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New Paper (Other): Changes in contact patterns shape the dynamics of the COVID-19 outbreak in China #299

Open dziakj1 opened 4 years ago

dziakj1 commented 4 years ago

Title: Changes in contact patterns shape the dynamics of the COVID-19 outbreak in China

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Please paste a link to the paper or a citation here:

Link:

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Citation: @doi:10.1126/science.abb8001

Is this paper primarily relevant to Background or Pathogenesis?

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dziakj1 commented 4 years ago

Summary

J. Zhang et al., Science (2020)

Suggested questions to answer about each paper:

They analyzed data from questionnaires and contact surveys in Wuhan, as well as in Shanghai (a much larger city) as a comparison.

One of the aspects of the analysis was simply to estimate, based on retrospective self-report, how many daily contacts people had before and after the social distancing measures were required.
Another analysis was somewhat more interesting. "Briefly, all close contacts of COVID-19 cases reported in Hunan province were placed under medical observation for 14 days and were tested using real-time RT-PCR. Those who tested positive were considered as SARS-CoV-2 infections." Based on this, they created an age-dependent SIR transmission model.

This is about COVID-19.

Social distancing was effective: "Daily contacts were reduced 7-8-fold during the COVID-19 social distancing period, with most interactions restricted to the household." According to their transmission model, "social distancing alone, as implemented in China during the outbreak, is sufficient to control COVID-19. While proactive school closures cannot interrupt transmission on their own, they can reduce peak incidence by 40-60% and delay the epidemic."

Infection rates depended on age: "children 0-14 years are less susceptible to SARS-CoV-2 infection than adults 15-64 years of age (odds ratio 0.34, 95%CI 0.24-0.49), while in contrast, individuals over 65 years are more susceptible to infection (odds ratio 1.47, 95%CI: 1.12-1.92)... These findings are in contrast with a previous study in Shenzhen, where susceptibility to infection did not change with age..." This result was somewhat surprising to me, since I had heard many times that senior citizens were more likely to become ill upon infection than children were, but I had not heard about children also possibly being less likely to be infected at all. I would have assumed that this was just measurement bias due to asymptomatic cases going undetected, but supposedly they had objective tests for everybody, whether symptomatic or not."

I am not really sure. The finding that there were fewer daily contacts with other people during lockdown than before lockdown is rather trivial, although it would have been troubling if it had not been found. The early data from China is of some historical interest, but China is no longer the epicenter of the pandemic. The age-dependent infection susceptibility seems to be the most interesting finding, if it can be replicated.

The contacts survey in Wuhan was self-reported and was also subject to recall bias when asking about the number of contacts in a pre-pandemic day. They appear to have somewhat more reliable data for Shanghai, although still self-report and still subject to social desirability bias (possible underreporting of contacts during lockdown).