Throughout the COVID-19 pandemic, scientists
have said that the virus changes very quickly.
New variants may change the way we respond to the pandemic.
But how do we know that the virus changes,
creating new variants like Delta or Omicron
The answer is genomic surveillance, a process where scientists gather
genetic sequence data from representative populations
to detect new variants and monitor trends in circulating variants.
Scientists around the world have used genomic surveillance
to track other viruses like Ebola or flu
throughout the COVID-19 pandemic.
Scientists have used these same methods to monitor changes
to SARS-CoV-2, the virus that causes COVID-19.
So how does this work?
A random selection of positive viral samples is
used as part of a coordinated surveillance effort.
Scientists gather the samples,
determine the genetic sequence in that sample, and then analyze
and compare it to other sequences in a large public database.
There are three main components of genomic surveillance.
One, genomic sequencing
Two, compiling and analyzing sequence data.
Three, Publishing findings and advising public health professionals.
When a person tests positive on a PCR based test.
The sample may be sent from the testing laboratory
to another laboratory to sequence or decode
the virus's genetic material.
This sample never includes the patient's personal information, and results
are used for surveillance only, not for diagnostic or clinical purposes.
The sequencing process maps out the genome of the virus,
presenting the scientists with a fingerprint of that virus
that can be corrected, raised and compared to other viral sequences.
Laboratories both in the United States and around the world
upload these sequences into public databases.
A key takeaway from the COVID 19 pandemic
is the importance of having large collaborative groups of scientists
who can look at the same data and agree on appropriate public health actions.
Genomic surveillance helps scientists do two things
one, identify key mutations that may change the virus's behavior
or the effectiveness of treatments or vaccines.
Two track genetic mutations within the virus as it replicates
and changes into new lineages and sub lineages.
Genomic surveillance provides valuable information
to public health professionals, which they use to make decisions
about how to respond to the COVID-19 pandemic.
If a variant emerges that causes more severe disease
like the Delta variant, genomic surveillance will help scientists
understand where and how fast that variant is spreading.
As a result, you may hear guidance
changes to recommended personal protective measures,
or that another vaccine booster is recommended.
By detecting specific mutations in the genome, scientists can also monitor
for variants that may be more resistant to certain treatments.
When they are, scientists communicate with doctors
to ensure that effective treatments are used appropriately to treat patients.
It's important for us
at CDC to provide transparent, timely and critical information
that will help drive public health decision making.
CDC publishes SARS-CoV-2 variants circulating in the United States
and the proportion of each variant causing infections by region.
On the CDC COVID Data Tracker, we also provide weekly
updates in the COVID Data Tracker Weekly Review.
CDC will continue to monitor
emerging variants, assess the threat they may pose and communicate
any implications to public health.