Illustration: Needle in COVID molecule

The appearance of a new COVID-19 variant is not unique — variants occur in all viruses over time. And the scientists studying the disease and developing COVID vaccines always anticipated that new strains would continue to evolve.

COVID-19 variants began to emerge as early as summer 2020, and several more were identified throughout 2021.

By this year’s end, the Omicron variant began spreading worldwide, as the Delta variant was still causing significant illness, particularly among people who are not yet vaccinated.

With each new variant, the COVID vaccines and their boosters remain our most powerful tool to fight all the strains of COVID-19 because the vaccines continue to significantly reduce the severity of the illness.


Still deciding about the vaccine or know someone who is? See these 7 reasons to get the vaccine.


What Is a Variant Virus?

A variant occurs when the virus mutates, or changes, as it replicates and creates a slightly different version of itself. Sometimes, these variant strains just disappear; these are the viruses that don't make the news and scientists are not worried about them.

Occasionally, a strain becomes a “variant of concern” when it is able to survive better than the original virus or previous variants of concern.

They can become more easily passed from one person to another than the original strain or variants. They could also become more or less likely to cause serious illness.

Variants of Concern

Since late 2020, there have been a number of variants that circulated widely in the United States, including Alpha, Gamma and Beta. By late 2021, the two most significant variants are Delta and Omicron.

Delta (B.1.617.2) – Initially identified in India in late 2020, this variant was the most highly transmissible of the variants identified at that point. It caused more severe illness than other variants. Since August 2021, Delta had been the dominant variant causing infections in the United States.

Omicron (B.1.1.529) - First identified in Botswana and South Africa, the Omicron variant is likely to spread more easily than the original virus.

It is not yet clear how much more easily Omicron spreads compared to Delta, but in only three weeks, the Omicron variant has surpassed the Delta variant as the predominant virus infecting people in the United States.

  • In early November 2021, the first Omicron cases were traced.
  • On December 1, 2021, Omicron was first detected in the United States and in Maryland two days later.
  • On December 20, 2021, the CDC reported that Omicron represents 73 percent of new infections in the United States.

At this time, evidence regarding the severity of COVID-19 illness it causes is still being evaluated.

Do the Vaccines Work Against the New Strains?

The simple answer is yes.

At this time, there is no evidence to suggest that these or any other variants of the COVID-19 virus are completely resistant to the current vaccines. Vaccination and booster doses reduce the risk of hospitalization and death from COVID-19 infection.

The COVID vaccines are highly effective.

The effectiveness of the current COVID vaccines is quite high. In fact, it is much higher than some other vaccines we commonly receive. As a reminder, the annual flu vaccine has an effectiveness around 40-60 percent from year to year.

The current vaccines cause a powerful immune response that makes them highly protective, even if there is a drop in antibody strength. Antibodies are not the only part of the vaccines that makes them work. There are also T cells and memory B cells and other types of antibodies.

COVID boosters increase immune response.

According to the Centers for Disease Control, data from clinical trials showed that a booster shot increased the body’s immune response. With an increased immune response, people should have improved protection against getting infected with COVID-19, including the Delta variant. Clinical trials also showed that a booster shot helped prevent COVID cases in which symptoms developed.

The vaccines prevent hospitalization and death.

All of the current vaccines are highly effective in preventing hospitalization and death.

This is a critical point. Not only will the vaccine save lives, it will help relieve the strain on healthcare systems across the country

The vaccines help stop new variants.

As we vaccinate and boost as many people as possible, as quickly as possible, we can help stop the spread of the coronavirus. A decrease in transmission of the virus means fewer opportunities for it to mutate, which can help prevent the emergence of any other variants.

The vaccines can be updated to be more effective.

Research continues on all the COVID-19 vaccines. If necessary, future vaccines may need to be tweaked, similar to the flu vaccine every year. All vaccine manufacturers are continuing to study the effectiveness of the vaccines and are already looking at what a booster might look like in the future.

Reducing the Spread of COVID: Flatten the Curve

As COVID hospitalization continue to rise, the best way to “flatten the curve” and protect yourself and others from the virus is to get the vaccine.

Wearing a mask and social distancing are important to protect yourself and prevent spread. The vast majority of COVID-19 hospitalizations around the country right now are among unvaccinated people. However, everyone should follow all masking guidelines, regardless of vaccination status.

Updated 12/21/2021


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