Final report from a one-year evaluation of notifiable diseases surveillance during the COVID-19 epidemic
A gradually implemented one-year evaluation has documented that the Norwegian Surveillance System for Communicable Diseases (MSIS) was robust enough to maintain its function during the COVID-19 epidemic.
- A gradually implemented one-year evaluation has documented that the Norwegian Surveillance System for Communicable Diseases (MSIS) was robust enough to maintain its function during the COVID-19 epidemic. This was made possible by extensive work to upgrade the system that was started before the pandemic and was intensified during its course.
- The surveillance system was flexible enough to accommodate the inclusion of a new disease in the list of notifiable diseases, which required more laboratory and human resources than all other notifiable diseases combined.
- The surveillance system stability was most affected in April-May 2020, following the inclusion of COVID-19 to the list, upscaling of the laboratory capacity for COVID-19 testing and the introduction of strict social distancing measures. After this first challenging period, however, the system's stability was restored.
- Less attention to diagnosing cases with mild symptoms has led to lower sensitivity and data quality in reporting from the primary healthcare. There was also reduced representativeness in reporting infectious diseases in some counties and among persons aged under 20 years.
- Completeness of MSIS reports was reduced during the COVID-19 epidemic in the primary healthcare, while reporting timeliness has overall improved, which can be attributed to the introduction of new reporting tools and improved user support.
- Of 145 physicians who participated in the MSIS user survey, 40 (28 %) replied that they do not always notify diagnosed cases to MSIS. There is a need to include reporting physicians more in the system and increase their sense of ownership by improving access to data and feedback from FHI experts.
On 30 January 2020, the World Health Organization declared the novel coronavirus outbreak a public health emergency of international concern (PHEIC). Since March 2020, the number of COVID-19 cases reported to the Norwegian Surveillance System for Communicable Diseases (MSIS) has exceeded the total number of other notifiable cases, with large regional differences. The main aim of this project was to evaluate the MSIS function during the COVID-19 epidemic in order to develop competence on how to ensure the system's robustness to withstand future crises.
The report summarizes a one-year project. It was initiated in April 2020, one month after the beginning of the epidemic and the introduction of comprehensive infection control measures. Between April 2020 and February 2021, we continued the evaluation by publishing periodic evaluation reports (www.fhi.no/publ/2020/covid-19-msis/). They were systematically expanded to include more surveillance attributes and aggregation levels. We have gradually included information from registers collecting data at different levels of the surveillance pyramid and independently from MSIS. We have also identified information gaps and conducted two investigations: a survey of diagnostic laboratories on test referral activity and survey of MSIS user experience during COVID-19. Methods and detailed results of these investigations are published in dedicated reports.
In this final report, we evaluate the MSIS function against attributes of an effective surveillance system defined in the European Centre for Disease Prevention and Control guideline. We have assessed the system's stability, acceptability and flexibility in summarizing periodic evaluation reports and results of both surveys. We have assessed the sensitivity, completeness of MSIS reports, timeliness and representativeness by comparing selected indicators of disease reporting at different levels of the surveillance pyramid. We have included indicators based on the data from MSIS, data on primary healthcare consultation from the Norwegian Directorate of Health (sKUHR), the Norwegian Patient Register (NPR), the event-based surveillance (Vesuv) and results from survey og diagnostic laboratories. We have grouped all notifiable diseases (with some exceptions) into five disease groups. We have described indicators by month, disease group and county and stratified by primary and specialist health services. To assess the effect of the COVID-19 epidemic, we have compared indicators during the epidemic (1 March - 31 December 2020) with the reference period (1 June 2019 - 29 February 2020).
Between April 2020 and February 2021, we published 17 periodic evaluation reports. We have documented a 33-71% reduction in reporting of other infectious diseases to MSIS compared with corresponding reporting periods. The reduction was most pronounced in the primary healthcare, among travel-related cases and vaccine-preventable diseases. Even though data quality was affected during the COVID-19 epidemic, it took less time to register reported cases in MSIS and the system's function was maintained. Almost one third of diagnosing physicians indicated that they do not always notify cases. Acceptability was lower among hospital specialists, among physicians with work experience less than 5 years and among physicians experiencing challenges with MSIS reporting. Both 30% of the physicians responding to our survey and 2 of 4 laboratories reported that laboratory testing for selected diseases were less available.
We assessed surveillance sensitivity in primary healthcare based on 18,389 cases reported to MSIS, 1,792,247 GP consultations for selected infectious diseases registered in sKUHR and 142,575 testing referrals from eight laboratories. The monthly incidence of reported cases was reduced by 54% during the COVID-19 epidemic, compared to the reference period. The reduction was highest in April (-70%) and May (-68%) compared with the median in the reference period. The median number of consultations per month decreased by 41% for respiratory infections and by 35% for gastrointestinal infections. Consultations for gastrointestinal infections were most reduced in April 2020 (-53%). The median number of referrals for laboratory testing decreased by 30% during the COVID-19 epidemic and was reduced most in April 2020 (-54%). The highest reduction in consultations and reported incidence was in Oslo, Vestland and Vestfold and Telemark.
We assessed surveillance sensitivity in the specialist healthcare based on 10,902 cases reported to MSIS, 23,653 hospital admissions registered in NPR and 60,610 testing referrals from eight laboratories. The incidence of reported cases was reduced by 27 % during the COVID-19 epidemic, compared to the reference period. The reduction was highest in April (-54 %) and May (-45 %) compared with the median in the reference period. The median number of admissions decreased by 17 %, while the discrepancy between the number of cases registered in NPR and reported to MSIS with corresponding ICD-10 codes has increased from –66 % in December 2019 to –80 % in May 2020. The median number of referrals for laboratory testing was almost unchanged (- 3 %) and was most reduced in April 2020 (-20 %). The highest reduction in admissions for notifiable diseases registered in NPR, reported to MSIS and the highest increase in the discrepancy between registered in NPR and reported to MSIS was seen in Vestfold and Telemark, Nordland and Møre og Romsdal.
Between June 2019 and December 2020, there were 259 outbreaks other than COVID-19 notified to Vesuv. Of these, only 14 (5 %) were registered in MSIS. The frequency of reported outbreaks decreased by 50 % during the COVID-19 epidemic. Highest reduction was for vaccine-preventable diseases, diseases caused by resistant bacteria and other non-notifiable diseases. Highest reduction in the frequency of reported outbreaks was in Oslo, Vestland and Vestfold and Telemark.
We have assessed the completeness of 29,291 MSIS notifications. The completeness of eight key variables was more reduced during the COVID-19 epidemic in primary healthcare (74% vs. 80% in the reference period) than from specialist healthcare (78% vs. 79%). Completeness decreased most for notifications of food and waterborne diseases from primary healthcare (78% vs. 86%), and for notifications of vaccine-preventable diseases from specialist healthcare (72% vs. 79%). Completeness decreased most in primary healthcare in Trøndelag and Rogaland, while in the specialist healthcare in Agder.
The total median time between symptom onset and updating of clinical information was reduced during the COVID-19 epidemic (31 days vs. 38 days in the reference period). The reduction was highest for food- and water-borne diseases (23 vs. 34 days) and lowest for vaccine-preventable diseases (39 vs. 41 days). The median time between symptom onset and specimen collection (n = 12,908 notifications) remained unchanged in both the primary (7 days) and specialist healthcare (3 days). The median time between specimen collection and registration (n = 29,245) was reduced in both the primary (5 vs. 6 days) and specialist healthcare (4 vs. 6 days). The median time between registration and updating of key information (n = 26,027) was also reduced in both the primary (19 vs. 23 days) and specialist healthcare (23.5 vs. 33 days). Total reporting timeliness was most improved in Trøndelag (12 days from onset to update vs. 22 days in the reference period), Innlandet (14 vs. 30 days), Nordland (14 vs. 20 days) and Troms and Finnmark (17 vs. 22 days).
Reporting to MSIS was most reduced for age groups under 20 years and 40-59 years and least among people aged 60 years or older. There were large differences in the reported incidence of notifiable diseases in people with a country of birth outside Norway.
We have documented that MSIS maintained its function during the COVID-19 epidemic. The reduction in MSIS reporting can be attributed to a large degree to the changing epidemiology of infectious diseases due to reduced international travel and less contact between people. The highest reduction in the incidence of vaccine-preventable diseases can be attributed to infections that are transmitted through droplet infection or via direct contact. Overall, testing for notifiable diseases was maintained. The timeliness of the system was improved, which is related to the extensive upgrade of MSIS in recent years.
However, surveillance sensitivity was reduced in primary healthcare, since fewer suspected cases with milder symptoms have been referred for laboratory testing. Sensitivity was reduced to a different degree in different counties and different age groups. The high incidence of COVID-19 may lead to strengthened social distancing measures, which could reduce the incidence of other infectious diseases, but may also lead to less attention given to diagnosing of other infections. The MSIS sensitivity and data quality were most affected in April-May 2020, following the addition of COVID-19 to the list of notifiable diseases, upscaling of the laboratory capacity for testing and the introduction of strict control measures. After the first challenging period, however, the system's stability was re-established and was not significantly affected during the large increase in COVID-19 incidence and strict infection control measures implemented in October-December 2020.
This one-year evaluation has documented that MSIS maintained its function during the COVID-19 epidemic. It was flexible enough to accommodate the inclusion of a new disease in the list of notifiable diseases, which required more laboratory and human resources than all other notifiable diseases combined. After the first challenging period, the stability of the system was restored. Although most of the reduced reporting of infectious diseases can be attributed to less travel and social distancing control measures, we have documented that surveillance sensitivity has been affected, especially in primary healthcare. The system has not been able to reliably measure changes in the disease burden during the COVID-19 epidemic in all counties and in all age groups in a representative way. FHI must continue to work to improve physicians' participation in the system by improvement the access to data, providing support and feedback that is useful in physicians’ daily work. We also recommend to evaluate surveillance systems in a more systematic manner.