Introduction
Since the first report of an outbreak of pneumonia cases caused by a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019 in Wuhan, China, the disease has rapidly spread around the world and was defined as a pandemic by the World Health Organization on the 11th of March 2020. As of 29thof June, more than ten million infections and over 500,000 deaths related to coronavirus disease (COVID-19) have been confirmed worldwide1.
Different countries have adopted varying degrees of physical distancing and mitigation strategies with diverse impacts on their transmission rates, death toll and economies2, 3. It has been proposed that universal testing with the isolation of cases and contact tracing could reduce the prevalence of the disease and end the pandemic4. In Australia, restriction measures were first implemented on the 23rd of March (with the closure of bars, clubs, cinemas, places of worship, casinos and gyms), and two days later the country closed its borders. As part of the mitigation strategy, the Victorian state government implemented a screening “blitz” in the last week of April. The purpose of this was to screen a large number of people and therefore allow for contact tracing and physical isolation of positive asymptomatic individuals prior to easing of restrictions. After a peak in the number of cases in the end of March both in Australia and the state of Victoria, a steep decline in the daily number of new cases became evident, and restrictions have gradually and progressively been eased since the second half of May. Nevertheless, estimates of the infection rates among asymptomatic individuals in Australia are currently unavailable, and whether universal screening is necessary in low disease prevalence settings is unclear.
Preliminary data suggests that pregnant women are not at increased risk of severe disease and its complications compared to the general population, nor is there convincing evidence of vertical transmission5, 6. However, within the pandemic context, pregnancy represents a unique situation as women have multiple interactions with the health care system and most are ultimately admitted to hospital for childbirth. Therefore, it is possible that pregnant women may be a source of infection to others who they encounter during their frequent attendance to healthcare facilities, so it is vital to understand the rates of asymptomatic infection in this population.
This study aims to assess the prevalence of SARS-CoV-2 positive tests among pregnant women attending routine antenatal care within a defined study period during the coronavirus disease pandemic in Victoria, Australia.