Border measures, implemented to interrupt between-country COVID-19 transmission, impacts border region residents.

Cross-border mobility (i.e., visiting cross-border family/friends) was not associated with SARS-CoV-2 seropositivity.

Cross-border measures did not substantially contribute to SARS-CoV-2 transmission in the Netherlands.

Border measures were implemented in many countries as infection prevention measures to interrupt between-country COVID-19 transmission. Border closings impact border region residents, as their professional and social lives are often intertwined across national borders. We studied whether crossing borders to visit family/friends in neighbouring countries (cross-border mobility) was associated with SARS-CoV-2 seroprevalence in Dutch Euregional residents.

SARS-CoV-2 serostatus (negative/positive) was assessed (pre-vaccination) using laboratory testing to determine previous infection. Visiting Belgian or German family/friends in February-March 2020 was questioned. The association between cross-border mobility and seroprevalence was tested using logistic regression analysis, adjusted for previously identified exposure factors.

In 9,996 participants, 36.8 % (n = 3,677) reported cross-border family/friends. Of these, one-third (n = 1,306) visited their cross-border family/friends in February-March 2020. Multivariable analyses revealed no positive association between cross-border mobility and seropositivity, for both participants living in a border municipality (ORfamily/friends not visited=0.90 [95 % CI:0.78–1.04], ORfamily/friends visited=0.88 [95 % CI:0.73–1.05]), and for participants not living in a border municipality (ORfamily/friends not visited=0.91 [95 % CI:0.72–1.16], ORfamily/friends visited=0.62 [95 % CI:0.41–0.94]).

This study provided no evidence of cross-border mobility as an important exposure factor for SARS-CoV-2. The results of our unique real-world study suggest that cross-border mobility did not substantially contribute to cross-border SARS-CoV-2 transmission in the Netherlands.

SARS-CoV-2

Seroprevalence

COVID-19

Cross-border mobility

Prevention and control

Transmission control

© 2024 The Authors. Published by Elsevier B.V.