Abstract Background: Coronavirus disease 2019 (COVID‑19) vaccines are effective at helping protect against severe disease and death from variants; however, incident of breakthrough infection in vaccinated patients has been increased. Therefore, we aimed to assess the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) new variants of concern in the communities and investigate vaccine breakthrough cases on our laboratory (Ayass Bioscience LLC) confirmed detection of COVID-19 variants in Dallas-Fort Worth (DFW), Texas. Methods: Epidemiologic study has been performed at our laboratory. We studied the viral whole-genome sequence and genotyping analysis on 166 symptomatic cases of COVID-19 which were randomly selected from nasal swab positive cases assessed from June 1st to August 30th, 2021, by reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (CT) values. COVID-19 variants were identified to be dominated by B.1.617.2 (89.2%) and followed by AY.3 (1.8%), B.1.1.7 (4.8%), a combination of B.1.526.1 and B.1.617.2 (3%), B.1.621 (0.6%), and P.2 (0.6%). Result: The CT values showed significant difference among the three age groups: <30 years, 31-60 years, and >60 years by one-way ANOVA (N1: F (2, 118) =4.96, p=0.009; N2: F (2, 118) =4.95, p=0.009). No significant difference was observed by symptom, status of immunization, or vaccine manufacturer. A two-way ANOVA was performed to examine the effect of gender and variant group (Delta and other variants) on the CT values. The analyses revealed a statistically significant interaction between the effect of gender and variant group (N1, F (1.117) = 3.906, p = 0.05; N2, F (1, 117) = 7.402, p = 0.008). Conclusion: Our study shows that Delta, the dominant variant of COVID-19, is spreading in the communities, and vaccine breakthrough cases occurred in the majority of Delta variant (91%) followed by AY.3 (5%), B.1.1.7 (2%) and 2% of the double variant of B.1.526.1 and B.1.617.2. The incidence of the breakthrough cases was not linked to a specific manufacturer. The CT value is likely to associate with age. This study also supports our laboratory’s ongoing efforts to sequence the SARS-CoV-2 virus from positive patient samples to identify the new viral variants and possible vaccine breakthrough mutations in the community.