A post on Facebook claims that while there’s only a 0.26% chance of catching Covid-19, there’s a 0.42% chance of an asteroid hitting Earth on 2 November. It continues: “I don’t know about you lot but I’m trading my mask in for a[...]helmet.”
In all likelihood, it’s a better idea to keep a hold of your mask. Your chance of catching Covid-19 is likely much higher than that (although this will vary depending on where you live and what you do), while the asteroid would burn up in the Earth’s atmosphere.
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The Covid-19 infection rate
The 0.26% figure in the post actually refers to the chance of dying from Covid-19 if you catch it, not the chance of catching it in the first place.
This figure was estimated based on figures published by the US Centers for Disease Control and Prevention in May.
Back then, the CDC estimated that 0.4% of people who developed symptoms of Covid-19 would die of it, and that 35% of cases were asymptomatic (and so 65% were symptomatic).
By multiplying 65% by 0.4% you get a 0.26% fatality rate, though this calculation wasn’t done by the CDC itself.
Since then the CDC has published estimates for the “infection fatality ratio” (IFR) by age band. It’s still unclear exactly what the overall IFR is and this may change over time as, for example, medical advancements mean the survival rate increases.
Also the IFR will vary between countries and by age, and therefore doesn’t really measure an individual’s own risk of dying from the disease.
As for the risk of catching Covid-19 in the first place, which the post refers to, this again will vary highly depending on the country and situation of individuals so there isn’t one figure for it.
However, we can say how many people are thought to have Covid-19 at any one time. In England, during the period of just one week in October, the Office for National Statistics estimated that around 0.77% of the people were infected with Covid-19. Antibody studies suggest that around one in eight people in London had caught it by mid-July.
The chance of an asteroid hitting Earth
The post refers to an asteroid named 2018VP1 which NASA says has a 0.41% chance of entering Earth’s atmosphere.
However NASA says that if it did, it would disintegrate in the atmosphere before reaching Earth’s surface as it is small, only around 6.5 feet wide.
NASA also says: “About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface.
“Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.”