Dynamics of non-household contacts during the COVID-19 pandemic in 2020 and 2021 in the Netherlands

Backer, J.A.; Bogaardt, Laurens; Beutels, Philippe; Coletti, Pietro; Edmunds, W. John; Gimma, Amy; Hagen, Cheyenne C. E. van; Hens, Niel; Jarvis, Christopher; Vos, Eric R. A.; Wambua, James; Wong, Denise; Zandvoort, Kevin van; Wallinga, Jacco

doi:10.1038/s41598-023-32031-7

Cited by 16 publications

(11 citation statements)

References 33 publications

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“…The PiCo survey was held three times per year among a representative sample of the population in the Netherlands [3,39]. The CoMix survey was held every two weeks on a selected internet panel [40,41]. The 70+ participants in the PiCo and CoMix surveys reported 2.3 (2.1 - 2.5) (mean and 95% bootstrap CI) and 2.5 (2.0 - 3.1) contacts per day around survey period 1 and 5.1 (4.7 - 5.5) and 4.8 (2.1 - 10.2) contacts per day around survey period 2.…”

Section: Discussionmentioning

confidence: 99%

Contact patterns of older adults with and without frailty in the Netherlands during the COVID-19 pandemic

Backer

Kassteele

Fakiri

et al. 2023

Preprint

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Background During the COVID-19 pandemic social distancing measures were imposed to protect the population from exposure, especially elderly and frail persons who have the highest risk for severe outcomes. These restrictions greatly reduced contacts in the general population, but little is known about behaviour changes among elderly and frail persons themselves. Our aim was to quantify how COVID-19 measures affected contact behaviour of elderly and how this differed between frail and non-frail elderly. Methods In 2021 a contact survey was carried out among persons aged 70 years and older in the Netherlands. A random sample of persons per age group (70-74, 75-79, 80-84, 85-89, 90+) and gender was invited to participate, either during a period with stringent (April 2021) or moderate (October 2021) measures. Participants provided general information on themselves including their frailty, and reported characteristics of all persons with whom they had face-to-face contact on a given day, over the course of a full week. Results In total 720 community-dwelling elderly persons were included (overall response rate of 15%), who reported 16,505 contacts. During the survey period with moderate measures, non-frail participants had significantly more contacts outside their household than frail participants. Especially for women, frailty was a more informative predictor for number of contacts than age. During the survey period with stringent measures, frail and non-frail participants had significantly lower numbers of contacts compared to the survey period with moderate measures. The reduction of number of contacts was largest for the eldest non-frail participants. As they likely interact closely with highly aged and highly frail persons, this reduction of number of contacts indirectly protects frail elderly from SARS-CoV-2 exposure. Conclusions The results of this study reveal that social distancing measures during the COVID-19 pandemic differentially affected the contact patterns of frail and non-frail elderly. The reduction of contacts may have led to direct protection of elderly persons in general but also to indirect protection of frail elderly.

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Section: Discussionmentioning

confidence: 99%

Contact patterns of older adults with and without frailty in the Netherlands during the COVID-19 pandemic

Backer

Kassteele

Fakiri

et al. 2023

Preprint

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“…All analyses are performed in R version 4.1.3 25 using the mgcv package 26 with family ocat for ordered categorical variables. Code is available on Github 27 , and data is published on Zenodo 28 in the standardised format of socialcontactdata . org .…”

Section: Methodsmentioning

confidence: 99%

“…The datasets analysed in the current study are available in the Zenodo repository (https://doi.org/10.5281/zenodo.4790347) 28 under CC BY 4.0 license.…”

Section: Data Availabilitymentioning

confidence: 99%

Dynamics of non-household contacts during the COVID-19 pandemic in 2020 and 2021 in the Netherlands

Backer

Bogaardt

Beutels

et al. 2022

Preprint

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The COVID-19 pandemic was in 2020 and 2021 for a large part mitigated by reducing contacts in the general population. To monitor how these contacts changed over the course of the pandemic in the Netherlands, a longitudinal survey was conducted where participants reported on their at-risk contacts every two weeks, as part of the European CoMix survey. The survey included 1659 participants from April to August 2020 and 2514 participants from December 2020 to September 2021.We categorized the number of unique contacted persons excluding household members, reported per participant per day into six activity levels, defined as 0, 1, 2, 3-4, 5-9 and 10 or more reported contacts. After correcting for age, vaccination status, risk status for severe outcome of infection, and frequency of participation, activity levels increased over time, coinciding with relaxation of COVID-19 control measures.

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“…Face-to-face and physical contacts between members of different households were to be reduced, as each contact could be an at-risk event for transmission. Many contact surveys that were conducted during the pandemic showed that more stringent COVID-19 measures indeed lead to lower contact rates [1][2][3][4][5][6][7][8]. Most contact-reducing measures were lifted shortly after the emergence of the more transmissible Omicron variants of SARS-CoV-2 in late 2021.…”

Section: Introductionmentioning

confidence: 99%

Contact behaviour before, during and after the COVID-19 pandemic in the Netherlands: evidence from contact surveys in 2016-2017 and 2020-2023

Backer,

Vos,

den Hartog

et al. 2024

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Background The first wave of the COVID-19 pandemic in 2020 was largely mitigated by reducing contacts in the general population. In 2022 most contact-reducing measures were lifted. Aim We assess whether the population has reverted to pre-pandemic contact behaviour and how this would affect the transmission potential of a newly emerging pathogen. Methods The PIENTER Corona study was held every 2-6 months in the Netherlands from April 2020, as a follow-up on the 2016-2017 PIENTER3 study. In both studies, participants (ages 1-85) reported the number and age group of all face-to-face persons contacted on the previous day. The contact behaviour during and after the COVID-19 pandemic was compared to the pre-pandemic baseline. Results We found an average of 15.2 (13.3-16.9, 95% CI) community contacts per person per day in the post-pandemic period, which is 14% lower than the baseline value of 17.6 (16.3-18.9). Children have the highest number of contacts as before the pandemic. Mainly adults aged 20-59 have not reverted to their pre-pandemic behaviour, possibly because this age group works more often from home. Although the number of contacts is structurally lower compared to the pre-pandemic period, the effect on the potential spread of a newly emerging respiratory pathogen is limited if all age groups were equally susceptible. If younger age groups were less susceptible, as observed during the first COVID-19 wave, the transmission potential as well as the required control effort would be lower. Conclusion Continuous monitoring of contacts is needed to be prepared for a future pandemic.

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Dynamics of non-household contacts during the COVID-19 pandemic in 2020 and 2021 in the Netherlands

Cited by 16 publications

References 33 publications

Contact patterns of older adults with and without frailty in the Netherlands during the COVID-19 pandemic

Contact patterns of older adults with and without frailty in the Netherlands during the COVID-19 pandemic

Dynamics of non-household contacts during the COVID-19 pandemic in 2020 and 2021 in the Netherlands

Contact behaviour before, during and after the COVID-19 pandemic in the Netherlands: evidence from contact surveys in 2016-2017 and 2020-2023

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