W
O
RL
D
H
EA
LT
H
O
RG
A
N
IZ
A
TI
O
N
C
LA
SS
IF
IC
AT
IO
N
O
F^
V
A
R
IA
N
T
S
20E
20G
20C
20D
20B
20A
19B
Mu
Lambda
Iota
Eta
Theta
Kappa
Gamma
Alpha
Epsilon
Beta
Delta
Feb 2021 Apr Jun Aug Oct
C
A
SE
Gamma S
Variants
of interest
Alpha
Beta 100%
0
BY MANUEL CANALES
AND PATRICIA HEALY
Early 2021 brought a glimpse of normal life as
COVID-19 vaccines began to be administered. But a
new threat was starting to emerge. Slight changes
to the virus’s genetic code were steering the
pandemic in even more dangerous directions.
INFECTION AND
INEQUITY AROUND
THE WORLD
Vaccine equity
Lower income countries, facing
challenges getting and distrib-
uting vaccines, have lower
vaccination rates. Until most
of the world is immune, public
health measures such as testing
and masking will remain vital.
Contagion
All viruses replicate. Some are
highly transmissible, having
evolved efficient methods to
spread. Human behavior also
contributes to local and travel-
related transmission.
ORIGINAL STRAIN
DELTA VARIANT
SHARE OF PEOPLE WHO HAVE
RECEIVED AT LEAST ONE DOSE
68%
63
31
2
High-income countries
Upper middle
Lower middle
Low
6 BILLION
VACCINE
SHOTS
GIVEN
Cooperative global efforts are
under way to distribute vaccines
more equitably and to boost this
number much higher in 2022.
The Delta variant
accounts for nearly
all new infections.
DATA THROUGH SEPTEMBER 2021
Some mutations give
the virus no advantage;
others lead to more
severe illness. They
can also make the virus
more infectious and bet-
ter at evading immunity.
VARIANTS OF CONCERN
Threat to public health
VARIANTS OF INTEREST
Risk to public health
VARIANTS UNDER MONITORING
Potential risk to public health