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July 18, 2022

What You Should Know About Omicron’s More Contagious Cousin—BA.5

What You Should Know About Omicron’s More Contagious Cousin—BA.5

The newest COVID subvariant spawned by Omicron, known as BA.5, is driving yet another surge in new cases and repeat infections across the United States and other parts of the world. 

Even those who recently recovered from COVID could catch BA.5 due to mutations that help it escape immunity from past infection and vaccination. It is now the dominant strain in the U.S., accounting for more than 65 percent of confirmed cases, while BA.4 made up 16 percent of infections, the U.S. Centers for Disease Control and Prevention (CDC) reports as of July 9.

“We have been watching this virus evolve rapidly,” said Ashish Jha, MD, MPH, the White House COVID-19 response coordinator in a July 12 news briefing. “We've been planning and preparing for this moment. And the message that I want to get across to the American people is this: BA.5 is something we're closely monitoring, and most importantly, we know how to manage it.”

What is different about BA.5?
When Omicron first emerged in November 2021, it quickly became dominant. It spread more easily than previous variants and proved to be less susceptible to existing COVID vaccines and antiviral treatments thanks to mutations—a lot of them.

Viruses’ genetic material mutates all the time as they replicate in an infected person. Most coronavirus mutations are actually harmful to the virus or have no effect either way. But mutations that make the virus more effective are likelier to persist and spread.

Now, roughly eight months later, Omicron’s cousin BA.5 and its sibling subvariant BA.4 have been shown to spread even faster due to more new mutations that allow it to evade immunity.

The subvariants are so elusive, in fact, that in a July 2022 study published in Nature, researchers discovered that BA.4 and BA.5 were 4.2 times more vaccine-resistant than BA.2 in people who received the Pfizer or Moderna mRNA vaccines.

“As the Omicron lineage has evolved over the past few months, each successive subvariant has seemingly become better and better at human transmission, as well as in antibody evasion,” according to the study’s authors. “Vigilance in our collective surveillance effort must be sustained.”

Are the BA.4 and BA.5 more severe?
BA.5 symptoms are like those of its Omicron predecessors. People who develop symptoms can experience fever, runny nose, coughing, sore throat, headaches, muscle pain, or fatigue.

“The good news is that the vast majority of breakthrough infections now are outpatient illnesses,” said Dean Blumberg, MD, chief of pediatric infectious diseases at UC Davis Children’s Hospital. “They are not resulting in the kind of severe illness that we saw earlier in the pandemic when no one had immunity, which led to increased hospitalizations and deaths.”

There is no evidence at this time that shows BA.5 is more virulent than previous variants, in large part because many people have developed a stronger immunity from vaccination and previous infection that help protect against severe illness, according to Maria Van Kerkhove, PhD, the World Health Organization’s COVID-19 technical lead.

“We have not seen an increased severity signal of BA.5 compared to other sub-lineages of Omicron, but … it’s still early,” Van Kerkhove said in a July 22 briefing. “What we want people to be concerned about or take careful consideration about is any sub-lineage, any variant of concern, any variant that is circulating. SARS-CoV-2, in whatever form it is, is a dangerous virus, but the positive is that we have tools that can prevent infection and tools that can prevent severe disease.”

What is being done?
The U.S. Food and Drug Administration (FDA) has asked Pfizer and Moderna to tweak their Omicron-adapted COVID vaccines for BA.4 and BA.5. The hope is that by acting now, an updated booster may be ready by mid-fall. The move could help bolster protection ahead of a new wave of infections in the coming months.

On July 12, the White House COVID-19 Response Team announced its strategy to manage the surge of BA.5., noting that it will continue working with state, local, and community leaders, facilities, and organizations to increase vaccinations and booster shots. Adults older than 50 and those with a weakened immune system are at higher risk for severe COVID. Health officials urge these high-risk groups to receive a second vaccine booster to bolster their immunity level.

The Biden Administration is also increasing its stockpile of treatments to manage symptoms of BA.5 infection, including Paxlovid, which has been shown to be 90 percent effective in reducing hospitalization or death. The federal government purchased 20 million courses of Paxlovid to make the therapy available to more people.

How you can protect yourself
BA.4 and BA.5’s enhanced ability to evade immune response may leave many people wondering whether the vaccines that are currently available are still effective. The short answer: Yes.

Although these sub-lineages are highly transmissible and infection rates are increasing, the fact remains that COVID vaccines and boosters are still the best defense against serious illness and death from the virus.

“The COVID-19 vaccines that are in use right now… are very effective at preventing severe disease and death, including against BA.4 and BA.5 and other sub-lineages of Omicron,” Van Kerkhove said. “This is what I want the public to hear.”

The best way to protect yourself from severe infection is to get vaccinated. People in the United States who are age 6 months and older are eligible to receive a COVID vaccine, and all those ages 5 and older are eligible for boosters. Adults ages 50 and older or kids and teens ages 12 and older who are moderately or severely immunocompromised are advised to get their second booster shot four months after their first booster. Those who are fully vaccinated should get their additional shot as soon as they are eligible.

People can also manage their risk of infection by following the best practices learned early-on in the pandemic: wear a well-fitted, high-quality face mask, wash your hands well and often with soap and water for at least 20 seconds, physically distance (at least 6 feet) from non-household members, and get tested if you suspect you’ve been exposed to COVID or develop symptoms.

If you test positive for COVID, isolate at home for at least 5 days, wear a well-fitting mask around people that live in your home, and do not travel. After 5 days, you may end your isolation if you have been fever-free for at least 24 hours and your symptoms are resolving or you are symptom-free. But continue to take precautions, such as wearing a mask and avoiding travel for another 5 days.

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