XBB.1.16 has been discovered in 33 countries. Will it trigger a new round of epidemic?

◎ Science and Technology Daily reporter Zhang Jiaxin

According to foreign media reports, the new coronavirus variant XBB.1.16 is spreading in multiple countries.

XBB.1.16 is a recombinant strain of the novel coronavirus Omicron, belonging to the XBB family, and is a hybrid of two different BA.2 sublineages. It was first reported on January 9 and designated as a "variant to be monitored (VUM)" by the World Health Organization (WHO) on March 22. In the folk, it is named "Arcturus".

So far, most cases of Arcturia have been mild in India, but it has been found in 32 other countries, including Singapore, the United States, Britain and Australia.

In July 2022, a medical technician in New York, USA, conducted a coronavirus nucleic acid test on a woman. Source: Columbia Broadcasting Corporation

On April 17, the WHO listed XBB.1.16 as a “variant of concern (VOI)”.

According to NBC on April 27, Ali Mokdad, a professor of global health at the University of Washington, believes that it is too early to predict how XBB.1.16 will develop. But what he has seen so far is reassuring. He said that he has not seen an increase in the number of hospitalizations, nor has he seen an increase in any indicators that worry doctors and experts.

Is XBB.1.16 more contagious?

Natalie Thornburg of the U.S. Centers for Disease Control and Prevention (CDC) said that compared with its predecessor, XBB.1.16 has only a few mutations on the coronavirus spike protein, fewer than the dozens of mutations that appeared in the original Omicron variant early in the pandemic.

According to CDC data, as of April 22, XBB.1.16 still accounted for slightly less than 10% of newly confirmed COVID-19 cases, although the proportion has been steadily increasing in recent weeks. Mokdad said XBB.1.16 is gradually replacing the variant XBB.1.5 that previously dominated the United States. Its increased transmissibility appears to be due to the subvariant's ability to escape immunity, but it is not deadly.

Peter Qinhong, a professor of infectious diseases at the University of California, San Francisco, said that apart from the increased transmissibility, XBB.1.16 is not much different from XBB.1.5 so far, which means that its pathogenicity and the effectiveness of the vaccine against it will not be much different.

The U.S. Capitol Hill website reported on April 27 that despite the increasing classification of subvariants, the WHO believes that Arcturus has no "additional public health risk" compared to XBB.1.5 and other descendants of Omicron. After XBB.1.16 was declared VOI, the WHO stated in its preliminary risk assessment that its global risk assessment was low based on the available evidence.

WHO officials observed that certain characteristics of Arcturus differed from those of other variants, making it more effective at evading immune responses, but no changes in severity were reported in countries or regions where the virus was spreading.

The World Health Organization logo displayed on an Android phone with a coronavirus illustration in the background. Image source: Live Pennsylvania website

What are the symptoms of XBB.1.16?

Dr. Mike Ryan, executive director of the World Health Organization's Health Emergencies Program, said XBB.1.16 does not appear to be as infectious as the earlier Omicron variant. "As far as I know, we have not seen different symptoms or changes in severity associated with this variant."

NBC reported that XBB.1.16 infection can cause a "new" symptom - conjunctivitis, or "pink eye". However, the World Health Organization has previously pointed out that this symptom is related to COVID-19 infection. As early as the spring of 2020, there were reports of itchy and painful eyes in patients infected with COVID-19. In May 2020, the American Association of Ophthalmologists pointed out that mild conjunctivitis may be a symptom of COVID-19 infection.

Qin Hong said that "pink eye" is not a new symptom of COVID-19 infection, but it may be more common than previously thought.

The Hill reported that although "pink eye" has been observed in some patients, experts warned against jumping to conclusions. "Careful study" is needed before declaring that the new symptoms are related to XBB.1.16.

Will XBB.1.16 cause a new trend?

In terms of the growth advantage of XBB.1.16, WHO described it as only "modest" compared to other variants. Since it was first reported in early January, the variant has only gradually increased around the world.

The UK Health Security Agency reported on April 21 that preliminary analysis showed that there was "no difference" in the ability of antibodies produced by vaccination to protect against XBB.1.16 compared to earlier XBB strains. Compared to the earlier XBB.1.5 variant, animal test data released by the WHO on April 17 found that XBB.1.16's ability to evade previous infection was "comparable" to that of the earlier XBB.1.5 variant.

CBS reported on the 27th that although XBB.1.16 was found in a surge of infections in India, it is still unclear what exact role the mutation of the variant played in driving this growth. India saw a "strikingly similar" surge in new coronavirus infections at the same time in 2021, making it difficult to figure out to what extent this epidemic is just a "seasonal effect."

The rate of increase in the number of people hospitalized for COVID-19 infection in the United States reached a low point in the spring of 2021 and 2022. Currently, COVID-19 infection indicators across the United States are continuing to decline and are approaching the lows of these two years. However, it is worth mentioning that highs reappeared in the summer of the previous two years.

Thornberg said COVID-19 infections have not yet fallen into a precise seasonal pattern, but over the past few years the trend has been a surge in late summer and early fall, and another surge in late winter.

Source: Science and Technology Daily

Editor: Wang Fan

Review: Julie

Final judge: Wang Yu