A prominent scientist has taken health minister Matt Hancock to task for casting doubt on the effectiveness of face masks to fight the spread of coronavirus (Covid-19).

Hancock told ITV’s Peston programme on 15 April it was important the government made the right decisions on the supply and use of face masks amid continuing high demand for them, saying “if they don’t help, then it doesn’t improve the national effort to tackle this virus”.

But Hancock’s comments were disputed by University of San Francisco data scientist Jeremy Howard, who recently led a review panel with 18 other experts from around the globe on the effectiveness of masks in warding off the virus.

Howard said the evidence “does not at all show what he (Hancock) claimed” on whether masks were vital.

“It actually looks a lot like this could be one of our most important tools,” Howard told the programme.

Howard cited World Health Organisation assistant director-general David Heymann’s comment that masks were equally or more effective in combating the spread of Covid-19 than social distancing, and said the situation in Taiwan provided further proof.

“Regardless of how you look at it, it looks like there’s an extra 1,500 deaths a week (in the UK) due to this disease. The entire country of Taiwan has five deaths. Now here’s an example of a great country that is distributing masks to everybody,” Howard said.

Our team’s review of the literature found substantial evidence in favor of widespread mask use to reduce community transmission, based on droplet dynamics, mask material analysis, efficacy studies, and behavioral studies. Here’s our paper: https://t.co/DyVtds2sx8 — Jeremy #Masks4All Howard (@jeremyphoward) April 13, 2020

Earlier this week, Howard tweeted: “Most scientific evidence points in the same direction: keep your droplets to yourself – wear a mask.”

“Our team’s review of the literature found substantial evidence in favour of widespread mask use to reduce community transmission, based on droplet dynamics, mask material analysis, efficacy studies, and behavioural studies,” he tweeted.

“The key insight is that most discussions assume that the purpose of the mask is to protect the wearer, since this is what all doctors learn about in medical school. But actually masks work far better at blocking the infection at the source. This is called ‘source control’.”