The Sharing Scientist Profile picture
Bringing you the most interesting & important science news that you need, summarised & sourced directly to your feed. Current focus: COVID investigations
We're all in this together (separately) #staysafe Profile picture 2 added to My Authors
15 Jun
A Cost-Benefit Analysis of the COVID-19 Asymptomatic Mass Testing Strategy in the North Metropolitan Area of Barcelona


Summary 🧵…
"The results show that the interventions with the highest return are those that maximize the percentage of positives detected."

"Efficient management of resources for the policy of mass screening in asymptomatic populations can generate high social returns."
"The positivity rate critically determines its desirability."

"Likewise, precocity in the detection of cases will cut more transmissions in the chain of contagion and increase the economic return of these interventions."
Read 13 tweets
14 Jun
Worth stating that, while there is (significant) potential for a significant autumn/winter CoV-2 wave of *cases*, a wave in a population in which 95%+ of adults are double-dosed is different to a wave in which they are not, even w/ waning immunity & novel VOCs

- Caveats below 👇
- Does not apply if there is a *true* vaccine escape variant, the potential of which is unknown, but seems relatively small 🤞
- Immunity to infection/infectiousness definitely does/will wane, altho by how much & exact time-scales is currently unknown & will differ in different demographics, & v unknown what this means (quantitatively) for severe disease (although less likely to be impacted so much).
Read 7 tweets
13 Jun
This was intended as a somewhat light-hearted tweet, but have realised it actually points to a much wider issue.

Media, politicians, some scientists are banging the 'third wave' drum. But much of the country is actually going through its 4th wave...
Maybe epidemic waves only count if they happen in the South East? 🤷‍♂️
And again points to the issue that when Blackburn & other parts of NW were going through surge of cases of Delta, many called for the reimpositon of restrictions here.
Read 4 tweets
9 Jun
Really beginning to question the scientific integrity of those who state with certainty that the restrictive interventions they favour 'work' for net-PH benefit, while any attempts to actually study &/or optimise implementation of more focussed PH interventions are unethical.
Perhaps this Wikipedia page will help?….
Would also remind people that we have all been living through one local, national, and global 'experiment' over the past year, with a package of blunt interventions of completely unknown (cost)-effectiveness and many collateral (known and unknown) harms.
Read 5 tweets
9 Jun
Came across the UEFA Guidance on Euro 2020 Testing in Stadiums.

Is it up to scratch e.g., likely to be effective?

Short 🧵on the effectiveness of UEFA Euro 2020 event testing protocols..…
For event testing to be most effective, you want to ensure swabbing quality & that people are testing as close as possible to the event (ideally within 12 hours but 24 hours is acceptable).

NB - Ensuring same-day event testing at a test-site is logistically challenging.
The current guidance states a self-administered swab for a rapid antigen test must be taken within 48 hours of stadium gates opening, and 'proof' of result given via text or email.

These tests can be self-administered (at home), or taken at an asymptomatic testing site.
Read 12 tweets
9 Jun
Higher prevalence amongst children actually makes the argument to do these pilots stronger.

Swathes of lost education nationwide, and children/whole classrooms having to repeatedly isolate & not receiving normal school-based care/fun generally, carries significant harms.
If there is a way to reduce these harms without increasing transmission through daily testing of contacts, which modelling/logic suggests can work, then it is worth evaluating through (high-quality) pilots.
There are no easy answers here, and everything is trade-offs. But if every pilot and attempt to understand ways to improve the situation & reduce total harms now we are in the vaccination era results in outcries of unethical study, we are unlikely to get very far.
Read 9 tweets
8 Jun
All of the below can be true

1) LFDs can be a very useful PH tool
2) People in the testing industry make a lot of money
3) The tests aren't being used in a particularly (cost) effective/efficient programme
4) DHSC are not evaluating them anywhere near well enough..
5) Misinformation around (LFD) testing, promoted by prominent academics in the media and certain newspapers, has, and continues to, erode trust in testing and public health, impacting on uptake and therefore impeding pandemic responses.
6) Seemingly subtle differences in transmission control can have significant net health/societal benefit at certain key points of the epidemic (e.g., when R close to 1, and/or in a tight race between mass vaccination & reopening with VOCs circulating).
Read 5 tweets
7 Jun
Fellow researchers - Which 3 papers are most relevant/important to your current work?
Mine are

1) Single-molecule imaging of microRNA-mediated gene silencing in cells…
2) PANDORA-seq expands the repertoire of regulatory small RNAs by overcoming RNA modifications…

3) Phase Transitions in the Assembly and Function of Human miRISC
Read 4 tweets
7 Jun
The problem with models forecasting late into 2021/early 2022, with implications for challenging winter waves, etc, is that there is still evolutionary space for the virus to become more transmissible &/or acquire further (partial) vaccine resistance.
Therefore, these forecasts will soon become somewhat redundant imho.

The most optimal strategy is still to keep prevalence low with focussed and effective evidence-based interventions, balancing harms & not losing focus, & take each day, week, month as it comes...
Scenarios, not forecasting, obviously - sorry.

Read 5 tweets
5 Jun
The fine margins on this are just crazy. Note this is illustrative data, but (illustratively), R(t) dropping by 0.1 per day due to vaccination = no exit wave, while R(t) dropping by 0.05 per day = large exit wave.

I have written about the fine margins of R(t) and epidemic outcomes numerous times throughout the pandemic.

Many seem to forget, or haven't acknowledged, when evaluating the effectiveness of an intervention, such as symptomatic or asymptomatic, testing, it is not static...
A dynamic epidemic means sometimes an intervention, such as testing, can have a small effect on transmission, therefore seeming ineffective.

However, at certain phases in the epidemic, a reduction in R of eg. 0.005 can completely change the course of the pandemic...
Read 6 tweets
3 Jun
Estimating epidemiologic dynamics from cross-sectional viral load distributions

Pre-print was very useful (to me anyway), so good to see an updated version properly published in @ScienceMagazine today

@mlipsitch @michaelmina_lab…
Estimating an epidemic’s trajectory is crucial for developing public health responses to infectious diseases.

Authors show that Ct values (from even limited numbers of random samples) can provide improved estimates of an epidemic’s trajectory. 📈 📉 ✅
Valuable in a variety of settings, and can offer alternative approaches for real-time estimates of epidemic trajectories for outbreak management and response.
Read 6 tweets
1 Jun
@chrischirp Quite - hence my gazillion tweets over last 8 months on implementation, equitable and focussed testing, testing fatigue, maximising benefit from finite resources, symptoms, credible incentives, and support to isolate.
@chrischirp Despite the 24/7 COVID news cycle, constant lockdown vs no lockdown debates, & in-depth reviews of variants & attempts to explain molecular biology to the British public, there has been a distinct lack of comms on the practical steps which members of the public can take... ->
@chrischirp -> to reduce their risk of catching & spreading COVID before being fully vaccinated.

Encouraging self-symptom screening (WHO definition) before leaving the house, meeting up outdoors/opening windows, rapid testing 2x week (or before you meet people).

Read 4 tweets
24 May
The acceptability of testing contacts of confirmed COVID-19 cases using serial, self-administered lateral flow devices as an alternative to self-isolation.…
Very valuable findings (which went under the radar, unfortunately), providing evidence to support the larger pilot scheme of daily contact testing to replace quarantine.

Quarantine is not easy - it can have sig harms on individuals, especially if they are (financially, physically, or mentally) vulnerable.…
Read 9 tweets
23 May
Mask requirements for teachers & staff members & improved ventilation are important strategies in addition to vaccination of teachers & staff members that elementary schools could implement as part of a multicomponent approach to provide safer, in-person learning environments. ImageImage
Of interest in this analysis is that this real world analysis by @CDCgov found relative risk of COVID transmission when students required to wear masks vs when optional was 0.79 (not a huge reduction) and confidence intervals crossed 1 (0.50-1.08). Image
Read 6 tweets
22 May
Interesting that DC continues to think mass testing was the obvious solution to prevent 2nd/3rd waves, & delayed procurement/roll-out enabled waves.

But still no mention of support to isolate in this long thread..

Overly technocratic narrative when holistic PH framing required.
The testing *programme* in its entirety, not just having tests themselves, are what really matter.
L'pool results suggest mass testing in this format (w/o support to isolate which reduced uptake in communities where needed most) was unable to prevent a sig wave while society open
Altho v complex data-set to disentangle, & confounded a lot by Lpool being in T2 rather than T3 (due to earlier gains from mass testing) resulting in much seeding of cases (& B117) to the region, does suggest such mass testing unable to prevent sig wave while society more open.
Read 9 tweets
22 May
How do the UK public interpret COVID-19 test results?

Comparing the impact of official information about results and reliability used in the UK, USA and New Zealand: a randomised controlled trial…
"The public’s default assessment of the face value of both the positive and negative test results (control group) indicate an awareness that test results are not perfectly accurate."
"Compared with other messaging tested, participants shown the UK’s 2020 wording about the interpretation of the test results appeared to interpret the results as more definitive than is warranted."
Read 9 tweets
21 May
'We estimated that the probability that the PCR test detected infection peaked at 77% (54–88%) 4 days after infection, decreasing to 50% (38–65%) by 10 days after infection.'…
'Our results suggest a substantially higher probability of detecting infections 1–3 days after infection than previously published estimates.'

A certain someone might find this paper useful to read...
OTOH, who cares about any of that nonsense when you can tweet out baseless accusations and ill-informed nonsense on things you, quite frankly, don't have a clue about and go viral...!
Read 4 tweets
20 May
Genuinely can't tell whether this language is a coordinated effort by @UKLabour to amplify the nationalist 'leaky border' anti-immigration/anti-foreigner hype in an attempt to win back votes, or whether this is just where so-called 'progressive' politics finds itself in 2021.
Patrolling race and the UK's medical borders

"As the COVID-19 pandemic continues, we must be attentive to the social implications of linking national security with the exclusion of “foreign” bodies."… Image
'Leaky borders,' 'flooding,' 'migration flows,' 'plague pits' etc etc etc.

We've been here before...

Closed due to ‘flooding’? UK media representations of refugees and migrants in 2015–2016 – creating a crisis of borders…
Read 8 tweets
12 May
In my view, the best strategy option the UK has, until vaccination coverage is greater/complete, is to keep national and regional R ≤ 1.

A thread 🧵 on why, and how we can do that without extending/re-imposing harsher restrictions, below. 👇
While UK's vaccination has been transformational, there is still a large proportion of our population unvaccinated.

This means herd immunity threshold has not been met, & there is sig potential for surges, esp in some regions.

We are already seeing R & prevalence rise in certain regions, esp in the NW & elsewhere. Where there is greater socio-economic deprivation, less people WFH, inequities in vaccine accessibility & uptake, & waning immunity, the potential of R(t) is greater.

Read 24 tweets
10 May
Aerosol generating procedures: are they of relevance for transmission of SARS-CoV-2?

Full @LancetRespirMed commentary worth a read if you're interested.

Inferences from data presented here support importance of coughing in transmission of SARS-CoV-2.

"It is now generally accepted that SARS-CoV-2 can be spread by aerosols as well as larger droplets from the upper respiratory tract, although the relative importance of aerosol transmission remains incompletely answered."
"This view of aerosol generation subsequently led to a dichotomisation that categorised all medical activities into either AGPs, where potentially infectious aerosols are generated, vs everything else, where risk of potentially infectious aerosol is presumed negligible."

Read 16 tweets
9 May
The Confusing and At-Times Counterproductive 1980s Response to the AIDS Epidemic

A new exhibit looks at the posters sent out by non-profits and the government in response to the spread of AIDS

Through exploring the exhibit, users get a sense of the different approaches public organizations took to spread information about AIDS. "It's a fundamental question of public health," says Brier.

"Do you spread information by scaring people, do you do it by trying to tap into pleasure or do you do it by recognizing that people’s behavior isn’t just about their individual will but a whole different set of circumstances?"

An interesting perspective.

Read 6 tweets