A new method for near real-time, nationwide surveillance of nosocomial COVID-19 in Norway: providing data at all levels of the healthcare system, March 2020 to March 2022.

BackgroundGreat efforts have been made to minimise spread and prevent outbreaks of COVID-19 in hospitals. However, there is uncertainty in identifying nosocomial vs community-acquired infections. To minimise risks and evaluate measures, timely data on infection risk in healthcare institutions are required.AimsTo design an automated nationwide surveillance system for nosocomial COVID-19 using existing data to analyse the impact of community infection rates on nosocomial infections, to explore how changes in case definitions influence incidence and to identify patients and wards at highest risk and effects of SARS-CoV-2 variants.MethodsWe used data from the Norwegian real-time emergency preparedness register (Beredt C19), which includes all patients nationwide admitted to Norwegian hospitals between March 2020 and March 2022 with a positive SARS-CoV-2 PCR test during their hospital stay or within 7 days post-discharge. COVID-19 cases were assigned to categories depending on the time between admission and testing.ResultsInfection rates for definite/probable nosocomial COVID-19 increased from 0.081% in year 1 to 0.50% in year 2 in hospital admissions 7 days or longer. Varying the definitions resulted in large changes in registered nosocomial infections. Infection rates were similar across different ward types. By 2022, 58% of patients with a definite/probable nosocomial infection had received three vaccine doses.ConclusionAutomated national surveillance for nosocomial COVID-19 is possible based on existing data sources. Beredt C19 provided detailed information with only 5% missing data on hospitals/wards. Epidemiological definitions are possible to standardise, enabling easier comparison between regions and countries.

Transmission of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) between hospital workers and members of their household: Nationwide, registry-based, cohort study from Norway.

BACKGROUND: Understanding and limiting infection in healthcare workers (HCWs) and subsequent transmission to their families is always important and has been underscored during the COVID-19 pandemic. Except in specific and local settings, little is known about the extent of such transmissions at the national level. OBJECTIVE: To describe SARS-CoV-2 infection in HCWs and to estimate the risk of HCWs transmitting COVID-19 to their household members, including calculating the secondary attack rate to household members and estimating the risk for hospital workers to contract COVID-19 at home. METHODS: Using individual-level data on all HCWs employed in Norwegian hospitals and their household members, we identified (1) the number of HCWs who tested positive for SARS-CoV-2 between August 2020 and September 2021 and the proportion of those who were index cases in their own household and (2) the number of HCWs who were secondary cases in their own households. RESULTS: During this period, ∼3,005 (2,6%) hospital workers acquired COVID-19. Almost half of all hospital workers with confirmed COVID-19 were likely index cases in their own households. When the index case in a family was an HCW, the secondary attack rate was 24.8%. At least 17.8% of all confirmed COVID-19 cases among hospital workers were acquired in the household. CONCLUSIONS: Our results suggest not only that many HCWs are infected with SARS-CoV-2 in their households but also that infected HCWs constitute a serious infection risk to members of the HCW's household.