[ad_1]
Outbreaks of coronavirus disease 2019 (COVID-19) are common in healthcare facilities such as hospitals and nursing homes, as physical distancing is difficult to achieve despite all the infection prevention and control measures put in place. implemented in these establishments. Early detection of cases helps isolate individuals and better prevent secondary transmissions, although pre- or asymptomatic cases that may still be transmitted between healthcare workers and patients should also be considered.
In an article recently published in the journal Infection control and hospital epidemiology, researchers are studying the dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in a geriatric hospital ward by whole genome sequencing. Here, the researchers find that considerable secondary transmission occurs between patients and healthcare workers.
Study: Unexpected details of nosocomial transmission revealed by whole genome sequencing of severe acute respiratory syndrome coronavirus 2. Image Credit: tele52 / Shutterstock.com
Proof of nosocomial transmission
People who tested positive for SARS-CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) of nasopharyngeal samples taken from a 30-bed hospital ward in Sweden over a period of one month were included. in the study. In total, this included 32 patients and 15 healthcare workers.
The median age of the patients was 84 years, of which about half were men. Importantly, 44% of the patients died during the study, all with significantly higher viral loads than those who survived. The authors note that many of these people had suffered hip fractures, which has therefore been reported as a major comorbidity for COVID-19.
Whole genome sequencing was then performed on the samples, which revealed that the cases in the ward were represented by three distinct clades of 20A, B and C, the cases known to have been acquired during the hospital stay. being more genetically similar.
The ward that housed the patients was separated into 8 rooms, and the group followed each epidemic case by proximity. All patients infected with SARS-CoV-2 clade-20A1 shared chambers A or C, while clade-20A2 and 20C were restricted to chambers E and H, respectively. Clade-20B was the most prevalent, present everywhere except room C, and was also most commonly found among healthcare workers, followed by clade 20A1 and A2.
The authors suggest that this represents four separate introductions of the virus into the service, clades 20A1, A2, B and C, the first three of which subsequently underwent secondary transmission to at least one other individual.
Monitoring SARS-CoV-2 introductions
The first and only case of clade 20C was detected in a patient four days after admission, well during the presymptomatic period of COVID-19, and was therefore likely obtained as a result of community transmission. This patient was discharged the next day and does not appear to have transmitted the virus to another patient or healthcare professional during this time.
Clade 20A1 may have been introduced into the ward by one patient, as other patients sharing room A were soon diagnosed with the same strain. About a week later, residents in Room C were infected, suggesting intermediate transmission from a health worker.
The 20A2 clade was first detected in a healthcare worker and later in a single patient, also suggesting secondary transmission to a patient. The most common clade, B, was detected in two patients who were physically separated at the start of the study. Thus, these patients also likely acquired the infection from a healthcare professional before widespread secondary transmission to other patients occurred.
Overall, the researchers in the current study indicate that there is strong support for nosocomial infections, both from healthcare workers and other patients, occurring in 78% of patients. Of these, six are considered patient-to-patient; however, the majority may still come from healthcare workers.
The authors point out that it is often difficult to determine the direction of transmission given the high number of asymptomatic cases likely to occur, especially since detailed clinical information was not available for healthcare workers in the area. this study.
Although healthcare workers involved in this study used appropriate protective equipment and engaged in infection prevention and control measures, the rate of adherence is not known. It is therefore difficult to assess their effectiveness in preventing secondary transmission.
Regular testing that can identify infectious COVID-19 before symptoms manifest is probably the most effective method of preventing nosocomial infections, as it allows individuals to be quarantined before outbreaks occur.
Source link
