False: The XBB subvariant of COVID-19 is five times more virulent than the Delta variant.

By: Rajini KG
January 3 2023

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False: The XBB subvariant of COVID-19 is five times more virulent than the Delta variant.


The Verdict False

There is no evidence of an increase in severity of the disease with XBB. Like other Omicron subvariants, it is highly transmissible but less severe.

Claim ID 1e802f4d


On December 20, 2022, the Indian government issued fresh COVID-19 guidelines following the rise of coronavirus cases in China and other nations. State governments have been instructed to increase their level of vigilance and to prepare to carry out genome sequencing of positive case samples to monitor both current and new variants. Following this, a message related to the Omicron subvariant XBB started circulating on WhatsApp and went viral on Twitter and Facebook. The message claims that "the new variant of the COVID-Omicron XBB coronavirus is 5 times more virulent than the Delta variant." The message also claims that compared to the Delta variant, it has a greater mortality rate and includes a list of symptoms that supposedly come with an XBB infection.

However, this claim is baseless. The health ministries of countries including India, Singapore and New Zealand, as well as the World Health Organization (WHO), have found there is no evidence that XBB causes more severe illness.

In Fact

Two Omicron BA.2 lineages – BA.2.10.1 and BA.2.75 – combined to form the Omicron subvariant XBB. It is not a 'new' variant, as the message claims.

According to a statement by the Indian SARS-CoV-2 Genomics Consortium (INSACOG) published on October 28, 2022, XBB was initially discovered in Singapore and the United States in August 2022. It has since been found in several Indian states, before the current wave of cases in China. INSACOG added that there were no reports about any increase in the severity of disease or hospitalization associated with this variant. "Among the Indian patients the disease is mild like with other Omicron sub-lineages and no increase in severity is noted," the statement added.

Gagandeep Kang, a reputed Indian microbiologist and professor at Christian Medical College (CMC) Vellore, tweeted on December 23, 2022, that "In India as well, we already have XBB and BF.7 (the 2 being hyped as new monsters). They are, like all Omicron subvariants, very good at infecting people because they escape the immune response that prevents infection, but are not causing more severe disease than delta."

Speaking to Logically, Dr. Jacob T John, a retired professor who headed the departments of clinical virology and microbiology at CMC Vellore, also confirmed that "the XBB variant is no more severe than other Omicron variant. It is more infectious but not severe."

The Ministry of Health & Family Welfare of the Government of India has expressly cautioned against this claim, tweeting from its official handle on December 22: "This message is circulating in some WhatsApp groups regarding XBB variant of #COVID19. The message is #FAKE and #MISLEADING."

We also found that the Government of Singapore has previously dismissed similar claims about the XBB subvariant. On October 14, 2022, the Ministry of Health stated that a misleading article titled 'BREAKING! Singapore Is Under Attack By The New SARS-CoV-2 XBB Recombinant Variant With COVID-19 Infections And Hospitalizations Rising. Thailand Could Be Next!' was published by Thailand Medical News. The Singapore government dismissed this report and said, "There has been no evidence of XBB subvariant causing more severe illness than previous variants."

A report by New Zealand's Ministry of Health on the COVID-19 variants in circulation, dated October 20, 2022, mentions that the XBB subvariant was found in New Zealand in October 2022. It too notes that while XBB has demonstrated substantial immune evasion, indicating a rise in cases, there is no strong evidence of increased disease severity associated with it.

A November news brief by WebMD noted that XBB had begun to spread in the U.S. and was being actively tracked by the Centers for Disease Control (CDC). However, the report also quoted the director of the Center for Pathogen Evolution at the University of Cambridge, Derek Smith, who said: "There has been a rapid rise in XBB, but it doesn't look like it's particularly more severe than other variants." 

During a White House news briefing on November 25, 2022, Anthony Fauci MD, who recently stepped down as director of the National Institute of Allergy and Infectious Diseases in the U.S., had said that "countries which had a big XBB, they had an increase in cases, but they did not have a concomitant major increase in hospitalizations."

According to the WHO, in regional genomic monitoring, while more research is required, the data does not indicate significant variations in disease severity for XBB infections. It said that as of October 9, the subvariant had been found in 35 countries. In another report dated November 2022, the WHO stated that "sublineages of Omicron have much in common: they are all highly transmissible, replicate in the upper respiratory tract, and tend to cause less severe disease compared to previous variants of concern."

The Verdict

There is no evidence to support the claim that the XBB subvariant is five times more virulent than the Delta variant of COVID-19 and causes more severe infections and deaths. Several medical authorities have reported there has been no increase in disease severity or hospitalizations because of XBB infections. Therefore, we are marking this claim as false.

The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19, including symptoms, prevention, and available treatment, please refer to the World Health Organization or your national healthcare authority.

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