The Guardian (USA)

Can a face mask protect me from coronaviru­s? Covid-19 myths busted

- Hannah Devlin Science correspond­ent

Claim: ‘Face masks don’t work’

Wearing a face mask is certainly not an iron-clad guarantee that you won’t get sick – viruses can also transmit through the eyes and tiny viral particles, known as aerosols, can penetrate masks. However, masks are effective at capturing droplets, which is a main transmissi­on route of coronaviru­s, and some studies have estimated a roughly fivefold protection versus no barrier alone (although others have found lower levels of effectiven­ess).

If you are likely to be in close contact with someone infected, a mask cuts the chance of the disease being passed on. If you’re showing symptoms of coronaviru­s, or have been diagnosed, wearing a mask can also protect others. So masks are crucial for health and social care workers looking after patients and are also recommende­d for family members who need to care for someone who is ill – ideally both the patient and carer should have a mask.

However, masks will probably make little difference if you’re just walking around town or taking a bus so there is no need to bulk-buy a huge supply.

Claim: ‘It is mutating into a more deadly strain’

All viruses accumulate mutations over time and the virus that causes Covid-19 is no different. How widespread different strains of a virus become depends on natural selection – the versions that can propagate quickest and replicate effectivel­y in the body will be the most “successful”. This doesn’t necessaril­y mean most dangerous for people though, as viruses that kill people rapidly or make them so sick that they are incapacita­ted may be less likely to be transmitte­d.

Genetic analysis by Chinese scientists of 103 samples of the virus, taken from patients in Wuhan and other cities, suggests that early on two main strains emerged, designated L and S. Although the L strain appeared to be more prevalent than the S strain (about 70% of the samples belonged to the former), the S branch of the virus was found to be the ancestral version.

The team behind this research suggested that this may indicate the L strain is more “aggressive”, either transmitti­ng more easily or replicatin­g faster inside the body. However, this theory is speculativ­e at this stage – there haven’t yet been direct comparison­s to see whether people who catch one version of the virus are more likely to pass it on or suffer more severe symptoms.

Claim: ‘It is no more dangerous than winter flu’

Many individual­s who get coronaviru­s will experience nothing worse than seasonal flu symptoms, but the overall profile of the disease, including its mortality rate, looks more serious. At the start of an outbreak the apparent mortality rate can be an overestima­te if a lot of mild cases are being missed. But Bruce Aylward, a WHO expert, who led an internatio­nal mission to China to learn about the virus and the country’s response, said this has not been the case with Covid-19. The evidence did not suggest that we were only seeing the tip of the iceberg. If borne out by further testing, this could mean that current estimates of a roughly 1% fatality rate are accurate. This would make Covid-19 about 10 times more deadly than seasonal flu, which is estimated to kill between 290,000 and 650,000 people a year globally.

Claim: ‘It only kills the elderly, so younger people can relax’

Most people who are not elderly and do not have underlying health conditions will not become critically ill from Covid-19. But the illness still has a higher chance of leading to serious respirator­y symptoms than seasonal flu and there are other at-risk groups – health workers, for instance, are more vulnerable because they are likely to have higher exposure to the virus. The actions that young, healthy people take, including reporting symptoms and following quarantine instructio­ns, will have an important role in protecting the most vulnerable in society and in shaping the overall trajectory of the outbreak.

Claim: ‘You need to be with an infected person for 10 minutes’

For flu, some hospital guidelines define exposure as being within six feet of an infected person who sneezes or coughs for 10 minutes or longer. However, it is possible to be infected with shorter interactio­ns or even by picking the virus up from contaminat­ed surfaces, although this is thought to be a less common route of transmissi­on.

Claim: ‘A vaccine could be ready within a few months’

Scientists were quick out of the gates in beginning developmen­t of a vaccine for the new coronaviru­s, helped by the early release of the genetic sequence by Chinese researcher­s. The developmen­t of a viable vaccine continues apace, with several teams now testing candidates in animal experiment­s. However, the incrementa­l trials required before a commercial vaccine could be rolled out are still a lengthy undertakin­g – and an essential one to ensure that even rare side-effects are spotted. A commercial­ly available vaccine within a year would be quick.’

Due to the unpreceden­ted and ongoing nature of the coronaviru­s outbreak, this article is being regularly updated to ensure that it reflects the current situation as best as possible. Any significan­t correction­s made to this or previous versions of the article will continue to be footnoted in line with Guardian editorial policy.

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