New data on contact tracing effectiveness
Contact Tracing for Covid-19 — A Digital Inoculation against Future Pandemics
The most basic measures of the effectiveness of a pandemic response are case numbers and deaths. By these measures, South Korea’s response during its first wave of Covid-19 was highly successful. A key part of the South Korean contact-tracing system was digital contact-tracing technology. Evidence is emerging that [these systems] have been beneficial in identifying higher numbers of contacts per case than has traditional contact tracing, increasing the number of people with Covid-19 who have entered quarantine, shortening the time to quarantine by 1 to 2 days, and possibly preventing large numbers of infections thanks to downstream effects of augmented contact tracing.
Contact-tracing apps help reduce COVID infections, data suggest
[Nature news.] A pilot study of Spain’s Radar Covid app, conducted in the Canary Islands in July and published last month, found that the app notified roughly twice the number of people exposed to simulated infections, compared with manual contact tracing. Digital contact tracing is particularly effective at identifying contacts who don’t live together. Von Wyl and his team calculated that non-household contacts notified of exposure by the SwissCovid app entered quarantine a day earlier than did those notified through manual contact tracing. The NHS COVID-19 app also shortened the delay to quarantine by 1–2 days.
Optimal Lockdown Policy for Vaccination during COVID-19 Pandemic
In this paper, we study the relation between vaccination and lockdown policy and address the question on how to gradually relax the strength for the lockdown when vaccination is available. We extend the canonical epidemiological model SIR to find an optimal decision making with the aim to balance between economy and public health. Our results show that although vaccination can effectively reduce the deaths and infections caused by the COVID-19, lockdown is still necessary at the beginning of the vaccination rollout. The larger the infectious population, the more rigorous the optimal lockdown are required during vaccination.
Associations between changes in population mobility in response to the COVID-19 pandemic and socioeconomic factors at the city level in China and country level worldwide: a retrospective, observational study
We obtained anonymised daily mobile phone location data for 358 Chinese cities from Baidu, and for 121 countries from Google COVID-19 Community Mobility Reports. The reduction in intra-city movement intensity in China was stronger in cities with a higher socioeconomic index (SEI) than in those with a lower SEI (r=–0·47, p<0·0001). In the country-level analysis, countries with higher sociodemographic and Universal Health Coverage indexes had greater reductions in population mobility (ie, in transit stations, workplaces, and retail and recreation) following national emergency declarations than those with lower sociodemographic and Universal Health Coverage indexes. Although COVID-19 outbreaks are more frequently reported in larger cities, our analysis shows that future policies should prioritise the reduction of risks in areas with a low socioeconomic level—eg, by providing financial assistance and improving public health messaging.
Transmission Dynamics, Heterogeneity and Controllability of SARS-CoV-2: A Rural–Urban Comparison
Data included 1136 SARS-2-CoV infections of the rural outbreak in Hebei, China, and 135 infections of the urban outbreak in Tianjin, China. We reconstructed SARS-CoV-2 transmission chains and analyzed the effectiveness of vaccination and NPIs by simulation studies. The transmission of SARS-CoV-2 showed strong heterogeneity in urban and rural areas, with the dispersion parameters k = 0.14 and 0.35, respectively (k < 1 indicating strong heterogeneity). Although age group and contact-type distributions significantly differed between urban and rural areas, the average reproductive number (R) and k did not. Further, simulation results based on pre-control parameters (R = 0.81, k = 0.27) showed that in the vaccination scenario (80% efficacy and 55% coverage), the cumulative secondary infections will be reduced by more than half; however, NPIs are more effective than vaccinating 65% of the population.