As an increasing number of Americans become fully vaccinated against COVID-19, some health officials are concerned that the Delta variant, which can spread more easily and cause more severe disease than other strains, will have a deadly effect on communities that remain unvaccinated, CNN reports.

Initially identified in India, the Delta variant has been detected in 49 states as well as Washington, D.C., according to GISAID, an independent data sharing initiative, and the Hawaii Department of Health. 

Additionally, the US Centers for Disease Control and Prevention (CDC) has said there's a low chance people who are fully vaccinated may get infected with virus variants.

The effects of nearly any illness can be shortened or milder if one is fully vaccinated, but as officials promote this fact, they continue to emphasize that this information is directed towards patients who are "fully" vaccinated against COVID-19.

In other words, most U.S. health experts agree that the second shot is essential for maximum protection against variants.

"Please get your second shot," CDC Director Dr. Rochelle Walensky said Friday in an interview with the National Public Radio.

"What we do know is you get some protection from the first shot, but really that second shot gives you breadth and depth of vaccine coverage to really be able to tackle this Delta variant and other variants as well."

Citing CDC data, CNN reports that more than one in ten individuals in the US who received one dose of either the Pfizer/BioNTech or Moderna vaccine have missed their second dose.