Unvaccinated people are not only at risk of catching Covid-19 - but also at risk of creating new variants, an infectious disease specialists say.
Unvaccinated people do more than merely risk their own health. They're also a risk to everyone if they become infected with coronavirus, infectious disease specialists said.
"Unvaccinated people are potential variant factories," Dr William Schaffner, a professor in the Division of Infectious Diseases at Vanderbilt University Medical Centre, told CNN.
"The more unvaccinated people there are, the more opportunities for the virus to multiply," Schaffner added, explaining how the multiplication of the virus can also lead to mutations and the creation of new variants.
"When it does, it mutates, and it could throw off a variant mutation that is even more serious down the road."
While not all mutations result in new variants, the expert explained that some mutations can give the virus an advantage such as better transmissibility and eventually make the virus strong enough to outcompete other viruses.
If a mutant version of a virus becomes strong enough, through multiplication, it becomes its own variant, as it has happened since the start of the pandemic.
"As mutations come up in viruses, the ones that persist are the ones that make it easier for the virus to spread in the population," Andrew Pekosz, a microbiologist and immunologist at the Johns Hopkins Bloomberg School of Public Health, also told CNN.
"Every time the viruses changes, that gives the virus a different platform to add more mutations. Now we have viruses that spread more efficiently."
If a virus is not able to spread, it is not able to mutate into stronger variants.
The Covid-19 pandemic has seen the appearance of variants all over the world, starting with the B.1.1.7, or Alpha variant, first spotted in England.
The B.1.351, or Beta variant, first appeared in South Africa, while the Delta Variant, B.1.617.2, was first detected in India.
There have also been new variants appearing first in the US, including the B.1.427 or Epsilon lineage first seen in California, and the B.1.526 or Eta variant first detected in New York.
According to the experts, we've already seen one variant spread further and become more deadly than the original strain of the virus.
The Delta variant, currently spreading around the globe, is set to become the dominant variant, due to its extremely high transmissibility.
The current vaccines being rolled out across the world protect against all the variants so far but experts warn that could change at any moment, if people do not get vaccinated and continue to give the virus the ability to multiply.
"The more we allow the virus to spread, the more opportunity the virus has to change," the World Health Organisation warned last month.
Populations of unvaccinated people, the experts say, give the virus the chance not only to spread but also to mutate, becoming less visible to the immune system.
"All it takes is one mutation in one person," Dr Philip Landrigan, an immunologist at Boston College, said.