Arcturus: understand variant of Covid linked to conjunctivitis – 02/05/2023 – Health

The state of São Paulo confirmed this Monday (1st) the first case of the Arcturus subvariant of Covid-19. Known to be related to conjunctivitis in infected people, the strain was first identified in January 2023 and has since spread to different countries.

In March, Arcturus was considered by the WHO (World Health Organization) as a variant under monitoring. Less than a month later, the institution indicated that Arcturus was a variant of interest, which means a degree of greater concern.

This Tuesday (2), the São Paulo City Hall announced that it will extend vaccination with the bivalent Pfizer to the public aged 40 or over starting this Wednesday (3).

LEARN MORE ABOUT THE ARCTURUS SUBVARIANT

What is it?

With the technical name XBB.1.16, Arcturus was first recorded on January 9, 2023 and is descended from XBB, an omicron-variant lineage. It has a profile similar to that of XBB.1.5, a subvariant that scared the WHO when it was discovered, due to its transmission capacity. Arcturus, however, harbors two different mutations in the S protein, used by the virus to enter human cells.

The country with the most registered cases is India, but another 36 have also sequenced the strain, according to the latest WHO epidemiological report that considers data up to April 23.

The strain was considered a variant of interest in April 2023. According to the WHO, a strain is classified in this way when it has mutations that can affect characteristics such as transmissibility, virulence or antibody escape. Furthermore, the strain needs to have an increase in its spread in different regions of the world, causing an increase in the number of cases, to be considered of interest.

What are the symptoms?

Arcturus can cause the already known symptoms of Covid-19, such as fever, cough, pain and breathing problems. One of the characteristics that draws attention, however, is that Arcturus is related to the appearance of conjunctivitis in those infected.

Fernando Spilki, virologist and coordinator of the Rede Corona-omica BR-MCTI genomic sequencing project, says that there are reports in India and in other countries of the relationship between Arcturus and ocular inflammation, especially in children. He says, however, that a more thorough evaluation is needed, because this symptom has already been seen before. “Sporadic cases of conjunctivitis have been reported since 2020”, he says.

But the symptom information can already be useful for people to be aware in case of suspected infection by the coronavirus.

Does it cause more serious conditions?

Arcturus has similarities to XBB.1.5 – and that goes for the protection afforded by vaccines or previous infections as well.

A WHO document that evaluated Arcturus classified it as moderate risk. The conclusion is based in part on a pre-print study (when not published in a scientific journal reviewed by other specialists) which observed that there was no difference in the degree of immune escape between Arcturus and other subvariants already registered, such as XBB. 1.5 and XBB.1.

But this degree is not an indication that the strain necessarily causes more severe cases of the disease. In India, for example, the circulation of Arcturus did not cause an increase in hospitalizations, nor a greater need for the use of mechanical ventilation in a population in which approximately 70% had already taken some booster dose of vaccine against Covid-19.

“Available evidence does not suggest that XBB.1.16 poses an additional risk to public health than other circulating omicron-derived lineages,” summarizes the WHO in its risk assessment of the subvariant Arcturus.

Is the transmission bigger?

The same pre-print study that concluded that Arcturus did not differ for the immune system observed that the variant can cause a greater number of cases compared to other strains, such as XBB.1.5 itself.

The point is also seen in the risk report made by the WHO. The organization advises that the variant can “spread globally and lead to an increase in the incidence of cases”. The very classification of Arcturus as a variant of interest is an indication that it already spreads in different regions and causes new cases.

Therefore, the agency recommends that countries pay attention to the degree of dissemination of the strain and make this information available for a constant assessment of its impacts.

What does Arcturus represent for Brazil?

The first recorded case of Arcturus may cause concern, but Spilki says it’s important to wait a little longer to understand its impacts. “It is still too early to say what it is and what the degree of dissemination of this variant will be.”

The virologist claims that data from samples from past weeks do not indicate a degree of dissemination of the strain. However, this finding may change based on new analyses.

According to Spilki, with the announcement of the confirmed case, it is expected that the sequencing of past samples will increase to see if there have already been other infections of the strain in the country. And he says sequencing over the next few weeks will also be needed to assess the degree of spread.

The expert also points out that the increase in cases of the Arcturus subvariant in other countries does not necessarily mean that this will occur in Brazil. “In India, for example, it spread greatly, but of course we have our own dynamics in Brazil. The same panorama is not always repeated”, he concludes.