<s>
The	O
Zoe	B-Application
Health	I-Application
Study	I-Application
,	O
formerly	O
the	O
COVID	B-Application
Symptom	I-Application
Study	I-Application
,	O
is	O
a	O
health	O
research	O
project	O
of	O
British	O
company	O
Zoe	B-Application
Limited	I-Application
(	O
formerly	O
Zoe	B-Application
Global	I-Application
limited	I-Application
)	O
which	O
uses	O
a	O
mobile	B-Application
app	I-Application
that	O
runs	O
on	O
Android	B-Application
and	O
iOS	B-Application
.	O
</s>
<s>
The	O
app	O
was	O
created	O
in	O
2020	O
in	O
response	O
to	O
the	O
COVID-19	O
pandemic	O
,	O
in	O
a	O
collaboration	O
between	O
Zoe	B-Application
,	O
King	O
's	O
College	O
London	O
,	O
Guy	O
's	O
and	O
St	O
Thomas	O
 '	O
Hospitals	O
.	O
</s>
<s>
Zoe	B-Application
Limited	I-Application
also	O
provides	O
in	O
the	O
US	O
and	O
UK	O
,	O
as	O
a	O
separate	O
product	O
,	O
a	O
system	O
that	O
allows	O
people	O
to	O
analyse	O
their	O
unique	O
gut	O
,	O
blood	O
fat	O
and	O
blood	O
sugar	O
responses	O
to	O
food	O
,	O
saying	O
that	O
it	O
enables	O
people	O
to	O
"	O
make	O
the	O
best	O
decisions	O
for	O
your	O
own	O
health	O
&	O
weight	O
goals	O
"	O
.	O
</s>
<s>
In	O
the	O
early	O
months	O
of	O
2020	O
he	O
used	O
his	O
startup	O
company	O
ZOE	B-Application
Global	I-Application
Limited	I-Application
to	O
build	O
a	O
Covid	B-Application
Symptom	I-Application
Tracker	I-Application
app	O
in	O
collaboration	O
with	O
King	O
's	O
College	O
London	O
and	O
Guy	O
's	O
and	O
St	O
Thomas	O
 '	O
hospitals	O
.	O
</s>
<s>
By	O
May	O
2020	O
the	O
app	O
's	O
name	O
had	O
changed	O
to	O
COVID	B-Application
Symptom	I-Application
Study	I-Application
.	O
</s>
<s>
The	O
app	O
was	O
released	O
as	O
a	O
trial	O
for	O
5,000	O
twins	O
,	O
using	O
patients	O
involved	O
in	O
other	O
Zoe	B-Application
research	O
projects	O
.	O
</s>
<s>
The	O
app	O
entered	O
the	O
UK	O
Apple	B-Application
App	I-Application
Store	I-Application
and	O
Google	B-Application
Play	I-Application
Store	I-Application
on	O
24	O
March	O
,	O
and	O
the	O
US	O
App	O
and	O
Play	O
stores	O
on	O
29	O
March	O
.	O
</s>
<s>
In	O
May	O
2021	O
,	O
the	O
associated	O
company	O
name	O
was	O
changed	O
from	O
ZOE	B-Application
Global	I-Application
Limited	I-Application
to	O
ZOE	B-Application
Limited	I-Application
.	O
</s>
<s>
In	O
May	O
2022	O
,	O
ZOE	B-Application
announced	O
that	O
the	O
name	O
of	O
the	O
study	O
would	O
change	O
to	O
ZOE	B-Application
Health	I-Application
Study	I-Application
,	O
to	O
reflect	O
its	O
use	O
in	O
logging	O
symptoms	O
extending	O
beyond	O
those	O
of	O
COVID-19	O
.	O
</s>
<s>
The	O
COVID	B-Application
Symptom	I-Application
Study	I-Application
requires	O
users	O
to	O
give	O
their	O
location	O
.	O
</s>
<s>
The	O
app	O
does	O
not	O
have	O
any	O
contact	B-Protocol
tracing	I-Protocol
functionality	O
.	O
</s>
