70% of residents and 56% of workers infected with SARS-CoV-2 in nursing homes are asymptomatic, according to a study by the Hospital Vall d’Hebrón in Barcelona carried out in 69 residences, with a sample of almost 6,000 persons.
The study, published in the journal Emerging Infectious Diseases, is the largest in the world to date on the impact of COVID-19 in residences and has shown that 24% of residents and 15% of workers analyzed they were infected.
In a press conference, the head of Epidemiology at the Vall d’Hebron Hospital, Magda Campins, presented the work on Thursday together with the head of Infectious Diseases, Benito Almirante; the director of the Mountain Primary Care Service of Barcelona, Elisabeth Martín; the coordinator of the team of nurses involved in the study, Maria Gutiérrez-San Miguel; and the head of the Microbiology service, Tomàs Pumarola.
The study was carried out between April 10 and 24 in public and private residences in the hospital’s area of influence and initially had the objective of controlling transmissions in these centers and giving tools and training to its staff.
Specifically, the researchers analyzed the presence of symptoms related to COVID-19 and the results in the PCR tests of 3,214 residents and 2,655 nursing home workers, of which 23.9% of users and 15.2% staff were positive.
“These data demonstrate a very high transmission of the virus in these centers, especially favored by the characteristics of the residences, such as shared rooms and bathrooms, other common spaces, and the coexistence of dependent people who require a lot of attention,” Martín said.
Campins highlighted that the high number of asymptomatic infected has been a “surprising” result and has pointed out that it has influenced the design of the new protocol for action in residences in Catalonia recently presented.
“If we want to cut the transmission, we must act very quickly and taking into account all the people, not just the symptomatic ones because, as this study has shown, there can be many asymptomatic forms,” he detailed.
Regarding the high number of asymptomatic residents, Campins has admitted that there may be a bias because some symptoms of COVID-19 such as loss of smell, difficulty breathing, tiredness or headache are nonspecific and difficult to record. in a population as fragile as this.
The study had a team of between 8 and 12 nurses from Vall d’Hebrón and a similar one from primary care that went to the residences to do around 500 daily PCR tests, which in less than 24 hours were analyzed by the hospital’s Microbiology laboratory.