1/ Q: When will we get to herd immunity?
A: When we get a vaccine & lots of people have received it; or else, a very long time from now.
A: When we get a vaccine & lots of people have received it; or else, a very long time from now.
2/ Even though we have well over 30 million confirmed cases & nearly a million deaths from #COVID19 worldwide, we’re not even close to reaching herd immunity. In fact, we're not even close to the lowest estimates for herd immunity in the places that were absolutely slammed early.
3/ Most scientists think that we need around 60-70% of people to be immune to #COVID19 in order to reach herd immunity. Herd immunity happens when a virus is starved of new hosts because susceptible people are so rare in the population.
4/ We can get that herd immunity threshold a little bit lower if we’re really strategic about who is immune. For example, for pertussis (known as whooping cough), you may have noticed that recent public health campaigns focus on vaccinating grandparents.
5/ Vaccinating grandparents is important because immunity from the pertussis vaccine starts to wear off as we age. We’re protecting newborns by making sure the people around them are immune. This strategy is called cocooning.
6/ There are other strategic ways to get the effective herd immunity threshold to be a little lower, such as requiring nursing home employees to be vaccinated annually for influenza. But even with a strategic program, we probably can’t get the threshold a lot lower than 60%.
7/ We’ve been through the looking glass for 9 months, & so far about 6.9 million people in the U.S. have confirmed infections. That’s about equal to the total population of the state of Arizona.
8/ Now let's do some imagining. Let's assume that having been previously infected actually does make us immune for life (which is still an open question). Let's also assume that we've under-identified cases--in fact we've only identified 1 in every 5 cases.
9/ That means we only have another 136 million cases to go until we reach herd immunity! 136 million people is roughly the combined population of the 10 biggest cities in the U.S. PLUS the entire population of FL., OH., GA, NC., MI., NJ., VA., WA., AZ., & TN. Combined.
10/ We would also expect between 500,000 & 2 million deaths, depending on how good we are at protecting our most vulnerable from infection. For comparison, the number of deaths would be something like the total population of New Hampshire.
11/ Now, let’s say that we’re all willing to accept the *completely insane* number of deaths involved in getting to herd immunity through natural infection. (Which, for the record, we are not. That is *not* a good public health strategy.)
12/ At the current rate, we’ll reach herd immunity in… 14 years & 5 months!
When & if an effective vaccine becomes available, we’ll still need to vaccinate millions & millions of people. But when we get vaccinated, we become immune *without getting sick*.
When & if an effective vaccine becomes available, we’ll still need to vaccinate millions & millions of people. But when we get vaccinated, we become immune *without getting sick*.
13/ Because of this cruel math & other reasons, the only reasonable way to achieve herd immunity is through a vaccine that is effective & widely adopted.
mayocl.in/2Ezpx1q
53eig.ht/3mNygyd
go.nature.com/3j2gO6U
#Infection #Spread #Uncertainty #Misinformation
mayocl.in/2Ezpx1q
53eig.ht/3mNygyd
go.nature.com/3j2gO6U
#Infection #Spread #Uncertainty #Misinformation
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