Everything You Need to Know About Arcturus, the New COVID Variant

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  • Arcturus, or XBB.1.16, is a new Omicron subvariant that is being monitored by the World Health Organization.

  • The new subvariant is behind a recent COVID-19 surge in India and has been found in the U.S.

  • Experts explain how this new subvariant is different from previous variants of interest.


Infectious disease experts and public health officials alike are on alert since the World Health Organization (WHO) announced a new COVID-19 variant of interest, XBB.1.16, also known as Arcturus. WHO is monitoring the new subvariant of omicron that has been detected in over 20 countries—including the U.S.—and is contributing to a recent surge of COVID-19 cases in India.

While cases of this new variant are still low in the U.S., the rapid spread of new infections in India, as well as in some other countries, sparks some curiosity into how XBB.1.16, or Arcturus, is different from the long line of existing Omicron subvariants.

So, what’s the deal with XBB.1.16 and how can it potentially impact your risk of contracting COVID-19? Experts explain what you need to know to stay safe.

What is the Arcturus variant, or XBB.1.16?

The Arcturus variant, or the XBB.1.16, is a subvariant of Omicron and part of the new class of XBB subvariants. It’s spreading fast in India, but in the other countries, it hasn’t taken off in the same way, explains Willaim Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine.

According to WHO, XBB.1.16 is a recombinant of BA.2.10.1 and BA.2.75 and shares a mutation with XBB.1.5. The mutations of this new variant have been associated with signs of increased transmissibility and a higher degree of infection. As of 27 March, XBB.1.16 sequences have been reported from 21 countries. However, so far reports do not indicate a rise in hospitalizations, ICU admissions, or deaths due to XBB.1.16.

How contagious is Arcturus?

It does appear, because of its mutation in the spike protein, that the Arcturus variant is more infectious and so that accounts for some of its spread in India, says Dr. Schaffner. However, “It does not appear to produce more severe disease, so for the moment it is a variant of interest and not a variant of concern,” he explains.

This variant is also likely more able to avoid prior immunity from a previous infection, (again, since it shows a mutation in the spike protein) rendering it more contagious than prior variants, notes Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security.

How can I distinguish Arcturus from other variants?

There is some data that is coming out that suggests that perhaps the spectrum of its symptoms may have some distinctive components, says Dr. Schaffner. XBB.1.16 “likes to produce more high fever, which is not always very prominent in COVID.” He adds that this variant also produces the usual kind of cough seen with previous COVID-19 variants.

But particularly in children, there seems to be a tell-tale symptom of this variant that hasn’t surfaced in its predecessors. “It seems to be producing more conjunctivitis, and inflammation of the insides of the eyelids, which can be very itchy and make the eye look red,” explains Dr. Schaffner.

Apart from some anecdotal reports of conjunctivitis and pink eye associated with Arcturus, this variant still presents very similarly to other Omicron variants, notes Dr. Adalja.

Arcturus symptoms

As mentioned above, there does seem to be a higher trend of the below XBB.1.16, or Arcturus, symptoms:

  • Higher fever in those infected

  • Some cases of conjunctivitis, particularly in children

However, for the most part, the symptoms of COVID-19 that you are familiar with are also symptoms of this Arcturus variant.

According to the Center for Disease Control and Prevention (CDC), the most common symptoms of COVID-19, are still:

  • Fever or chills

  • Cough

  • Shortness of breath or difficulty breathing

  • Fatigue

  • Muscle or body aches

  • Headache

  • New loss of taste or smell

  • Sore throat

  • Congestion or runny nose

  • Nausea or vomiting

  • Diarrhea

Is there a vaccine for Arcturus?

Whether you’re eligible for another booster yet or not, it’s common to question if the existing vaccines will defend against new variants. As it stands, it’s still too early to know just how protective the current vaccine formulations will be against XBB.1.16.

Researchers are currently making some distinctions between what’s in the vaccine and this variant, but that doesn’t always translate directly into protection, explains Dr. Schaffner. Still, getting your COVID-19 vaccine can decrease your risk for any severe infection. “The vaccine so far, in all of these other Omicron subvariants, has continued to provide pretty solid protection against severe disease,” says Dr. Schaffner.

As far as treating infections, the treatments that we have right now, such as Paxlovid, should work just fine with this new subvariant, says Dr. Schaffner.

Does Arcturus increase my risk for long COVID?

It’s much too early to say if this variant is more or less likely to lead to long COVID, says Dr. Schaffner.

That said, Omicron variants tend to cause less cases of long COVID, especially in vaccinated populations, notes Dr. Adalja. Also, repeat infections—and most people have had at least one infection by now—are less likely to cause long COVID as well, he adds.

The bottom line

Keeping track of all of the different subvariants these days can be overwhelming and at times, confusing. Dr. Adalja reminds us that these subvariants “are all versions of Omicron and don’t have the ability to heighten the risk of severe disease,” so there’s no need to worry too much over another subvariant yet.

This article is accurate as of press time. However, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC and WHO to stay informed on the latest news. Always talk to your doctor for professional medical advice.

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