(upbeat music) - Ladies and gentlemen,
Dorthy and her birds.
- [Narrator] Remember when things were normal?
When you could do normal stuff without a mask,
without social distancing, without worrying about COVID-19?
So when can we get back to normal?
For that, we'll have to achieve herd immunity.
Herd in this case can apply to any multitude of animals.
We'll just go with birds.
The basic idea is pretty simple.
In order to spread viruses, to infect people.
If enough people are immune, they create a sort of barrier
that keeps the virus from finding new people to infect.
And in the process protects people
who aren't immune.
That's herd immunity.
The concept
(cows mooing) has been around
for more than a century.
In fact, one of the earliest mentions came in 1921
from Oregon State University
in reference to a nasty bacterial disease in cows.
- (indistinct) Got a blackleg vaccine
to keep you (indistinct).
- [Narrator] Figuring out how many cows, humans,
or any other animal need to be immune
to protect the whole herd depends on how infectious
a disease is.
This is the R value.
It refers to how many people each sick person
is expected to pass the virus onto.
A disease like Ebola has an R value of around two.
If nobody did anything to slow it down,
a sick person would infect two others.
Smallpox has an R-value of closer to four
and this seemingly small change makes a huge difference
in how quickly each disease spreads.
But everything turns around when we get enough immunity
to drop the R value below one.
At that point, the virus can't spread as easily
and it eventually fizzles out.
The more infectious the disease,
the more immune people we need
to drop that R-value value down below one.
With an R value of two, you only have to cross 50% immunity.
At R equals four, that herd immunity goal rises to 75%.
For COVID-19 estimates are we'll need at least 70% immunity
to get us back to normal.
For most of human history, the only way to get herd immunity
was to let the disease run its course.
Basically let a lot of people die.
Vaccines change that calculus in a big way,
providing a much safer way for people to become immune.
With vaccines, herd immunity is not only possible,
it's within reach.
Take Oregon for example.
With the population topping 4 million,
the state would need to have a little less
than 3 million people immune to COVID-19
to reach herd immunity.
At the end of January, 2021,
there was about 140,000 confirmed coronavirus infections.
That sets our vaccine goal to around 2.8 million people
to hit that 70%.
At the state's average, late January vaccine rate
of 16,000 doses per day,
we'll get there by December, 2021.
Pretty straightforward?
Nope. It's never that easy.
First off, the vaccine hasn't been approved
for kids and teens under 16.
That's about 17% of Oregon's population
who can't get vaccinated.
That means 90% of the remaining adults will need vaccines
to hit herd immunity.
And then there's the coronavirus variants
that have popped up, which can be more infectious.
And consider COVID-19 vaccines top out at 95% effective,
meaning more people will need it.
And then the real wild card,
we don't know how long the vaccines will last.
Booster shots are being developed,
but it's possible that some people
will start to lose vaccine immunity
before the herd is protected.
So normal keeps getting pushed back, which is daunting
and more than a little exhausting.
But it's not all bad.
It's highly likely that far more people
have had COVID-19 than we know.
So we have an added buffer of natural immunity built in
and all the work we've been doing,
wearing masks and staying socially distanced,
it's already significantly slowed
how quickly coronavirus spreads.
If we keep that up and keep the vaccines coming,
COVID cases and deaths are going to plummet.
When that happens, social restrictions will start to relax
and normal may become the norm again, sooner than we think.
- (indistinct) Dorthy and her fabulous birds of the world.