Will the continuous detection of new variants in China cause the second round of domestic epidemic peaks?
"'Powerful' new strains do not necessarily cause new transmission"
According to the latest data from China CDC, from December 2022, 12 to April 1, 2023, a total of 4,13 local cases of new coronavirus genome effective sequences were reported nationwide, all of which were Omicron variants, covering 31434 evolutionary branches. A total of 106 cases of the variant of indigenous concern were detected, including XBB.328.1, also known as Arcturus, which has recently attracted much attention. This new variant is considered the most transmissible, and symptoms such as conjunctivitis have been reported.
Which variants are worth noting? Will it cause the second round of epidemic peaks in China? Is conjunctivitis caused by Arcturus a new feature of the new crown? On April 4, the Beijing News contacted domestic public health and infectious disease experts to analyze the latest monitoring results.
Professor Sun Yamin of the Institute of Public Health and Health of Nankai University told the Beijing News that it is not a "powerful" new strain that necessarily causes new transmission. Although XBB spreads quickly and has strong immune escape, the real-time transmission coefficient in China is not high and is at a low epidemic level. Due to population immunity, it is difficult for new viruses to form as rapid as before.
Follow-up question 1
How strong is XBB.1.16?
Among the many variants of concern, XBB.1.16 has generated a great deal of discussion. The strain was first detected in India in late January. The WHO declared XBB.1.3 a "variant under surveillance" in late March, according to the British Daily Mail, calling it the most transmissible variant of the new crown to date. A study by the University of Tokyo in Japan showed that XBB.1.16 was about 1.16 to 1.1 times more efficient than XBB.5 and XBB.1.17 strains.
Li Tong, chief physician of the Department of Respiratory and Infectious Diseases of Beijing You'an Hospital affiliated to Capital Medical University, once said that in terms of the characteristics of the virus, XBB.1.16 is more transmissible than the previous variants, especially for people who have not been infected with the new crown, have not been vaccinated, and lack targeted immunity. In terms of pathogenicity, no significant changes have been observed.
However, Li Tong once believed that the global population is now generally vaccinated against the new crown or has a history of infection, and for the vast majority of people, it can still prevent infection with the new strain. As far as the domestic situation is concerned, most citizens have not been infected for more than half a year in the last round and are still immune to the new crown variant.
Follow-up question 2
Is conjunctivitis the result of a new strain variation?
Li Tong once introduced that since the emergence of the new crown virus, there have been reports of conjunctivitis. Conjunctivitis has always been included in the monitoring of new crown symptoms. Whether XXB.1.16 is more likely to have conjunctivitis than other strains, there is still relatively little data, but it comes from the feelings of some doctors abroad, and further observation is needed.
In addition to the new coronavirus, other pathogens such as influenza virus and adenovirus can cause conjunctivitis, which causes many conjunctivitis. When the weather warms up, conjunctivitis from various causes also increases.
In our country, there are not many cases of conjunctivitis caused by the new crown, and the treatment is generally prescribed by an ophthalmologist. If conjunctivitis occurs during the new crown epidemic season, be alert to whether you are infected with the new crown, especially for people who have not been impotent before, nucleic acid testing can be performed.
Follow-up question 3
New variants continue to be detected, will the second round of peaks come?
The latest number of new crown nucleic acid positives, antigen positives, outpatient and fever outpatient positives announced by China CDC has not been significantly upward in the near future. However, new variants continue to be detected locally, and there are many new variants such as XBB.1.5 and XBB.1.16 with a high proportion of epidemics in other countries, will the second round of peaks follow?
"There will always be a branch of the virus that is the main one in the population, after all, the new crown is still circulating, but as long as the proportion of new infections in the population does not rise, the situation is fine." Sun Yamin explained. If new infections rise, it means that the immunity of the population is reduced, and the new virus can enter the population and form a large number of transmissions. Therefore, if the number of cases in a country suddenly rises, it is worth our attention, but the emergence of a single "poison king" variant is not so important.
He believes that there may still be a second round of peaks, whose epidemic characteristics will be affected by the evolution of the virus. In the absence of a stronger strain, the curve of the peak of infection may be pulled from the "high and steep" of the first round to "short and long", that is, the transmission is slower, the detection is less in a single day, the impact on the medical system is small, and it slowly becomes a normal infectious disease.
Beijing News reporter Dai Xuan