Posted on by Dr. Francis Collins
There’s been much interest in using digital technology to help contain the spread of COVID-19 in our communities. The idea is to make available opt-in smart phone apps that create a log of other apps operating on the phones of nearby participants. If a participant tests positive for COVID-19 and enters the result, the app will then send automatic alerts to those phones—and participants—who recently came into close proximity with them.
In theory, digital tracing would be much faster and more efficient than the challenging detective work involved in traditional contract tracing. But many have wondered how well such an opt-in system would work in practice. A recent paper, published in the journal Nature, shows that a COVID-19 digital tracing app worked quite well in the United Kingdom .
The research comes from Christophe Fraser, Oxford University, and his colleagues in the U.K. The team studied the NHS COVID-19 app, the National Health Service’s digital tracing smart phone app for England and Wales. Launched in September 2020, the app has been downloaded onto 21 million devices and used regularly by about half of eligible smart phone users, ages 16 and older. That’s 16.5 million of 33.7 million people, or more than a quarter of the total population of England and Wales.
From the end of September through December 2020, the app sent about 1.7 million exposure notifications. That’s 4.4 on average for every person with COVID-19 who opted-in to the digital tracing app.
The researchers estimate that around 6 percent of app users who received notifications of close contact with a positive case went on to test positive themselves. That’s similar to what’s been observed in traditional contact tracing.
Next, they used two different approaches to construct mathematical and statistical models to determine how likely it was that a notified contact, if infected, would quarantine in a timely manner. Though the two approaches arrived at somewhat different answers, their combined outputs suggest that the app may have stopped anywhere from 200,000 to 900,000 infections in just three months. This means that roughly one case was averted for each COVID-19 case that consented to having their contacts notified through the app.
Of course, these apps are only as good as the total number of people who download and use them faithfully. They estimate that for every 1 percent increase in app users, the number of COVID-19 cases could be reduced by another 1 or 2 percent. While those numbers might sound small, they can be quite significant when one considers the devastating impact that COVID-19 continues to have on the lives and livelihoods of people all around the world.
 The epidemiological impact of the NHS COVID-19 App. Wymant C, Ferretti L, Tsallis D, Charalambides M, Abeler-Dörner L, Bonsall D, Hinch R, Kendall M, Milsom L, Ayres M, Holmes C, Briers M, Fraser C. Nature. 2021 May 12.
COVID-19 Research (NIH)
Christophe Fraser (Oxford University, UK)
Posted on by Dr. Francis Collins
Since the genome sequence of SARS-CoV-2, the virus responsible for COVID-19, was first reported in January 2020, thousands of variants have been reported. In the vast majority of cases, these variants, which arise from random genomic changes as SARS-CoV-2 makes copies of itself in an infected person, haven’t raised any alarm among public health officials. But that’s now changed with the emergence of at least three variants carrying mutations that potentially make them even more dangerous.
At the top of this short list is a variant known as B.1.1.7, first detected in the United Kingdom in September 2020. This variant is considerably more contagious than the original virus. It has spread rapidly around the globe and likely accounts already for at least one-third of all cases in the United States . Now comes more troubling news: emerging evidence indicates that infection with this B.1.1.7 variant also comes with an increased risk of severe illness and death .
The findings, reported in Nature, come from Nicholas Davies, Karla Diaz-Ordaz, and Ruth Keogh, London School of Hygiene and Tropical Medicine. The London team earlier showed that this new variant is 43 to 90 percent more transmissible than pre-existing variants that had been circulating in England . But in the latest paper, the researchers followed up on conflicting reports about the virulence of B.1.1.7.
They did so with a large British dataset linking more than 2.2 million positive SARS-CoV-2 tests to 17,452 COVID-19 deaths from September 1, 2020, to February 14, 2021. In about half of the cases (accounting for nearly 5,000 deaths), it was possible to discern whether or not the infection had been caused by the B.1.1.7 variant.
Based on this evidence, the researchers calculated the risk of death associated with B.1.1.7 infection. Their estimates suggest that B.1.1.7 infection was associated with 55 percent greater mortality compared to other SARS-CoV-2 variants over this time period.
For a 55- to 69-year-old male, this translates to a 0.9-percent absolute, or personal, risk of death, up from 0.6 percent for the older variants. That means nine in every 1,000 people in this age group who test positive with the B.1.1.7 variant would be expected to die from COVID-19 a month later. For those infected with the original virus, that number would be six.
These findings are in keeping with those of another recent study reported in the British Medical Journal . In that case, researchers at the University of Exeter and the University of Bristol found that the B.1.1.7 variant was associated with a 64 percent greater chance of dying compared to earlier variants. That’s based on an analysis of data from more than 100,000 COVID-19 patients in the U.K. from October 1, 2020, to January 28, 2021.
That this variant comes with increased disease severity and mortality is particularly troubling news, given the highly contagious nature of B.1.1.7. In fact, Davies’ team has concluded that the emergence of new SARS-CoV-2 variants now threaten to slow or even cancel out improvements in COVID-19 treatment that have been made over the last year. These variants include not only B1.1.7, but also B.1.351 originating in South Africa and P.1 from Brazil.
The findings are yet another reminder that, while we’re making truly remarkable progress in the fight against COVID-19 with increasing availability of safe and effective vaccines (more than 45 million Americans are now fully immunized), now is not the time to get complacent. This devastating pandemic isn’t over yet.
The best way to continue the fight against all SARS-CoV-2 variants is for each one of us to do absolutely everything we can to stop their spread. This means that taking the opportunity to get vaccinated as soon as it is offered to you, and continuing to practice those public health measures we summarize as the three Ws: Wear a mask, Watch your distance, Wash your hands often.
 US COVID-19 Cases Caused by Variants. Centers for Disease Control and Prevention.
 Increased mortality in community-tested cases of SARS-CoV-2 lineage B.1.1.7. Davies NG, Jarvis CI; CMMID COVID-19 Working Group, Edmunds WJ, Jewell NP, Diaz-Ordaz K, Keogh RH. Nature. 2021 Mar 15.
 Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England. Davies NG, Abbott S, Barnard RC, Jarvis CI, Kucharski AJ, Munday JD, Pearson CAB, Russell TW, Tully DC, Washburne AD, Wenseleers T, Gimma A, Waites W, Wong KLM, van Zandvoort K, Silverman JD; CMMID COVID-19 Working Group; COVID-19 Genomics UK (COG-UK) Consortium, Diaz-Ordaz K, Keogh R, Eggo RM, Funk S, Jit M, Atkins KE, Edmunds WJ.
Science. 2021 Mar 3:eabg3055.
 Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study. Challen R, Brooks-Pollock E, Read JM, Dyson L, Tsaneva-Atanasova K, Danon L. BMJ. 2021 Mar 9;372:n579.
COVID-19 Research (NIH)
Nicholas Davies (London School of Hygiene and Tropical Medicine, U.K.)
Ruth Keogh (London School of Hygiene and Tropical Medicine, U.K.)