The asymptomatic carriage of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease 2019 (COVID-19), is a potentially significant source of transmission. Yet, it remains relatively poorly understood.
Many past studies have shown that asymptomatic or pre-symptomatic carriers pose threats to those they mingle with within a certain period. Community surveillance determines who are carriers, can assess the prevalence of the pathogen with greater accuracy and ultimately helps to contain its spread.
A new study by UK-based researchers at the University of Glasgow, Department of Public Health, NHS Ayrshire and Arran, Public Health Scotland, and the Strathclyde University conducted a mass, asymptomatic screening of patients in dental surgeries across Scotland to assess illustrate its potential utility in curbing silent transmission. In doing so, they showed that of the total dental patients a clinic has tested, 22 asymptomatic patients tested positive. The study’s findings bolster the notion that this form of asymptomatic mass screening can help detect and prevent transmission chains and curb the spread of SARS-CoV-2 to vulnerable individuals.
Dental services amid the pandemic
Due to the risk of transmission tied to receiving dental care, during the lockdown period in Scotland, all dental practices were not able to see patients. Disruption of dental services continues with significantly reduced capacity during the pandemic.
Even if many clinics have already reopened in the ‘new normal’, ongoing precautions include COVID-19 symptom screening and the use of enhanced personal protective equipment (PPE).
To contribute to the COVID-19 testing and surveillance of Scotland, dental teams screened patients to ensure they had no COVID-19 symptoms and they could readily be trained to conduct COVID-19 swab testing.
COVID-19 infection in dental patients
The study, published on the pre-print medRxiv* server, highlights the prevalence of asymptomatic COVID-19 and its associated transmission risks. Across Scotland, 31 dental care centers invited asymptomatic screened patients who are more than 5 years old to participate.
After getting the patient’s verbal consent, symptom history, and sociodemographic profile, the dental practitioners obtained a combined oropharyngeal and nasal swab sample using standardized VTM-containing test kits. The Lighthouse Lab processed the samples and patients were informed of their results via SMS or e-mail.
Over the course of around 13 weeks, of the total 4,032 patients tested, 22 patients tested positive for SARS-CoV-2, with an overall positivity rate of 0.6 percent. All the positive patients were followed up by the national contact tracing program. None of the positive tests, however, had the S-gene drop-out suggestive of the new UK variant also known as the SARS-CoV-2 VUI 202012/01.
“The positivity rate in this patient group reflects the underlying prevalence in the community at the time,” the team explained. The researchers noted the importance of using PPE and infection control measures when community infection levels are rising. This is useful to reduce healthcare team fatigue as the pandemic continues to spread.
The surveillance had many advantages. First, trained dental healthcare teams collected high-quality and complete data. They were also able to get samples for testing. Also, there was no need for the clinical teams to use additional PPEs as they were already wearing them to provide dental care.
These data are a salient reminder, particularly when community infection levels are rising, of the importance of appropriate ongoing Infection Prevention Control and PPE vigilance, which is relevant as healthcare team fatigue increases as the pandemic continues,” the researchers concluded in the study.
They added that dental settings are a valuable location for public health surveillance. An accurate picture of asymptomatic cases in the UK may prove particularly crucial in the coming months as the nation grapples with a new variant of SARS-CoV-2 thought by experts to be up to 70% more transmissible than earlier ones.
COVID-19 pandemic case toll
Providing new avenues for testing and surveillance can help reduce the burden of the healthcare system, which has been impacted as new surges of cases continue.
To date, there are more than 85.73 million COVID-19 cases and over 1.85 million deaths. The United States and India report the highest number of cases, with at least 20.82 million and 10.35 million cases, respectively.
The U.S. and Brazil report the highest number of deaths related to COVID-19, with over 353,000 and 196,000 deaths.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
- Conway, D., Edwards, C., Watling, C., Robertson, C., Braid, R. et al. (2020). SARS-CoV-2 positivity in asymptomatic-screened dental patients. medRxiv. doi: https://doi.org/10.1101/2020.12.30.20248603, https://www.medrxiv.org/content/10.1101/2020.12.30.20248603v