What proportion of care home outbreaks are caused by norovirus? An analysis of viral causes of gastroenteritis outbreaks in care homes, North East England, 2016-2018

Abstract

Background Outbreaks of infectious gastroenteritis are common in care homes for the elderly. Norovirus can cause these outbreaks, but diagnosis is frequently based solely on clinical characteristics. Our objective in this study was to describe the epidemiology of norovirus and other gastrointestinal pathogens in these settings. Methods We analysed surveillance data from gastroenteritis outbreaks reported in North East England between 04 July 2016 to 01 July 2018. Stool samples taken during these outbreaks were tested for a range of viral and bacterial pathogens. We described the epidemiology of these outbreaks and explored the characteristics of norovirus outbreaks versus from other viral causes using multivariable logistic regression. Results From the 566 care home gastroenteritis outbreaks in this study, we found that norovirus was the pathogen most frequently isolated. Norovirus was detected in 64% of outbreaks with submitted stool samples. Sapovirus was found in 13%; rotavirus in 11%. We found that norovirus outbreaks were associated with higher attack rates (aOR 5.92, 95% CI 2.30-16.50) and larger care homes (aOR 2.35, 95% CI 1.05-5.38), compared to outbreaks caused by other viral pathogens. Conclusions These results are important as they quantify the contribution of norovirus to gastroenteritis outbreaks in care homes. Given this evidence, we emphasize the importance of non-specific outbreak interventions that can affect the impact of all such outbreaks. We further recommend that these findings are used to inform the implementation strategies of any norovirus-specific interventions such as a norovirus vaccine.

The 2020 SARS-CoV-2 epidemic in England: key epidemiological drivers and impact of interventions

“…Combined with our counterfactual analysis of restricting visits (Figure 6) this suggests that reducing infection levels in care home residents is challenging. This highlights the difficulty of protecting care home residents from COVID-19: due to the necessarily close contact between staff and residents within a care home, once a care home outbreak has begun it is very difficult to reduce transmission, which overrides any impact of reducing the number of introductions ( 21, 22 ).…”