Zhang Wenhong: Previous covi strains have already caused conjunctivitis, not only XBB.1.16

 Research, editing : Gan Yung Chyan, KUCINTA SETIA

News on disease control

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Get ready for the second covi infection! Zhang Wenhong's latest voice, these types of people should pay attention

Image of a Guangzhou resident leaving a pharmacy for home : Researcher's Picture

According to the latest data from China CDC, from 1 December 2022 to 13 April 2023, a total of 31,434 effective genome sequences of local cases of covid were submitted across the country, all of which were Omicron variants, covering 106 evolutionary branches. Among them, a total of 328 cases of locally focused mutant strains were monitored, including XBB.1.16, also known as "Arcturus", which has received much attention recently. This new mutant strain is regarded as the most transmissible strain, and symptoms such as conjunctivitis have been reported.

In response to recent social concerns about the new coronavirus XBB.1.16, on April 21, the National Bureau of Disease Control and Prevention stated that the level of XBB.1.16 among local cases in my country remained extremely low, and no transmission advantage was formed.

What is the XBB.1.16 variant?

XBB.1.16 is a recombinant strain of the new coronavirus Omicron, which belongs to the XBB family and is named "Arcturus" by the people. It is one of more than 600 variant strains currently prevalent in the world, and one of 137 XBB subclades. XBB.1.16 was first discovered in January 2023, and then became widespread in countries or regions such as India, the United States, Singapore, and Australia, and was officially named on 5 March 2023. The newly added mutation site on the S protein of XBB.1.16 makes it easier to spread than the parent XBB.1, and its immune escape ability is equivalent to that of XBB.1.5. In view of the growth advantage of XBB.1.16 compared with other mutant strains, the World Health Organization designated it as a monitoring mutant strain on 22 March 2023.

How common is XBB.1.16 at home and abroad?

As of April 18, at least 33 countries or regions in the world have reported 3647 cases of XBB.1.16 mutant strains, mainly from India (63.4%), the United States (10.9%) and Singapore (6.9%). Since March, the proportion of XBB.1.16 in the sequences reported in India has increased rapidly, and it has become the main epidemic strain in India. XBB.1.5 is still the main mutant strain currently prevalent in the United States, but the proportions of XBB.1.16 and XBB.1.9.1 have both increased recently. Due to the prevalence of XBB.1.16 in some Asian countries, the proportion of XBB.1.16 among the recent imported cases in China has increased. The level of XBB.1.16 among local cases in China is still very low, and no transmission advantage has been formed.

What are the features of XBB.1.16? Have the symptoms it caused changed?

Foreign studies have shown that the transmission efficiency of XBB.1.16 is slightly higher than that of the previously popular XBB.1 and XBB.1.5 mutant strains, and the immune escape ability of XBB.1.16 is comparable to that of XBB.1.5. At present, there are no reports of severe hospitalization or increased death due to XBB. In vulnerable populations, such as individuals, it is not ruled out that severe clinical manifestations may be caused by individual differences.

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Previous covi strains have already caused conjunctivitis, not only XBB.1.16

Indian and some international media reported that XBB.1.16 can cause itching and redness (conjunctivitis) in children's eyes, and "sticky eyes" without pus. However, similar eye symptoms have also been reported in cases of infection with previously circulating covi strains. If such symptoms appear in the near future, you should seek medical treatment in time and receive treatment under the guidance of a doctor.

How to avoid infection with XBB.1.16?

Survival of immunity from current vaccination or past infection can still provide some degree of immune protection to the individual. It is still recommended to wear masks when the public is in an exposed environment, a crowded place, or when they are in contact with vulnerable groups. At the same time, do a good job of self-health monitoring, especially the elderly and vulnerable groups such as those with underlying diseases should pay special attention to self-protection.

In the afternoon of 20 April 2023, at the "Infection and Immunity Summit Forum (2023)" jointly organized by the Shanghai Society of Immunology and Frontiers Journal China, Director of the National Medical Center for Infectious Diseases (Shanghai) and Director of the Department of Infectious Diseases, Huashan Hospital Affiliated to Fudan University Zhang Wenhong gave a speech entitled "Secondary Covi Infection".

He introduced that the data show that if covi mutates, a second infection will slowly appear after 6 months. Generally, the scale is small, but if the mutation of the next wave of virus effectively breaks through the human body to fight against the previous wave of virus. On the immunity barrier, the second wave will form the peak of infection. He said that to deal with the secondary infection of covid, it is necessary to pay attention to the vulnerable population, continuously monitor and warn, make good drug reserves, and respond quickly to the arrival of any mutant strains. Zhang Wenhong appealed that it is recommended that vulnerable groups be vaccinated (re-vaccinated) after 6 months, and both bivalent and monovalent vaccines are acceptable.

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Changes in the covid epidemic

Two waves of new crown epidemics have appeared in many countries and regions around the world (including Taiwan, Japan, Singapore, the United States, and the United Kingdom). Zhang Wenhong explained that there are two main cases of secondary infection: one is that the immunity of people who were infected in the first wave of the epidemic gradually weakened, and the other is that people who were not infected in the first wave of the epidemic were infected in the second wave of the epidemic. . According to monitoring data, the situation of many people infected with covid in China is the latter.

Academician of the Chinese Academy of Sciences and Professor Dong Chen from the School of Medicine of Shanghai Jiao Tong University asked after Zhang Wenhong's speech why the peaks of secondary infections in different countries are high or low. Zhang Wenhong quoted American infectious disease expert Fauci as saying, "The covid virus will find everyone. When the barrier of herd immunity is established, the covid virus will find people who have not yet established an immune barrier. Therefore, the first wave of infection control is relatively difficult. In a good country, the peak of the second wave of infections will be higher."

"Currently, the several covi variants that exist in China are mainly BA.5, BF.7, and XBB. XBB accounts for 90% of the strains prevalent in the United States, 50% in Hong Kong, and next in mainland China. It will gradually rise. It will shorten the protective time of effective neutralizing antibodies from 6 months to 4-5 months but neutralizing antibodies are still protective, and at 6 months after infection, neutralizing antibodies the protection rate is still 50%," Zhang Wenhong said.

Zhang Wenhong also said, "If no new virus variants appear after XBB, then this wave of infections may slowly go away from now on, and we will always see low-level, recurring epidemics. , if after XBB, new mutant strains continue to appear, then there will be another wave of new infections. But where is the most virulent strain, we don’t know.” Therefore, China is actively monitoring. "On the one hand, monitor whether there are new mutant strains entering, and on the other hand, monitor whether the severity of the new mutant strains is higher."

Regarding the future trend of the covid virus, Academician Dong Chen asked another question, will  covid become influenza? Zhang Wenhong said that many subtypes of influenza appear every year, with genetic recombination, more mutant strains, and greater volatility; while the subtypes of the new coronavirus are substitutional, the latter replaces the former, and there is no genetic recombination. If no special circumstances happen, it will become more and more like the existing coronavirus, which will always exist, but the sense of existence is not so strong. Whether it will become influenza in the end also depends on the characteristics of its late mutation.

In the face of secondary infection, we need to pay attention to vulnerable groups

In the face of secondary infection, we still need to pay attention to key groups. A Danish study of 7,000 people analyzed secondary infections and found that Omicron was very likely to cause secondary infections, while other strains were less likely to cause secondary infections. Women, young people, and medical workers are more susceptible to secondary infection.

Zhang Wenhong reminded that both international and domestic data show that people who were not infected in the first wave of the covid epidemic have a higher risk of infection when the second wave of infection comes. For secondary infections, people about 60 years of age and older and those who have not been vaccinated are at higher risk.

On 28 March 2023, local time, the World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) revised the roadmap for the priority use of covi vaccines. Healthy children and adolescents aged 6 months to 17 years are low-priority groups. SAGE recommends countries consider whether to vaccinate them against covid on a case-by-case basis; the elderly, young people with serious comorbidities (such as diabetes and heart disease), the immunocompromised, pregnant women and front-line health workers are high-priority groups and should be given another booster 6 or 12 months after the last dose. "If the vaccine is given again after 6 months, the antibody level will start to increase again, thereby preventing infection; after the antibody level is increased, the immune system will be easier to recall (reawakened), thereby significantly reducing the risk of infection." Zhang Wenhong said.

In addition, Zhang Wenhong said that it is still necessary to reserve antiviral small molecule drugs. At the same time, a very important measure is to establish a model of early treatment within 48 hours. Citizens can go to the nearest community health centreto test for antibodies or antigens and get corresponding drugs.

"I believe that with continuous monitoring, early warning, good drug reserves, and quick response to the arrival of any mutant strains, we will definitely be able to get ahead of the next wave of epidemics." Zhang Wenhong said.

Prior to this, many experts also expressed their views on the covid epidemic.

On 1 April 2023, Academician Zhong Nanshan emphasized at the 2023 annual meeting of the Respiratory Committee of the Cross-Strait Medical and Health Exchange Association that the vaccine to prevent re-infection of the new crown is the key. Vaccination is to "maintain the population's high immunity to covi infection".

On 13 April 2023, Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, said in a speech at the 2023 Xinjing Think Tank Spring Summit that we have learned a lot in retrospect of the covid epidemic that has just been experienced for three years. The covid epidemic has impacted not only ordinary people, but also some original cognitions of professionals, confusing basic concepts that have been understood "very comprehensively", such as "death". If the number of people infected by an outbreak is large, the death toll may be large even though the case fatality rate is low. Therefore, the scale of the epidemic plays a decisive role in the number of deaths and in judging whether the epidemic is serious. "Judging from the global epidemic data published on the World Health Organization website, the global pandemic of covid is coming to an end. "The threat of the onset and death of covid to human beings is no longer so serious," Wu Zunyou said.