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BA1

BA.1 is a sublineage of the SARS-CoV-2 Omicron variant, classified within the PANGO lineage B.1.1.529. It was among the first Omicron sublineages to spread globally after Omicron’s emergence in late 2021.

Origin and naming: The Omicron variant was first reported in late 2021 and designated a variant of

Mutations and properties: BA.1 carried numerous mutations in the spike protein relative to prior lineages. These

Epidemiology and impact: BA.1 circulated widely in many regions and was later outcompeted by other Omicron

See also: Omicron (variant), SARS-CoV-2 Omicron sublineages, PANGO lineage.

concern
by
the
World
Health
Organization.
BA.1
refers
to
one
of
the
initial
sublineages
within
Omicron,
notable
for
a
large
set
of
spike
protein
mutations
that
were
associated
with
increased
transmissibility
and
immune
evasion
compared
with
earlier
variants.
changes
contributed
to
higher
transmissibility
and
some
immune
escape,
while
vaccination
and
booster
doses
continued
to
reduce
the
risk
of
severe
disease.
sublineages,
such
as
BA.2.
Public
health
analyses
noted
the
high
transmissibility
of
Omicron
sublineages,
with
vaccines
remaining
a
key
factor
in
reducing
severe
outcomes
even
as
protection
against
infection
waned
over
time.