Can you get Covid twice and can I wear a scarf as a face cover?

Q Can you catch the virus twice?

A Yes, but it’s unlikely. According to the World Health Organisation (WHO), there have been roughly 25 cases of Covid-19 patients recovering from the virus, then testing positive some weeks later. But that’s out of a total of 38 million cases worldwide.

The issue hit the headlines again last week when a 25-year-old, otherwise healthy man from the US was reported to have caught the virus twice in little over six weeks, with the second infection much more severe than the first.

Previously, scientists had assumed that the fighter cells and proteins released by the immune system in response to the first infection would ward off a second bout.

But there may be reasons behind the second infection. For instance, the patient may have encountered a relatively small dose of the virus first time round – enough to trigger symptoms but only a weak immune response.

A second possible explanation is something called antibody-dependent enhancement, a very rare reaction where instead of attacking and destroying the virus, antibodies released by the immune system help it.

Until more is known about the risks of reinfection, even those who have recovered from Covid-19 are advised to follow guidance on social distancing, use of face masks and handwashing.

Does wearing a scarf over my face offer the same protection as a face mask?

Q A It will offer some, but not as much as a proper mask. The WHO says face coverings should have three layers: the first absorbs moisture from your mouth, a middle one traps droplets and an external layer repels droplets in the air.

‘A scarf will offer much less protection to those around you than a decent face mask if you are carrying the coronavirus,’ says Dr Simon Clarke, associate professor of cellular microbiology at Reading University. ‘It’s unlikely to fit tightly and more likely to be made of loosely woven fabric with thicker fibres. This means there are more gaps that droplets could pass easily through.’

But, as Dr Julian Tang at Leicester University, points out, scarves are better than nothing.