The association between age, COVID-19 symptoms, and social distancing behavior in the United States

  1. David Canning
  2. Mahesh Karra
  3. Rashmi Dayalu
  4. Muqi Guo
  5. David E. Bloom

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Abstract

Background

Public health authorities recommend that people practice social distancing, especially if they have symptoms of coronavirus disease (COVID-19), or are older and more at risk of serious illness if they become infected. We test the hypothesis that these groups are following these recommendations and are more likely to undertake social distancing.

Methods

We conducted an open online survey of 4,676 U.S. adults aged 18 and older between April 4 and April 7, 2020. We model the effects of age and common COVID-19 symptoms in the last two weeks on going out of the home for non-healthcare reasons the day before taking the survey, using a logistic model and the number of close contacts (within 6 feet) that respondents had with non-household members, using a Poisson count model. Our models control for several covariates, including other flu-like symptoms, sex, education, income, whether the respondent worked in February, household size, population density in the respondent’s ZIP code, state fixed effects, and the day of completion of the survey. We also weight our analyses to make the sample representative of the U.S. adult population.

Findings

About 52 percent of the adult United States population went out of their home the previous day. On average, adults had close contact with 1.9 non-household members. We find that having at least one COVID-19 symptom (fever, dry cough, or shortness of breath) increased the likelihood of going out the previous day and having additional close contacts with non-household members; however, the estimates were not statistically significant. When disaggregating our analysis by COVID-19 symptoms, we find no strong evidence of greater social distancing by people with a fever or cough in the last two weeks, but we do find that those who experienced shortness of breath have fewer close contacts, with an incidence rate ratio (IRR) of 0.49 (95% CI: 0.30–0.78). Having other flu-like symptoms reduces the odds of going out by 0.32 (95% CI: 0.18–0.60) and the incidence rate of having close contacts by 42 percent (IRR = 0.58; 95% CI: 0.38–0.88). We find that older people are just as likely to leave their homes as younger people, but people over the age of 50 had less than half the predicted number of close contacts than those who were younger than 30. Our approach has the limitation that the survey sample is self-selected. Our findings may therefore be subject to selection bias that is not adequately controlled for by weighting. In addition, the possibility exists of confounding of the results due to omitted variable bias.

Conclusions

We provide evidence that older people are having significantly fewer close contacts than younger people, which is in line with the public health authorities’ recommendations. We also find that people experiencing shortness of breath are practicing more intense social distancing. However, we find that those with two other common COVID-19 symptoms, fever and dry cough, are not engaging in greater social distancing, suggesting that increased targeting on relevant symptoms, and messaging, may be required.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.19.20065219: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Our study has several limitations. One limitation is our measures of symptoms. Some of the symptoms of we measure may be chronic, and people may know that these symptoms are not related to COVID-19, and so may not be social distancing. Additionally, two weeks may be too long of a time frame; people may reduce their social distancing behavior only for a short while after symptoms end. A new study with greater temporal resolution of the timing of symptoms, which could control for chronic versus recent onset of symptoms, would be useful. The selectivity of our sample is also an issue. A survey with greater balance of respondent characteristics would be desirable so that we do not have such extreme weights on some subgroups. Ideally, the sample would be a random sample of the population so that representativeness would be likely without the need to weight. Our results may also be confounded by the fact that people who go out a lot are more likely to get symptoms of COVID-19, and this may lead to the positive association between symptoms and going out that we observe. We measure the symptoms over the last two weeks and going out only the day before, so this temporal ordering suggests that the causality runs from symptoms to going out, rather than vice versa. However, the possibility exists of unobserved individual characteristics that are not controlled for in our analysis that affect both going out and getting COVID-19 symptoms. This unobserved heterogeneity could be addressed th...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    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.

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  2. Version published to 10.1101/2020.04.19.20065219 on medRxiv