WHO continues to confuse over wearing masks

London — It's an issue that's been argued about for months, both by experts and by people strolling through parks all over the world: Can people who don't feel sick spread the coronavirus, and if so should we all be wearing masks to stop it?

Even the World Health Organization can't seem to get it straight. On Tuesday the U.N. health agency scrambled to explain seemingly contradictory comments it has made in recent days about the two related issues.

The confusion and mixed messages only makes controlling the pandemic that much more difficult, experts say.

“If you are giving them confusing messages or they're not convinced about why they should do something, like wear masks, they will just ignore you,” said Ivo Vlaev, a professor of behavioral sciences at the University of Warwick.

The communications debacle highlighted WHO's change to its longstanding mask advice — a revision that was made months after many other organizations and countries already recommended people don masks.

On Friday, WHO changed its mask advice, recommending that people wear fabric masks if they could not maintain social distancing, if they were over age 60 or had underlying medical conditions. Part of the reasoning, WHO officials said, was to account for the possibility that transmission could occur from people who had the disease but weren't yet symptomatic.

But when Maria Van Kerkhove, WHO's technical lead on COVID-19 was asked about the frequency of this kind of transmission this week, she said “It still appears to be rare that asymptomatic individuals actually transmit onward.” On Tuesday, Van Kerkhove said she was referring to a few studies, not the complete picture.

Still, many other scientists were stunned by the description of asymptomatic spread as “rare,” saying plenty of evidence exists that people can spread the disease before suffering symptoms.

“I was surprised by the conviction of that statement because there have clearly been people who have transmitted the infection before they go on to develop symptoms,” said Keith Neal, an infectious diseases expert at the University of Nottingham who has advised the U.K. government on outbreak control.

The details on how well the coronavirus spreads in different circumstances is not well understood, and is still being studied.