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COVID-19 Variants

Omicron Variant

First Case


On November 24, 2021, officials at the San Diego County Health and Human Services Agency, working in collaboration with scientists at the University of California San Diego and Scripps Research, have announced the second confirmed case — and first locally acquired infection — of the Omicron Variant of SARS-CoV-2, the virus that causes COVID-19. The First Carrier of the Omicron Variant in the U.S. was a traveler who returned from South Africa on November 22, 2021.

On November 26, 2021, the World Health Organization (WHO) classified a new variant, B.1.1.529, as a Variant of Concern, naming it Omicron, and on November 30, 2021, the United States also classified it as a Variant of Concern. As of December 20, 2021, Omicron has been detected in most states and territories and is increasing the number of COVID-19 cases. Not to mention, on December 22, 2021, the Omicron Variant surpassed the Delta Variant’s peak for the Average Daily Cases.

Omicron Drives U.S. Virus Cases Past Delta’s Peak.

Information about the Omicron Variant (Omicron vs. Delta)

The Omicron Variant has many mutations, or changes, in the spike protein, the part of the virus that attaches to human cells and influences how COVID-19 spreads. Omicron appears to be more contagious than the Delta Variant and has become the predominant strain more quickly. In addition, Omicron may cause more reinfection in people who have previously had COVID-19 and more breakthrough infections in vaccinated people than previous variants.

Compared to the Delta Variant, the Omicron Variant is 2-3 times more easily transmitted between individuals. Omicron is now the dominant strain of the coronavirus in the U.S. So far, it seems like infections caused by Omicron are less severe compared to Delta and previous variants. However, the number of people needing hospitalization will likely be higher due to the increase in the total number of people infected.

Structure of the SARS-CoV-2 Omicron Variant


Many patients with Omicron have a variety of symptoms that resolve quickly and don't require hospital care, NPR reported. Physicians told the news publication that Omicron cases frequently look like ordinary upper respiratory infections. "It's mostly that runny nose, sore throat, and nasal congestion," said John Vanchiere, MD, Ph.D., associate director of the Center for Emerging Viral Threats at Ochsner LSU Health Shreveport (La.). "The cough is milder [than previous variants] if there's any cough at all, and fever seems to be a little less common," he added.

According to a CDC analysis of the first 43 cases investigated in the U.S, the four most common symptoms of the Omicron variant are cough, fatigue, congestion, and runny nose. The CDC's list of COVID-19 symptoms includes fatigue, muscle or body aches, headache, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea. Asymptomatic infections are also common. Early data from the U.K. found fever and cough aren't as prevalent with Omicron, finding the five most common symptoms to be a runny nose, headache, fatigue, sneezing, and sore throat. A sore throat may be a predictor of Omicron among mild breakthrough cases, NBC Chicago reported Jan. 11.

Comparing symptoms, Omicron manifests itself somewhat similarly to previous COVID-19 strains, but with some shifts. “Omicron looks like much more of an upper respiratory tract infection,” says Dr. Diego Hijano, a pediatric infectious disease specialist at St. Jude Children's Research Hospital in Memphis, Tennessee. Patients are experiencing a lot of nasal congestion, stuffy nose, sore throat, fatigue, headaches, sneezing, and cough. With Omicron in particular, he adds that scratchy throat is gaining traction as a frequently reported symptom.

An Omicron-Infected Doctor

Delta Variant

First Case

First identified in India in late 2020, Delta swept rapidly through that country and Great Britain before reaching the U.S., where it quickly surged. Until mid-December, it was the predominant SARS CoV-2 variant, accounting for more than 99% of COVID-19 cases (at the time) and leading to an overwhelming increase in hospitalizations in some states. (Omicron is now the predominant variant in the U.S.)

On May 20, the University of Texas Southwestern Medical Center announced it had identified the first two cases of Delta in North Texas using PCR testing. It called the findings "concerning" because the variant was believed to be more infectious than previousvariants of COVID. At that time, the U.K. variant known as B.1.1.7 was still the dominant strain in the region. Two cases in Louisiana were reported the next day. Then other counties and states started reporting cases, too.

In mid-June, Hawaii health officials confirmed the presence of Delta there in one individual. Later that month, officials in Orange County, Florida, announced they had detected a dozen cases of the then-new variant. By July 1, CNN reported that Delta had been detected in all 50 states as well as Washington, D.C.

Spikes of the Delta Variant Across the U.S. States.

Information about the Delta Variant

The health agency states that Delta is nearly twice as contagious as previous variants of the virus; potentially causes more severe illness than previous strains in unvaccinated people, based on two different studies; and fully vaccinated people with a Delta breakthrough infection can spread the virus to others—though vaccinated people appear to be infectious for less time than unvaccinated people.

In communities with lower vaccination rates, particularly rural areas with limited access to care, the Delta variant could be even more damaging. This is already being seen around the world in poorer countries where the COVID-19 vaccine isn't as accessible. Health experts say the impact could be felt for decades to come.

As of July 22, nearly 80% of UC Davis Health patients who tested positive for COVID-19 had the Delta variant. According to the CDC during the same week, the Delta variant accounted for more than 80% of new cases in the U.S. Health experts say it's typical for a new strain of a virus to be more contagious because it often becomes much more efficient and easily transmitted.

Accepted 3D Structure of the Delta Variant (COVID-19 Virus).


The symptoms of the Delta variant appear to be the same as the original variant of COVID-19. However, physicians are seeing people getting sicker quicker, especially younger people. Recent research found that the Delta variant grows more rapidly – and too much greater levels – in the respiratory tract. Not to mention, the Delta Variant is found to cause more cold-like symptoms.

"Headache, sore throat, runny nose, and fever are present based on the most recent surveys in the U.K., where more than 90% of the cases are due to the delta strain," Dr. Inci Yildirim, a Yale Medicine pediatric infectious diseases specialist said when the strain was first detected earlier this year.

When a vaccinated person tests positive for COVID-19, most either have no symptoms or have very mild symptoms, and it rarely results in hospitalization or death. Their symptoms are more like those of a common cold, such as cough, fever, or headache, with the addition of a significant loss of smell.

A Delta Identified Patient Hospitalized.

Treatment + Prevention

6 Feet Protocol

In general, CDC recommends people who are not fully vaccinated maintain a physical distance of at least 6 feet from other people who are not in their household. However, several studies from the 2020-2021 school year show low COVID-19 transmission levels among students in schools that had less than 6 feet of physical distance when the school implemented and layered other prevention strategies, such as the use of masks.

Inside your home: Avoid close contact with people who are sick, if possible. If possible, maintain 6 feet between the person who is sick and other household members. If you are taking care of someone who is sick, make sure you properly wear a well-fitting mask and follow other steps to protect yourself.

Indoors in public: If you are not up to date on COVID-19 vaccines, stay at least 6 feet away from other people, especially if you are at higher risk of getting very sick with COVID-19.

The 6 Feet Protocol Being Implemented.


Today, CDC is endorsing the Advisory Committee on Immunization Practices (ACIP) recommendation to expand eligibility of booster doses to those 12 to 15 years old. CDC now recommends that adolescents aged 12 to 17 years old should receive a booster shot 5 months after their initial Pfizer-BioNTech vaccination series. At this time, only the Pfizer-BioNTech COVID-19 vaccine is authorized and recommended for adolescents aged 12-17.

Data show that COVID-19 boosters help broaden and strengthen protection against Omicron and other SARS-CoV-2 variants. ACIP reviewed the available safety data following the administration of over 25 million vaccine doses in adolescents; COVID-19 vaccines are safe and effective.

COVID-19 vaccines are being monitored for safety with the most comprehensive and intense safety monitoring program in U.S. history. CDC monitors the safety of all COVID-19 vaccines after the vaccines are authorized or approved for use, including the risk of myocarditis in children ages 5 through 11 years.

Cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the outer lining of the heart) have been reported after the Pfizer-BioNTech COVID-19 vaccination of children ages 12–17 years. These reactions are rare; in one study, the risk of myocarditis after the second dose of Pfizer-BioNTech in the week following vaccination was around 54 cases per million doses administered to males aged 12–17 years.

Possibility for Vaccination for Specific Age Groups.


Face masks combined with other preventive measures, such as getting vaccinated, frequent hand-washing, and physical distancing can help slow the spread of the virus that causes COVID-19.

The U.S. Centers for Disease Control and Prevention (CDC) recommends masks for the general public. If you’re fully vaccinated and are in an area with a high number of new COVID-19 cases, the CDC recommends wearing a mask indoors in public and outdoors in crowded areas or when you are in close contact with unvaccinated people. People who haven’t been fully vaccinated should wear face masks indoors and outdoors where there is a high risk of COVID-19 transmissions, such as crowded events or large gatherings.

The CDC says that you should wear the most protective mask possible that you'll wear regularly and that fits. Respirators such as nonsurgical N95s give the most protection. KN95s and medical masks provide the next highest level of protection. Cloth masks provide less protection. The CDC says that surgical N95 masks should be reserved for health care providers.

Standard Face Masks.



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