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By Lilly Cheng Immergluck, Professor of Microbiology via The Conversation

Professor of Microbiology via The Conversation

over 93 percent of COVID-19 cases in the U.S. at the end of July 2021

, questions arise about how to stay protected against evolving forms of the SARS-CoV-2 virus. Here, pediatrician and infectious disease specialist 

 of Morehouse School of Medicine answers some common questions about variants and what you can do to best protect yourself.

1) What are variants and how do they emerge?

 to adapt to their environment and improve their survival. Over the course of the pandemic, 

, the novel coronavirus that causes COVID-19, has mutated enough to change both its ability to spread through the population and its ability to infect people.

. The U.S. Centers for Disease Control and Prevention currently classifies variants into 

, listed in order of least to most concerning:

, but their definitions may differ from the CDC’s U.S.-based ones, as variant features and effects may differ by geographic location.

A variant may be more or less dangerous than other strains depending on the mutations in its genetic code. 

 like how contagious a viral variant is, how it interacts with the immune system or the severity of the symptoms it triggers. 

 is more transmissible than the original form of SARS-CoV-2. Studies show it’s somewhere between 

 than the virus that was most common at the start of the pandemic. Alpha also is more likely to cause severe disease, as indicated by 

increased rates of hospitalization and death

Even more extreme, the delta variant is reported to be 

 as previous strains and may cause even more severe disease among those who are unvaccinated. The 

 of those infected with delta — meaning the amount of virus detected from the nasal passages of an infected person — is also reported to be 

 than in those infected with the original form of SARS-CoV-2. Recent evidence also suggests that both 

unvaccinated and vaccinated people carry similar viral loads

, further contributing to the especially contagious nature of this variant.

3) Which variants are most common in the US?

Over the course of a few months, the delta variant has become the predominant strain in the U.S., accounting for 

the vast majority of COVID-19 cases at the end of July 2021

But there are regional variations across the country. As of July 31, the CDC estimated that the alpha variant represented over 3 percent of cases identified in a region of eight states that includes Georgia, Florida and Tennessee, compared with less than 1 percent in the region that includes Iowa, Kansas, Missouri and Nebraska. The 

 in cooperation with state health departments and other public health agencies. 

 from across the country are genetically sequenced each week to identify existing and new variants.

And new variants will likely continue to 

, for instance, is a sub-lineage of delta. The effects of this subvariant are yet to be determined.

4) How are vaccines holding up against variants?

Researchers are working to figure out how effective the 

three COVID-19 vaccines currently authorized for emergency use

 in the U.S. are at preventing infection from variants in “real-world” conditions where variant distribution and frequency constantly change. Several preliminary studies that have not yet been peer-reviewed suggest that these vaccines are 

still effective in preventing COVID-19-related serious infections and death

 are possible in those who are vaccinated. 

Older adults and those with immunocompromising conditions

 may be at increased risk to have these breakthrough infections. 

Thankfully, fully vaccinated individuals generally experience 

study analyzing COVID-19 cases in England

 estimated that two doses of the Pfizer BioNTech vaccine are 93.7 percent effective in preventing symptomatic disease from the alpha variant and 88 percent effective from delta. A different 

study in Ontario, Canada, that is not yet peer-reviewed

 reported that the Moderna vaccine is 92 percent effective in preventing symptomatic disease from alpha.

depends on a number of individual and external factors

Nearly all - 99.5 percent - of COVID-19 deaths

 in the U.S. over the past few months were among unvaccinated people.

 recommend that everyone wear a mask in areas of 

. More caution should especially be taken if you 

Another factor to consider is the level of community transmission and the proportion of unvaccinated people in your local community. For example, someone who lives in an area that is below the 

national average for COVID-19 vaccinations

 may have a higher chance of encountering someone who is unvaccinated — and so more likely to spread the coronavirus — than someone in an area with higher vaccination rates. 

How to wear a fabric mask safely - YouTube

Finally, there are still a significant number of people who are at high risk of COVID-19, including children. As of Aug. 3, 2021, 

only 29.1 percent of children ages 12 to 15

, and 40.4 percent of those ages 16 and 17, had been fully vaccinated. The American Academy of Pediatrics and the Children’s Hospital Association note that 

 had been reported as of Aug. 5. Children make up 14.3 percent of reported COVID-19 cases. If your child is unvaccinated, the best way you can protect them and other unvaccinated members of your household is to 

get yourself vaccinated and have everyone wear a mask in indoor public spaces

Guidelines provided by public health agencies are simply that – general guidelines. They are not tailored to be prescriptive for each individual and their personal risk assessments.

Vaccines remain the best protection against every strain of the novel coronavirus. But 

masking, social distancing and avoiding crowds and poorly ventilated indoor spaces

 add extra layers of protection against 

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COVID-19

Pediatrician and infectious disease specialist Dr. Lilly Cheng Immergluck of Morehouse School of Medicine answers some common questions.

Hannah Yang | MPR News

A young woman gets a vaccine at a table. 

What are COVID-19 variants and how can you stay safe as they spread? A doctor answers 5 questions

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