Omicron Photo: VCG

With concern rising among Chinese public that the currently prevalent XBB variant in Europe and the US may cause another round of infections in China even among those who had recovered from COVID-19, experts have confirmed that chances of reinfection with XBB in the short term are very slim for those who have recovered from BA.5.2 and BF.7 strains.

"XBB is a subvariant of Omicron, which was first discovered in India in August 2022. It is considered to be the recombination of two different Omicron subvariants BA.2.10.1 and BA.2.75. XBB has further evolved into XBB.1 and XBB.1.5, the latter of which is a variant strain that is rapidly rising in some countries in Europe and the US, and has become prevalent in some countries. But it seems that the symptoms caused by the strain are not particularly severe compared to other variants," Wang Xinyu, deputy director of infectious disease department in Huashan Hospital affiliated to Fudan University, told the Global Times on Tuesday. 

Wang said for those who have been infected with BA.5.2 or BF.7 and other Omicron variants, the chances of reinfection with XBB within a short period of time are very slim. Based on data collected in December 2022, the prevalent mutant strains in China are still dominated by BA.5.2 and BF.7. XBB is isolated from a very small number of cases, and is mainly imported from abroad. Symptoms of XBB cases and other variants do not appear to differ, according to Wang.

Previous media reports claimed that although Shanghai has detected the Omicron subvariants BQ.1 and XBB, experts said the two mutant strains were found in imported cases placed under closed-loop management and had not lead to local transmission.

Wang acknowledged public concern over XBB reportedly attacking the intestinal tract and causing brain fog disease.

Some people infected with the new mutant strains do have gastrointestinal symptoms, including vomiting and diarrhea. Diarrhea is not uncommon among symptoms other than the respiratory tract. According to foreign reports, XBB may also cause diarrhea, but nothing more serious, and XBB still mainly invades the respiratory tract, so "XBB mainly attacks the intestinal tract" is not true, Wang told the Global Times, noting that it's unnecessary for the public to hoard antidiarrheal and antibacterial drugs as diarrhea caused by COVID-19 is usually mild, and generally can be resolved on its own in a short period without drug treatment.

If diarrhea is severe, electrolytes water and oral rehydration are recommended, which are usually sufficient.

Although as a very rare complication of COVID-19, encephalitis does cause relatively severe symptoms, the probability is very small, so the public can rest assured. 

As for "brain fog disease," it is just an informal term to describe people who consciously forget things or have low work efficiency after being infected with COVID-19. It is not a specific medical diagnosis, and it is generally not treated as a sequela of COVID-19.

As some studies have pointed out that the new coronavirus neutralizing antibody has been completely ineffective against the new strain XBB, Wang said that the therapeutic effects of the existing COVID-19 neutralizing antibody drugs that have been marketed at home and abroad on the new strain XBB have indeed been greatly reduced, showing little to no therapeutic value. And that their use should be left to each clinician's judgment since such drugs are difficult to obtain in China, in this regard, the general impact in China is very limited.  

As long as the pandemic is not over, the mutant strains of the novel coronavirus around the world will continue to change, and new mutant strains will replace the old ones to become the prevalent virus strains. This is a rule. We shouldn't be overly anxious, Wang said.

"As public health and clinical medical workers, we should remain vigilant at all times, continuously monitor the prevalent local mutant strains, and at the same time strengthen the monitoring of the clinical symptoms of infected patients," the expert said, noting that if new variants are found to cause significant rising number of infections and increased fatality rate, it may be necessary to strengthen non-drug intervention measures again to avoid another wave of medical treatment peaks. 

"In fact, many countries have dynamically adjusted their prevention and control measures in this way," Wang said.