Background Qatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess ever and/or current infection prevalence in this population. Methods A cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and current infection positivity through polymerase chain reaction (PCR) testing. Associations with antibody and PCR positivity were identified through regression analyses. Results Study included 2,641 participants, 69.3% of whom were <40 years of age. Anti-SARS-CoV-2 positivity was 55.3% (95% CI: 53.3-57.3%) and was significantly associated with nationality, geographic location, educational attainment, occupation, and previous infection diagnosis. PCR positivity was 11.3% (95% CI: 9.9-12.8%) and was significantly associated with nationality, geographic location, occupation, contact with an infected person, and reporting two or more symptoms. Infection positivity (antibody and/or PCR positive) was 60.6% (95% CI: 58.6-62.5%). The proportion of antibody-positive CMWs that had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI: 7.9-11.0%). Only seven infections were ever severe and one was ever critical—an infection severity rate of 0.5% (95% CI: 0.2-1.0%). Conclusions Six in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or mild infections.

Fluorosis levels and caries prevalence were evaluated in 152 children aged 6-8 yr residing from birth in an area with 5 ppm fluoride in the drinking water. Sixty-two of the subjects had mild fluorosis in both primary and permanent dentition, 31 were defined as moderate, and 4 cases had no signs of fluorosis; 14 cases had a more severe fluorosis level in the primary dentition as compared to 41 cases in which fluorosis was more severe in the permanent dentition. More primary dentitions were free of fluorosis in females than in males (P less than 0.05). No differences between males and females were found in the permanent dentition fluorosis. The decay rate in the permanent dentition gradually increased with increasing fluorosis severity, a finding not observed in the primary dentition. Reasons are discussed for the lower fluorosis level in the primary dentition and the more severe fluorosis in older age groups as well as the fluorosis severity difference by gender.

No abstract

No abstract

No abstract