Covid-19 among persons born outside Norway, adjusted for occupation, Household crowding, medical risk group, education and income
Report
|Published
Previous studies from Norway show that rates of confirmed infection with SARS-CoV-2 and related hospital admissions have been higher among people born outside of Norway comparted to those born in Norway.
Summary
| Correction: An additional figure (figure 7) has been added to this report. Figure 7 is a duplicate of Figure 6, and the figure text in Figure 7 is thus misleading, since the text refers to overcrowding and COVID-19 admissions and not overcrowding and COVID-19 infection as the figure shows. We have chosen not to publish a correction to the report since the figures for admissions by overcrowding and country of birth are too small. |
Introduction
Previous studies from Norway show that rates of confirmed infection with SARS-CoV-2 and related hospital admissions have been higher among people born outside of Norway comparted to those born in Norway. Greater knowledge about how infection and disease due to SARS-CoV-2, the virus that causes COVID-19, is distributed in different parts of the population is essential for effective implementation of containment and mitigation strategies during the pandemic; to ensure fewest possible become seriously ill or die of COVID-19, and to contribute to the reduction of health disparities. The Norwegian Institute of Public Health has a responsibility and duty to provide knowledge so that decision-makers on the national and municipal level can target mitigation strategies toward the most affected and exposed groups with regard to infection, serious disease and death.
Methods
The BeredtC19 Register is a national emergency preparedness register established to monitor infection and the use of health services in Norway during the COVID-19 pandemic. BeredtC19 consists of individual-level data, covering the entire Norwegian population and includes information on country of birth. We have examined PCR-confirmed infections and hospital admissions with COVID-19 for i) persons born outside of Norway, ii) persons born in Norway to foreign-born parents, and iii) the remaining population, that is, persons born in Norway to Norwegian-born parents. The foreign-born group was divided into the 25 birth-countries with most residents in Norway. We compared the proportion of individuals infected and hospitalized among these groups with regression models adjusted for age, sex, municipality of residence, occupation, overcrowded housing (overcrowding), education, household income and medical risk group for severe COVID-19. We have studied the period from 15 June 2020, because from this date there were low rates of infection and wide access to testing, until 31 March 2021.
Results
Confirmed infections and hospital admissions related to COVID-19 among persons born outside Norway are, relative to the number in this group, higher than in the rest of the population. Among foreign-born persons 3140 per 100 000 had confirmed infection, among Norwegian-born with two foreign-born parents 4799 per 100 000 had confirmed infection, and in the remaining population (Norwegian-born with Norwegian-born parents) 1011 per 100 000 had confirmed infection. The corresponding rates for hospitalizations are respectively: 147 per 100 000, 47 per 100 000, and 37 per 100,000.
The proportions, per 100 000, with confirmed infection have been highest among people born in Pakistan (9173), Somalia (8477) and Iraq (7397). Three of the countries included in the sample have lower proportions of infection than Norwegian-born persons; China (855), Germany (1078) and Denmark (1132).
The proportion (per 100 000) of people in the group who have been admitted with COVID-19 has been particularly high among people born in Pakistan (898), Iraq (449), Turkey (402) and Somalia (382). Some foreign-born groups have particularly low proportions of admissions for COVID-19; USA (14), Lithuania (16), Latvia (25), and Sweden (29) and China (30).
Our findings show that factors related to social inequality individually are risk factors for infection and/or hospitalization with COVID-19. This applies to both Norwegian-born and foreign-born persons. However, these factors still do not fully explain the differences in the proportions of infected and hospitalized for people with different country backgrounds. Adjusting for age, sex and municipality of residence explains about 21% of the overrepresentation in confirmed infections among foreign-born compared to Norwegian-born, and about 6% of overrepresentation in admissions. Municipality of residence explains the most. Occupation, overcrowding, medical risk group, education and household income explain relatively little of the differences in infection and hospitalizations between foreign-born and Norwegian-born persons. After adjusting for these factors in addition to age, sex and municipality, the overrepresentation we observe was reduced by about 12% for confirmed infections and 3% for admissions; that is, a reduction from 1686 to 1490 per 100 000 for infection, and from 103 to 101 per 100 000 for admissions.
Regarding test activity, we find little underrepresentation among foreign-born persons and Norwegian-born with foreign-born parents, but a very large overrepresentation in the proportion of those tested who test positive. While just over 2% test positive of those tested among Norwegian-born with Norwegian-born parents, this figure is as high as 11% for Norwegian-born with foreign-born parents, and 7% for foreign-born persons.
Discussion
This report confirms that factors related to social inequality, overcrowding and medical risk group are key mechanisms for COVID-19 infection and serious disease. However, this report also shows that these conditions still only explain some of the differences in infection and hospitalization between people with different country backgrounds. Social inequality, overcrowding and medical risk group explain differences within each country of birth, but do not explain why the level of infection and hospitalization is so much higher for some countries of birth. The most obvious explanation for high hospitalization rates in many of the groups is that the infection rate (detected and undetected) is higher in these groups. This is supported by the fact that, despite low, and recently no, underrepresentation in testing, there are high proportions among the tested who test positive in many of the groups where the admission numbers are highest.
The data used in our analyses are crude and only capture formally registered information, whether it is overcrowding, occupation, household income, education or medical risk. It is not certain that the way these variables have been defined in our analyses is best suited to detect underlying differences in infection risk. There are other factors that indicate that our estimates should be interpreted with caution, but the main pattern still appears robust.
The overrepresentation we observe may be due to a combination of a number of factors that are difficult to capture. Some of these may be related to differences in travel patterns, differences in how well the test-isolate-trace-and-quarantine (TISK) strategy works among different groups, how infection spreads within a social environment and other complex interactions between different conditions. The TISK strategy is dependent on all individuals having good access to testing, having high confidence in the contact tracing team, and that regulations and orders for quarantine and isolation are followed. Language, access to electronic identification for signing into secure websites, and many other factors can be barriers that make it more difficult for individuals to be tested. Financial conditions, such as worrying about loss of income for those without permanent jobs or the right to sick pay, can also be barriers to testing and staying at home. Persistently high infection rates in some districts or municipalities may have led to a negative spiral where high workload on the contact tracing teams creates delays in contact tracing, in turn giving a higher risk that chains of infection are not broken. This may also have been exacerbated by language difficulties. Although much has been done to adapt and disseminate information, it is still the case that local regulations, and changes in guidelines and advice, are complicated information that changes rapidly. This can be challenging for all and will be especially challenging for people who do not master Norwegian.
Infection tracing data indicate that much of the spread of infection occurs within families. It is therefore of utmost importance to have more knowledge about how chains of infection can be broken within crowded environments and within families. It is also important to have more knowledge about how infection is introduced into different environments in Norway, including the significance of via travellers from abroad.
Serious disease and death due to COVID-19 have long affected some immigrant groups far more severely than the rest of the population. Nevertheless, it is still the case that the vast majority have not been infected with COVID-19, and this applies to both Norwegian-born and foreign-born individuals. It is also the case that during periods where infection rates have been reduced, they have also been reduced among foreign-born (Folkehelseinstituttet 2021c).
Conclusion
Foreign-born persons as a group are significantly overrepresented among those with confirmed infection and among those admitted with COVID-19. The overrepresentation in confirmed infections and hospitalizations decreases somewhat when we adjust for age, sex, and municipality of residence, but still remains high. The overrepresentation in both confirmed infections and hospitalizations changes only to a small degree after we in addition adjust for socio-economic conditions such as income, education and overcrowding. Nor does the adjustment for medical risk between different groups affect the overrepresentation to any great degree. When we adjust for all these factors together, it has a certain effect, but the overrepresentation among foreign-born is still significant. The reasons for the overrepresentation among different parts of the immigrant population can thus not be explained with the data we have had available in this report. It is important to gain more knowledge about the potential causes of the overrepresentation, including any associations with lack of or delayed access to health services (including testing and contact tracing) and undetected infection in some groups.
