Thread by @drsimonwilliams

🚨Our MAJOR new @royalsociety report out TODAY

Evidence shows COVID measures together = EFFECTIVE

Key findings:

➡️Distancing/lockdowns=MOST EFFECTIVE measure

😷 FACEMASKS consistently found to be EFFECTIVE

➡️Strong evidence for contact tracing apps

royalsociety.org/topics-policy/…

2/n

✈️Comprehensive border control policies reduce, but dont eliminate, infections entering countries.

🪟 ventilation did reduce transmission in particular settings (but hard to quantify)

📣communication helped ensure high adherence, but trust & clarity = key barriers

3/n Fantastic to be part of such a collaborative effort with leading global experts including:

Sir Mark Walport (Chair) @wendybarclay11 @mugecevik @chris0dye @bencowling88 @melindacmills et al - full list of contributors here 👇

@wendybarclay11 @mugecevik @chris0dye @bencowling88 @melindacmills 4/ Lets take a deeper dive into findings:

📈 measures most effective when transmission was low ➡️ NEED TO use early in a pandemic & first sign of resurgence/wave

BUT-measures use can have adverse personal, educational, and economic consequences .. more research needed on these

5/ We examined THOUSANDS of studies using rigorous methods.

According to Chair, Sir Mark Walport:

“There is sufficient evidence to conclude that early, stringent implementation of packages of complementary NPIs was unequivocally effective in limiting SARS-CoV-2 infections."

6/Lets look at each review in turn.

1. MASKS:

N=35 studies in community settings (3 RCTs) & 40 in healthcare settings (1 RCT).

😷 MAJORITY of studies found that masks (87%) and mask mandates (89%) REDUCED infection compared to those that found no effect (12%).

7/ Caveat: most of the studies were observational rather than experimental (lots with critical risk of bias).

But, weight of evidence suggests that masks and mask mandates generally reduced transmission.

8/
2. SOCIAL DISTANCING AND LOCKDOWNS:

Overall, social distancing measures were associated with CONSIDERABLE reductions in COVID transmission.

Specifically:

🏫SCHOOLS: closures and other measures associated with reduced COVID-19 incidence within schools and the community

9/
🏥CARE HOMES:

cohorting of staff, & residents and restrictions on visitors=reduced COVID transmission and reduced outbreaks within care homes

[earlier the measures implemented the better in care homes!]

But: less clear evidence for effectiveness in other workplace

10/ Large evidence base for social distancing/lockdown effectiveness (the single most effective measure for reducing transmission) 👇

(BUT more experimental studies ideal)

11/

3. COMMUNICATIONS. This was our review, with @KimberlyDienes @jamiewardman @JemmaJJ_ and Prof Judith Petts.

Overall, communication was *good enough* to ensure high adherence (which was high during pandemic), BUT

Three main barriers to effective communication identified:

12/ We reviewed 11,500 studies (!) - with 13 meeting inclusion criteria.
A key inclusion criteria was was behaviour (masking, distancing etc) actually measured

In future we need more good studies that actually measure actual behaviour, not just intentions/willingness!

13/

4. ENVIRONMENTAL CONTROLS

MODE OF TRANSMISSION: did cleaning surfaces work (big focus esp. early in pandemic)

Review DID NOT find sufficient evidence to conclude whether enhanced cleaning practice was an effective measure in reducing transmission.

14/

VENTILATION:

Review found evidence that improved ventilation reduced the transmission of virus between humans in real world scenarios.

BUT: many studies low quality due to confounding factors. Also - didnt find evidence at population level (only in specific settings)

15/

Perspex Screens (remember those?)

A lack of evidence as to whether barrier devices were useful in reducing transmission of airborne COVID

Some suggested screens can even IMPEDE effectiveness of room ventilation by increasing stagnant air zones!

16/ Which countries did well (case studies).

first: NEW ZEALAND!

NZ experience shows how a comprehensive package of border controls can be HIGHLY EFFECTIVE at preventing the importation of COVID-19.

17/ full evidence reviews here:



thanks to @royalsociety & a fantastic team of scientists

In short:

Covid measures WERE EFFECTIVE including lockdowns, contact tracing & masks

Some can still be useful in future as needed in this or future outbreaksroyalsocietypublishing.org/doi/10.1098/rs…