PREPRINT (not yet peer reviewed):
SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homesNeil SN Graham, Cornelia Junghans, Rawlda Downes, Catherine Sendall, Helen Lai, Annie McKirdy, Paul Elliott, Robert Howard, David Wingfield, Miles Priestman, Marta Ciechonska, Loren Cameron, Marko Storch, Michael Crone, Paul Freemont, Paul Randell, Robert McLaren, Nicola Lang, Shamez Ladhani, Frances Sanderson, David J SharpmedRxiv 2020.05.19.20105460; doi: https://doi.org/10.1101/2020.05.19.20105460
Aim: to understand SARS-Co-V-2 infection and transmission in care homes to develop preventative strategies.
An outbreak investigation carried out in 4 nursing homes affected by COVID-19 outbreaks in central London. The study collected data on 340 participants and 70 staff members. The study was motivated by the observation that many residents who became acutely unwell and died had not displayed the “typical” SARS-CoV-2 symptoms of fever and cough. The study was carried out 21 days after the first positive test in those homes, and 27 days after the first COVID-attributed death.
- Two prevalence surveys one one week apart and documentation of symptoms. All residents underwent testing and three of the four homes were also offered testing.
- The five key symptoms recorded: new fever, cough and/or breathlessness (the “typical” symptoms), newly altered mental status or behaviour, anorexia, diarrhoea or vomiting (“atypical” symptoms).
- The outcomes measured were mortality (all and attributed to COVID-19), prevalence of infection and symptoms, in residents and staff.
- Medical certificates of cause of deaths were reviewed.
- Between the 1st of March to the 1st of May, 26% (103 out of 394) of all residents died, with a peak of deaths in the first week of April. This was 203% higher than the number of deaths observed in the same time period in the previous two years.
- 40% of residents had positive tests and, of these, 43% were asymptomatic, 18% had atypical symptoms. 4% of asymptomatic staff tested positive for SARS-CoV-2. The symptom with the strongest association with a positive test result on its own was new onset anorexia. Fever, altered mental state/behaviour or diorrhea were not independently associated with a positive test.
- Of the 49 residents who were asymptomatic at the first test, only 5 (10%) developed symptoms later. It is possible that a proportion of “asymptomatic” residents may have been “post-symptomatic”.
- Residents had an average of 3 co-morbidities, of these dementia was the most common (57%), followed by cardiovascular disease (51%). Cardiovascular disease was the only co-morbidity significantly associated with increased mortality.
- Staff absence rates between 1st March and 1st May were more than three times the previous levels. 70 asymptomatic staff were tested, of these 3 (4%) tested positive.
- Genetic sequencing of SARS-CoV-2 showed that, although there were some similar sequence variants within a single home, there were also multiple distinct clusters within single nursing homes.
Implications identified by the authors:
- The results support the need for a policy of universal and systematic testing, coupled by high level of surveillance. Regular testing would enable positive residents to be rapidly identified and the timely implementation of appropriate measures.
- The initial national drive of using fever or cough symptoms as the criteria for testing and isolating individuals may have contributed to delays in implementing appropriate infection control measures and to the large number of deaths observed.
Limitations reported by the authors:
- Mortality had to be inferred as the cause of excess deaths due to lack of tests availability before the study started in day 21.
- The recording of symptoms is likely to be incomplete due to difficulties eliciting them and potentially incomplete recording.