Discussion
The proportion of foreign-born respondents who had only been vaccinated abroad was 3 %. More than half of these (52 %) had reported it to the Norwegian health service. Although the respondents state that they reported their immunisation to the Norwegian health service, it is uncertain whether this was actually registered by healthcare personnel in SYSVAK and consequently included in the vaccine statistics. However, the extent of such post-registration in SYSVAK will not change the conclusion we can draw from our results. According to the official vaccine statistics, the gap in vaccine coverage between Norwegian-born (94 %) and foreign-born (76 %) persons is 18 percentage points (2). The fact that 3 % of foreign-born persons have been vaccinated abroad only explains a fraction of this difference.
The results may be impacted by the representativeness of the sample. The survey has some known biases, which are described elsewhere (8). Among other things, younger men are underrepresented, as are men in general, while people with a high level of education are overrepresented. In Viken, 17 % of the adult population was born abroad, compared to 12 % in our sample. The proportion who stated that they had been vaccinated in our survey is far higher than for similar groups at a national level in SYSVAK at the time of the survey (Table 2) (9). This may indicate a sampling bias among both Norwegian-born and foreign-born persons. Being over a certain age and a higher education are both associated with a greater willingness to be vaccinated (7). The skewed selection of foreign-born persons in the sample is also probably related to how well they are integrated, since the survey was only in Norwegian and required access to the BankID system. This may have led to an overestimation of vaccination abroad since the sample of foreign-born persons appears to show a high level of willingness to be vaccinated. However, it may be that the most integrated foreign-born persons are more likely to have been vaccinated in Norway, and that we have therefore underestimated the proportion of foreign-born persons vaccinated abroad.
Table 2
Compilation of vaccination coverage (%) for the first dose of the coronavirus vaccine among participants in the public health survey conducted in Viken in November 2021, and in the general population as reported in the Norwegian Institute of Public Health's weekly report for the period 8–14 November (9).
| Country of birth | Viken (self-reported) | SYSVAK (9)1 |
|---|
| Norway | 98 | 91 |
| Abroad | 93 | 76 |
| Poland | 83 | 40 |
| Lithuania | 74 | 41 |
| Latvia | 76 | 38 |
We have highlighted Poland, Lithuania and Latvia in particular because these countries constitute large immigrant groups, are geographically close to Norway, have low vaccine coverage and are relatively well represented in the dataset. Among these groups, a higher proportion had only been vaccinated abroad, but not to the extent that this explains the difference in vaccination coverage between persons born in these countries and those born in Norway.
The survey is from Viken, and whether the results can be generalised to the whole of Norway is uncertain. Additionally, Viken is Norway's largest county (home to 23 % of the population), and the variation in vaccination coverage between counties is small (4 percentage points difference between the highest and lowest) (2).