With Covid studies, the quality of the evidence matters | David Spiegelhalter and Anthony Masters

Putting many low-quality studies together cannot provide reliable answers about masks and ivermectin

In The Adventure of the Copper Beeches, Sherlock Holmes says: “Data! Data! Data! I can’t make bricks without clay.” Recent claims of massive benefits from wearing masks and using ivermectin against Covid-19 depended on mainly low-quality clay.

Meta-analysis is a technique for pooling the results from many studies, but it cannot make silk purses out of sows’ ears. A recent British Medical Journal review looked at six, fairly porcine, studies concerning mask-wearing and estimated an impressive 53% reduction in risk. But the single randomised controlled trial estimated the smallest effect: a reduction of about 18% (-23% to 46%) in Sars-CoV-2 infections. The “heaviest” studies, an analysis of US states and a survey of about 8,000 Chinese adults in early 2020, observed rather than experimented and its editorial highlights the risks of confounding variables influencing both wearing masks and infections and the impossibility of disentangling the effects of measures fluctuating simultaneously. Indeed, this review found an identical 53% reduction from handwashing.

Continue reading...

Coronavirus | The Guardian

Comments

Post a Comment

Popular posts from this blog

Vaccine hesitant New Yorkers consider leaving the city as mandates take effect

For some in the Bronx, the borough hit hardest by the coronavirus, mistrust may win out over jobs and even home Deysia Padilla’s family thought she was at work. Instead, she spent last Thursday afternoon unloading a mound of orange and pink baby socks in a sunny South Bronx laundromat – one-by one, in all their three-inch glory. She had 48 hours to consider an impossible choice: either get vaccinated or lose her job. Padilla is one of thousands of unvaccinated New Yorkers affected by Mayor Bill de Blasio’s ultimatum last week. Not only do city employees face the reality of losing their jobs, but without a shot, they’ll even forgo unemployment payments . Some unvaccinated Bronx natives would rather pursue a life outside New York City than be forced to take the vaccine. Continue reading... Coronavirus | The Guardian
Read more

Coronavirus live news: AstraZeneca reports vaccine shortfall to EU; Sydney hotel quarantine worker tests positive

US administers 100m vaccine doses; Jordan patients die after hospital oxygen shortfall; Italy partial lockdown starts on Monday Australian PM and chief medical officer get second dose of vaccine Jordan health minister steps down after hospital oxygen failure deaths Lockdown ending could trigger anxiety for many, say UK charities Coronavirus – latest updates See all our coronavirus coverage 1.35am GMT Hong Kong is facing its fifth wave of infection, with a growing cluster centred around a high-end gym logging 99 cases so far . The gym is popular with the city’s central business district workers, local media reported, and several major banks and law firms are among dozens of businesses given compulsory testing orders. Authorities have also locked down four residential buildings in the Mid-levels, in another ambush-style operation to ensures all residents are tested overnight before being allowed to move freely again. 1.20am GMT Staying in Australia for a moment, there’s som...
Read more

One in six New York City workers remain unvaccinated after Friday deadline

Last-minute rush of jabs boost vaccination rate to 83% Fox News host gets death threats for vaccinations plea One in six New York City municipal workers remained unvaccinated after a Friday deadline to show proof of at least one dose of the Covid-19 vaccine, the city said. Despite opposition the city’s vaccine mandate fuelled by rightwing politicians and media and leading to a protest at City Hall this week, a last-minute rush of jabs boosted the vaccination rate to 83% among police officers, firefighters, garbage collectors and other city workers covered by the mandate as of 8pm on Friday. Continue reading... Coronavirus | The Guardian
Read more