New in @Nature: we used digital measurements for 7 million people exposed to confirmed COVID-19 cases to determine risks for virus transmission, captured well by @NHSCOVID19app. We found that number of hours of exposure is a major predictor, along with proximity. The 7 million people - ‘contacts’ - were contact traced by the @NHSCOVID19app. We analysed measurements of their risky exposure to a case linked to the later outcome of whether they reported a positive test in the app (unreported infections are missing). What did we find?

Our paper on the discovery of a new variant of HIV with heightened transmissibility and virulence is out today in Science science.org/doi/10.1126/sc… Teamwork from two consortia, and analysis led by
@ChrisWymant
1/n Nice perspective from Joel Wertheim putting the finding in broader context, especially COVID variants: "When viruses become more virulent" science.org/doi/10.1126/sc… 2/n

Thanks @BBCr4today to have me on this am to discuss how contact tracing and isolation might change to reflect increasing vaccination levels. Spoke alongside Mr Pitcher from @RevolutionBars who is worried about impact of @NHSCOVID19app on staff levels. Some take homes: ... 1/ People worried about what the @NHSCOVID19app does and doesn't do or recommend, can consult the FAQ faq.covid19.nhs.uk/category/?id=C… . 2/

Great thread, very informative. But not bearer of good news. This stands out to me as concerning:

https://twitter.com/kallmemeg/status/1396234498875043843

The table has useful data on how contact tracing is currently working. Deep dive 👇

#OpenData breeds trust in public health. It has been really heartening following @Pouriaaa and @statsgeekclare on Twitter running the awesome coronavirus.data.gov.uk dashboard in real-time. If you're not following (where have you been?!) this dashboard started simple, and has just continuously grown in quality and depth, buying in trust from both the public, and from the public health bodies who are institutionally nervous about #OpenData.

Now peer-reviewed in Nature, “The Epidemiological impact of the NHS COVID-19 App”. Here’s a quick rundown of results & what they mean. We estimated that the app prevented several hundred thousand cases from arising. The app works. nature.com/articles/s4158… 1/n We evaluated the app during the three months after its launch in England & Wales, Oct through December 2020. During this time, the app was actively used by 16.5 million people, 28% of the total population (map a users, map b, cases). 2/n

Our paper on evaluating the first three months of the NHS COVID-19 app is out now as a pre-print. A 🧵 1/n github.com/BDI-pathogens/… @markbriers @cholmesuk and I have written a blog about the research here

https://twitter.com/markbriers/status/1359061685613584385

As primary schools and some secondary schools in England and re-open tomorrow, the situation is unprecedented. The rate of confirmed infection in children is at its highest level yet. The situation is very different from last time there was a debate about school openings 1/n I think schools should close until case numbers are lower and it has been demonstrated that current restrictions can send the emerging new virus variant into decline. 2/n

New preprint: "PopART-IBM, a highly efficient stochastic individual-based simulation model of generalised HIV epidemics developed in the context of the HPTN 071 (PopART) trial" with Mike Pickles, @dr_anne_cori @p_robot and friends. 1/n medrxiv.org/content/10.110… A few years we found we needed an agent based model to simulate interventions against the HIV pandemic in southern Africa, and ended up developing a new one. We found that with heterogeneities and detailed interventions, ABMs were more parsimonious than compartmental models. 2/n

“England 'risks Covid-19 surge' without test-and-trace safety net” I agree, and am concerned about rapid easing of lockdown. 1/n. theguardian.com/world/2020/may… The ONS reports around 8,000 new infections per day, and that has not been declining quickly. 2/n ons.gov.uk/peoplepopulati…

Digital contact tracing may contribute to epidemic suppression of COVID. What are the trade-offs in choosing centralised or decentralised systems? . 1/n

github.com/BDI-pathogens/… There are three broad aims to be optimised: prevention of infection and disease, minimisation of disruptive requests to isolate, and maximisation of privacy. 2/n

@yhgrad @nicolamlow @nataliexdean @EHaroz @DFisman @marcelsalathe @eggersnsf @jackiecassell @profhelenward Important point. It's not either/or, and in context the money is not the issue. Digital contact tracing solves the problem of speed and recall bias, which is critical when faced with pre-symptomatic transmission and transmission from mild infections. @yhgrad @nicolamlow @nataliexdean @EHaroz @DFisman @marcelsalathe @eggersnsf @jackiecassell @profhelenward But to work, digital contact tracing needs support to reinforce messages, to provide information and reassurance, and crucially, to reach communities where uptake will be poor. We need to invest in multiple strategies, and build up evidence of what works and how to link together

“Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing” science.sciencemag.org/content/early/… 1/ Isolation, contact tracing, and quarantine are proven methods of infection control, but for COVID-19 conventional tracing is too slow. 50% of transmissions happen before symptoms, so the epidemic is always a step ahead. 2/

"Sustainable containment of COVID-19 using smartphones in China: Scientific and ethical underpinnings for implementation of similar approaches in other settings"

github.com/BDI-pathogens/… This is work with clinical-scientist @OxfordViromics and ethicist @michaelethox . We'll be following up with the analytics piece soon.

Discussions emphasising 'COVID19 is more serious than flu' will probably become moot in the coming days and weeks, and for many people already have, but in case you are engaged in them, I would consider trying to get accurate numbers for flu, and to make some general points. 1/n First off, flu mortality is sufficiently low that it is hard to measure, and requires a degree of modelling just to get at. That in itself tells you something. 2/n