Defining the peak: Point prevalence of SARS-CoV-2 using randomised sampling.

Since Queensland eased border restrictions to the rest of Australia on 13 December 2021, notified cases of Coronavirus disease 2019 (COVID-19) dramatically increased, with the SARS-CoV-2 Omicron variant now the most widespread variant of concern: 145,881 cases and 13 deaths were recorded in Queensland in the month following the opening of the border. For an effective public health response to a highly transmissible disease, it is important to know the prevalence in the community, but the exponential increase in cases meant that many with symptoms had difficulty getting tested. We implemented a surveillance program on the Gold Coast that used a modified randomised household cluster survey method to estimate the point prevalence of individuals with SARS-CoV-2 detected by polymerase chain reaction (PCR). The estimated point prevalence of SARS-CoV-2 detected by PCR on self-collected swabs was 17.2% on the first visit to households (22 January 2022). This subsequently decreased to 5.2% (5 February 2022) and finally to 1.1% (19 February 2022). Out of 1,379 specimens tested over five weeks, 63 had detected SARS-CoV-2 and 35 (55.6%) were sequenced. All were SARS-CoV-2 variant: B.1.1.529 (i.e. Omicron). This surveillance program could be scaled up or reproduced in other jurisdictions to estimate the prevalence of COVID-19 in the community.Since Queensland eased border restrictions to the rest of Australia on 13 December 2021, notified cases of Coronavirus disease 2019 (COVID-19) dramatically increased, with the SARS-CoV-2 Omicron variant now the most widespread variant of concern: 145,881 cases and 13 deaths were recorded in Queensland in the month following the opening of the border. For an effective public health response to a highly transmissible disease, it is important to know the prevalence in the community, but the exponential increase in cases meant that many with symptoms had difficulty getting tested. We implemented a surveillance program on the Gold Coast that used a modified randomised household cluster survey method to estimate the point prevalence of individuals with SARS-CoV-2 detected by polymerase chain reaction (PCR). The estimated point prevalence of SARS-CoV-2 detected by PCR on self-collected swabs was 17.2% on the first visit to households (22 January 2022). This subsequently decreased to 5.2% (5 February 2022) and finally to 1.1% (19 February 2022). Out of 1,379 specimens tested over five weeks, 63 had detected SARS-CoV-2 and 35 (55.6%) were sequenced. All were SARS-CoV-2 variant: B.1.1.529 (i.e. Omicron). This surveillance program could be scaled up or reproduced in other jurisdictions to estimate the prevalence of COVID-19 in the community.

Mechanically resolving noncovalent bonds using acoustic radiation force.

The resolution of molecular bonds and subsequent selective control of their binding are of great significance in chemistry and biology. We have developed a method based on the use of acoustic radiation force to precisely dissociate noncovalent molecular bonds. The acoustic radiation force is produced by extremely low-power ultrasound waves and is mediated by magnetic particles. We successfully distinguished the binding of antibodies of different subclasses and the binding of DNA duplexes with a single-base-pair difference. In contrast to most ultrasound applications in chemistry, the sonication probe is noninvasive and requires a sample volume of only a few microliters. Our method is thus viable for noninvasive and accurate control of molecular bonds that are widely encountered in biochemistry.

Well-defined and sequence-specific noncovalent binding forces of DNA.

The specific binding between the two DNA strands in a double helix is one of the most fundamental and influential molecular interactions in biochemistry. Using force-induced remnant magnetization spectroscopy (FIRMS), we obtained well-defined binding forces of DNA oligomers, with a narrow force distribution of 1.8 pN. The narrow force distribution allows for directly resolving two DNA duplexes with a single base-pair difference in the same sample. Therefore, binding force can serve as a discriminating parameter for probing different DNA interactions. Furthermore, we observed that the binding forces depend on the position of the mismatching base pair. Our results show that FIRMS is capable of high-precision mechanical measurements of biochemical processes involving multiple DNA interactions and has the potential for characterizing the binding strength of materials based on DNA origami.