National Geographic - USA (2022-01)

20F

19A

Original strain Variant

Protein

spike

RNA

Dec 2019 Feb 2020 Apr Jun Aug Oct Dec

Variants under

monitoring

SMALL CHANGES,

BIG PROBLEMS

The Delta variant’s rapid spread—despite

changes in less than 0.5 percent of its

genome—took scientists by surprise. Within

months of when the first mutation was

detected, in October 2020, the Delta variant

had quickly outpaced all other variants.

SOURCES: STUART C. RAY, JOHNS HOPKINS U. SCHOOL OF MEDICINE; EMILY N. POND, JOHNS HOPKINS CORONAVIRUS RESOURCE

CENTER; ALBA GRIFONI, LA JOLLA INSTITUTE; DANIEL S. CHERTOW, NIH; GISAID; NEXTSTRAIN; WHO; CDC; OUR WORLD IN DATA

An evolving threat

Scientists can identify transmission trends when they

study SARS-CoV-2 genomes. The genetic lineages of

the sampled genomes with mutations all link back

to the original virus first identified in Wuhan, China.

Mutations in early 2020, thought to increase the virus’s

transmissibility, were a harbinger of what was to come.

COVID-19 injects a strand

of replication instructions—

its RNA genome—into host

cells. Any naturally occurring

errors are called mutations.

A virus with a mutation

that changes its behavior

or efficiency is called

a variant.

This chart shows nearly

4,000 genomes (dots) sampled

from coronavirus infections

since the pandemic began.

January 7, 2020

The COVID-19

genome is isolated.

Original

strain

May 2020

A change in its

spike protein makes

it more infectious.

SHARE OF

COVID-19

VARIANTS,

GLOBAL CASES