have been detected in over 40 countries,

including the UK, South Africa, Nigeria and Brazil

where they first emerged.

- Now health officials say a new threat

is identified in South Africa.

- British officials imposed a new lockdown across England.

- Recent reports of a highly contagious coronavirus variant

in the United States.

- [Narrator] In the US, multiple states

have reported new variants

or versions of the virus with mutations

that could change how it spreads.

New research suggests

that some of these variants are highly transmissible

and at least one may reduce how well vaccines work.

With countries around the world

already facing escalating infections

and overwhelmed hospitals,

these mutations could make ending

the pandemic more difficult.

We'll explain.

Like other viruses, the coronavirus spreads

by infecting cells and then reproducing within them,

creating copies of itself that spread throughout the body.

As new versions are made, the virus' genetic code,

which holds the instructions

for building new virus particles is copied over

and over again.

But the code isn't always reproduced correctly.

Small genetic mistakes or mutations

can create new viral variants.

If the new version of the virus has mutations

that allow it to spread faster

than the current most common variant,

it could lead to a surge in new cases.

This is already happening in places

like the UK and South Africa

where some of the newest ones were first found.

Current data suggests that the UK variant

could be 50% to 70% more transmissible

but the research is still early.

To determine how transmissible

and dangerous a virus mutation might be,

scientists run a series of experiments in the lab.

The first step is genetic sequencing.

- Genetic sequencing gets to the blueprint

of what the viruses are.

We can use samples and data

from actual humans to figure out

what the genetics of the viruses are.

- [Narrator] To do this, scientists take a sample

of the mutated virus and sequence its genes.

Then computation programs

help scientists identify mutations.

- Once we know what they are

and now we can see that oh well,

this is an important population,

we can start manipulating the virus.

We can either start working with clinical islets

of that virus or we can actually make the strains.

So putting those individual mutations

into the backbone of viruses that we already have.

- [Narrator] After sequencing the virus,

scientists test the variant in a lab.

- What we do is we compare how well the virus replicates

in different types of cells.

And so there are two ways.

We will just do infections and kind of measure the level

of the virus over time in these cell types.

And the other thing that we'll do is a competition,

where we'll take 50% of the wild type,

the original strain and 50% of the mutant strain

and then compare how well they grow.

If there's an advantage, we'll see that

that advantage 24 hours or after 48 hours,

one of the two might out compete.

- [Narrator] During lab experiments,

researchers can also test whether human antibodies created

by infection or vaccines

are effective at fighting the new form of the virus.

After culture testing,

scientists typically move on to animal models

and then sometimes to humans.

Right now, the research is still early

but scientists are beginning to get a clearer picture

of what these variants look like.

From sequencing, they know the UK variant

has 17 key mutations.

- These variants that we're seeing,

these changes give a small advantage

in terms of the ability of the virus

to replicate or transmit.

- [Narrator] This has a lot to do with the spike protein,

which is critical to how the virus spreads.

A portion of the spike bonds to a receptor

on human cells like a key fitting into a lock.

This enables it to enter and infect.

Scientists found that the UK variant's spike proteins

have eight amino acid changes.

Previous research appears to show

that some of these changes may be increasing

the protein's ability

to cling onto and enter human cells.

This could be making it more transmissible,

which means a higher vaccination rate may be needed

to reach herd immunity.

Another big question is the virulence

or how harmful these new versions of the virus could be.

Scientists say that most likely the new variants

don't cause a more severe form of COVID-19.

Another question is whether the new versions

will show up on tests.

Early data appears to show that most COVID

and antibody testing will continue to work.

- We should still be able to tell if you have COVID.

What's less clear is if we can tell

if you have a specific variant or not.

- [Narrator] The most pressing issue

is whether vaccines will still be effective.

For the UK variant, it appears that they will.

However, for the variant originating in South Africa,

preliminary data is worrying some scientists.

Researchers say that any of the more transmissible variants

could eventually become dominant.

- We've seen variants take over

in terms of the D614G mutation

and it wouldn't surprise me if the South African

or the UK variant do a similar thing

where it becomes a dominant variant around the world

just because of a small fitness advantage

or small changes that make the virus more fit.

- [Narrator] To try to stem the spread,

certain countries like the UK

have already imposed strict lockdown measures.

- The number of patients in hospitals in England

is now 40% higher than the first peak in April.

It is inescapable that the facts are changing

and we must change our response.

And so we have no choice

but to return to a national lockdown.

- [Narrator] While the new variants are concerning,

experts say that current prevention measures

should continue to work.

- This isn't something that's completing overcoming masks

or distancing and so if these measures

were put in place in more stricter,

more effective ways,

it'll be just as effective, if not more effective.

And the outcome may be that being a little bit more serious

about this will get transmission as a whole

to be reduced and I think that's an ideal.

- [Narrator] Scientists say the coronavirus pandemic

could be on the cusp of a major shift

but more research is needed

to know how severe the impact

of the new variants will be.

(dramatic music)