RNA and usually the load is in millions of copies/ ml preceding seroconversion. A 24-year-old pregnant woman, gravida 2, parity 1 was tested for HIV as part of antenatal screening. Three samples were collected and tested from this individual over a period 70 days. The HIV-1 RNA level during seroconversion phase was very low contrary to the well understood natural history of HIV infection. The reactivity rate in the ELISA and the Western Blot profile showed a gradual increase over the 70 days with a weak reactivity in a second generation assay (detects IgG only) for the third sample. This case illustrates the uncertainties regarding the serological window period in HIV infection and the need to use at least a third generation assay in testing centres for early detection of HIV infection

Short-term exposure to ambient air pollution and individual emergency department visits for COVID-19:a case-crossover study in Canada

Abstract Background: Ambient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial. Objective: To evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits. Methods: We conducted a case-crossover study of 78 255 COVID-19 ED visits in Alberta and Ontario, Canada between 1 March 2020 and 31 March 2021. Daily air pollution data (ie, fine particulate matter with diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO₂) and ozone were assigned to individual case of COVID-19 in 10 km × 10 km grid resolution. Conditional logistic regression was used to estimate associations between air pollution and ED visits for COVID-19. Results: Cumulative ambient exposure over 0–3 days to PM2.5 (OR 1.010; 95% CI 1.004 to 1.015, per 6.2 µg/m³) and NO₂ (OR 1.021; 95% CI 1.015 to 1.028, per 7.7 ppb) concentrations were associated with ED visits for COVID-19. We found that the association between PM2.5 and COVID-19 ED visits was stronger among those hospitalised following an ED visit, as a measure of disease severity, (OR 1.023; 95% CI 1.015 to 1.031) compared with those not hospitalised (OR 0.992; 95% CI 0.980 to 1.004) (p value for effect modification=0.04). Conclusions: We found associations between short-term exposure to ambient air pollutants and COVID-19 ED visits. Exposure to air pollution may also lead to more severe COVID-19 disease