What We Know About Omicron Subvariants BA.4/5

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Microbiologist Esther Babady in her lab

Esther Babady is Director of MSK’s Clinical Microbiology Service.

There are many questions about the variants of COVID-19, and scientists are learning more every day. The Omicron subvariants BA.4/5 are circulating widely in the U.S. today.

Esther Babady, Chief of MSK’s Clinical Microbiology Service, is a nationally recognized leader in understanding variants and testing for COVID-19.

Here, Dr. Babady answers questions you may have about variants and how to protect yourself.

This information is about the Omicron subvariants BA.4/5.

Read about the updated (bivalent) vaccine, which targets Omicron subvariants BA.4/5 »

What are Omicron subvariants? What does it mean when a new subvariant emerges?

When scientists find variants and subvariants, it means the virus is changing as it persists within a person or moves from person to person throughout the population.

There are several members of the Omicron variant group. They all have different mutations in their genome, which means they have different characteristics.

The surge of COVID-19 cases in January and February 2022 was primarily driven by Omicron BA.1. Then, another surge in March, April, and May was driven by BA.2. Omicron subvariant BA.3 did not spread widely. Today, a large portion of cases of COVID-19 are caused by the BA.4/5 subvariants.

Variants and subvariants are expected and something that we plan for. As a science and healthcare community, we are focused on BA.4, BA.5, and other variants — but we’re also looking ahead to what could come next.

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What can I do to protect myself from Omicron BA.4/5, and other COVID-19 variants and subvariants?

There are several things you can do to protect yourself and your loved ones. We know that all of these actions slow the spread of COVID-19.

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Are BA.4/5 more contagious than other variants? Do these subvariants cause more severe disease?

These subvariants spread easily across the U.S. As cases rise, generally, hospitalizations and deaths also go up. However, there is no definitive proof that BA.4 or BA.5 subvariants cause more severe disease in people.

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Should I be worried about BA.4/5?

These subvariants should be taken seriously.

The Omicron variant group is labeled by the Centers for Disease Control and Prevention (CDC) as a “variant of concern.” The CDC says a variant of concern could have several possible attributes, including any or all of the following:

  • increased transmissibility
  • increased disease severity
  • decreased vaccine protection

Since BA.4/5 are part the Omicron variant group, they are also considered variants of concern.

Read more about how the CDC defines a variant of concern »

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Can the BA.4/5 subvariants be detected by current at-home diagnostic tests?

Yes. Current at-home diagnostic tests detected BA.4/5. Anecdotally, there have been cases of people who felt sick but still tested negative several times with at-home tests. This suggests a potential decrease in the sensitivity of some at-home tests.

However, that doesn’t mean you shouldn’t test. If you have symptoms or were exposed to someone with COVID-19, you should get a PCR test or consider testing twice per day with an at-home test.

If you are going to see someone who is at high risk for severe COVID-19, you should take an at-home test — even if you are feeling fine.

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If I already had COVID-19 recently, can I get sick again with the Omicron subvariant BA.4 or BA.5?

It’s possible. There have been cases of people who were infected just a few weeks ago and already have COVID-19 again. How frequently this happens is still under investigation. Infection with another COVID-19 subvariant may or may not provide natural immunity against BA.4 or BA.5. We need more data to fully understand this.

May 5, 2023

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