Time trends in social contacts of individuals according to comorbidity and vaccination status, before and during the COVID-19 pandemic
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Abstract
Background
As we are confronted with more transmissible/severe variants with immune escape and the waning of vaccine efficacy, it is particularly relevant to understand how the social contacts of individuals at greater risk of COVID-19 complications evolved over time. We described time trends in social contacts of individuals according to comorbidity and vaccination status before and during the first three waves of the COVID-19 pandemic in Quebec, Canada.
Methods
We used data from CONNECT, a repeated cross-sectional population-based survey of social contacts conducted before (2018/2019) and during the pandemic (April 2020 to July 2021). We recruited non-institutionalized adults from Quebec, Canada, by random digit dialling. We used a self-administered web-based questionnaire to measure the number of social contacts of participants (two-way conversation at a distance ≤2 m or a physical contact, irrespective of masking). We compared the mean number of contacts/day according to the comorbidity status of participants (pre-existing medical conditions with symptoms/medication in the past 12 months) and 1-dose vaccination status during the third wave. All analyses were performed using weighted generalized linear models with a Poisson distribution and robust variance.
Results
A total of 1441 and 5185 participants with and without comorbidities, respectively, were included in the analyses. Contacts significantly decreased from a mean of 6.1 (95%CI 4.9–7.3) before the pandemic to 3.2 (95%CI 2.5–3.9) during the first wave among individuals with comorbidities and from 8.1 (95%CI 7.3–9.0) to 2.7 (95%CI 2.2–3.2) among individuals without comorbidities. Individuals with comorbidities maintained fewer contacts than those without comorbidities in the second wave, with a significant difference before the Christmas 2020/2021 holidays (2.9 (95%CI 2.5–3.2) vs 3.9 (95%CI 3.5–4.3); P <0.001). During the third wave, contacts were similar for individuals with (4.1, 95%CI 3.4–4.7) and without comorbidities (4.5, 95%CI 4.1–4.9; P =0.27). This could be partly explained by individuals with comorbidities vaccinated with their first dose who increased their contacts to the level of those without comorbidities.
Conclusions
It will be important to closely monitor COVID-19-related outcomes and social contacts by comorbidity and vaccination status to inform targeted or population-based interventions (e.g., booster doses of the vaccine).
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SciScore for 10.1101/2021.12.02.21267205: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The CONNECT study was approved by the ethics committee of the CHU de Québec research center and all participants gave their consent to participate in the study during the recruitment phone call.
Consent: The CONNECT study was approved by the ethics committee of the CHU de Québec research center and all participants gave their consent to participate in the study during the recruitment phone call.Sex as a biological variable not detected. Randomization Then, we used an age-stratified probability sampling to randomly select one individual per household to participate in CONNECT. Blinding not detected. Power Analysis For example, with a sample size of 1200 individuals, 22% of which having … SciScore for 10.1101/2021.12.02.21267205: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The CONNECT study was approved by the ethics committee of the CHU de Québec research center and all participants gave their consent to participate in the study during the recruitment phone call.
Consent: The CONNECT study was approved by the ethics committee of the CHU de Québec research center and all participants gave their consent to participate in the study during the recruitment phone call.Sex as a biological variable not detected. Randomization Then, we used an age-stratified probability sampling to randomly select one individual per household to participate in CONNECT. Blinding not detected. Power Analysis For example, with a sample size of 1200 individuals, 22% of which having comorbidities, it is possible to detect a difference of 0.9 contact (3.0 vs 3.9) with 85% power and 5% two-tailed type I error, taking into account a design effect of 5 due to overdispersion and correlation between days (Appendix Table A3). Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Our study has some limitations. First, although CONNECT participants were randomly recruited from the Quebec general population, it is possible that individuals who agreed to participate in the study were more likely to adhere to physical distancing measures aiming to limit social contacts. However, we recruited a large sample of over 6600 participants, and we validated that they were generally representative of the Quebec population in terms of age, sex, region, household composition, ethnicity, and vaccination coverage. 32,42 Second, social desirability bias may have led to underreporting of social contacts. Indeed, because physical distancing measures limited social contacts during the pandemic, some participants may have been reluctant to report all their contacts, especially those not allowed by physical distancing measures. Nevertheless, all questions were identical for participants with and without comorbidities and they remained the same from the pre-pandemic period until the end of the study. Moreover, we ensured that the few added questions related to COVID-19 were asked at the end of the questionnaire to avoid influencing contact reporting. Third, comorbidities were self-reported, but we are confident that the most significant comorbidities lasting at least 6 months and for which there were symptoms or medications in the last 12 months were identified. Additionally, the most common comorbidities we identified (chronic lung disease, diabetes, hypertension, chronic h...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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