The current round of the epidemic is nearing the end of experts: early preparations should be made to deal with the impact of the second wave of the epidemic

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On January 30, the WHO issued a statement saying that although the new pandemic may be approaching a turning point, it still constitutes a “public health emergency of international concern”. The State Council press conference on the same day pointed out that the overall national epidemic has entered a low epidemic level.

The Chinese Center for Disease Control and Prevention (hereinafter referred to as “CDC”) mentioned in the “Overview of National New Coronavirus Infection Diagnosis and Surveillance Data” released on January 25 that the epidemic did not rebound significantly during the Spring Festival holiday, and no new mutant strains were found throughout the epidemic, and the current round of the epidemic in China is nearing its end.

“The main force behind the ability of the epidemic to come back down from its high point is the immunity of the population. Through this wave of the epidemic, an immune barrier was formed in the population.” A leading epidemiologist in China told China Newsweek that after the first wave of widespread infection, there will generally be no more large-scale epidemics that lead to medical run-ins. However, there should not be complete laxity at this stage. While vaccination should be stepped up, monitoring of virus mutations should also be strengthened, and the medical system should be prepared early if a trend of a resurgence of the epidemic is detected.

Kim Dong-Yan, a virologist and professor at the University of Hong Kong’s School of Biomedical Sciences, told China Newsweek that it is only a matter of time before the “public health emergencies of international concern” are over, and the WHO is expected to cancel them within a year.

Serum antibody level survey should be conducted as soon as possible

According to the “Overview of national diagnosis and monitoring data of novel coronavirus infection” released by CDC, the number of positive nucleic acid tests reported by provinces reached a peak of 6.94 million on Dec. 22, 2022, and then gradually decreased to a minimum of 15,000 on Jan. 23, 2022; the positive rate of nucleic acid tests reached a peak of 29.2 percent on Dec. 2, 2022, and then gradually decreased to 5.5 percent on Jan. 23, 2022. 5.5%. The timing of the nucleic acid test positive rate peaking and the rate of decline after peaking varied by province, with more than 70% of provinces dropping below 10%.

The published antigen testing data show that the number of positive antigen tests and positive rates in reporting provinces rose rapidly after Dec. 9, 2022, fluctuating down after reaching 337,000 and 21.3 percent, respectively, on Dec. 22, and dropping to a low of 4,773 and 4.5 percent, respectively, on Jan. 23.

“There is no exact number of infections yet, and after this wave of the epidemic has passed, the number of infections can be confirmed by conducting sero-epidemiological surveys and mathematical model estimates.” The aforementioned epidemiologist explained, “Sero-epidemiological surveys of large populations are generally led by the CDC and can now begin to be done. These results have a more important reference value in the development of subsequent epidemic prevention policies, epidemic prognosis, and confirmation of virus transmission characteristics and the proportion of serious illnesses.” The epidemiologist said.

The epidemiologist said that confirming antibody levels in the body through seroepidemiological surveys can accurately identify whether or not a person has been infected with New Crown. This involves distinguishing whether the antibodies are induced by vaccination or by natural infection, which can be analyzed with the aid of certain technical means.

In an interview with the media on January 31, Wang Quanyi, deputy director of the Beijing CDC, said that Beijing has established temporary population immune protection and that there is less risk of an epidemic occurring in the near future. Next month, Beijing will carry out a survey of the population’s serum antibody levels to comprehensively assess the new coronavirus infection.

It is understood that the survey is scheduled to be completed from February to March 2023, and a multi-stage stratified random sampling method will be used to select approximately 5,000 community populations from 16 jurisdictions and economic development zones in Beijing for questionnaire surveys and serological specimen collection. The contents of the questionnaire included basic information about the survey respondents, nucleic acid and antigen testing, onset of consultation referral, vaccination status and other information.

The aforementioned epidemiologist said that the number of infections can also be estimated with the help of data models. According to the principle of disease transmission kinetics, the reason why the epidemic will show a rise and fall is related to the number of infected people and the level of herd immunity formed after infection, and the whole process can be estimated with a model, and a good model simulates the results very close to the real situation.

Since December last year, several provinces in the country had counted regional infection rates in the form of questionnaires. “Questionnaire survey is also a method, but this way there is no way to get data on asymptomatic infected people and infected people with very mild symptoms.” The aforementioned epidemiologist said.

Jin Dongyan told China Newsweek that after the end of the pandemic, the new crown did not disappear, but became an endemic epidemic, and people still need to “deal” with it all year round. Every year, people will still be infected, and there will be people who develop serious illnesses or even die after infection, but the proportion will be much smaller compared to this round. “Now it is necessary to find out the real data of infection in the country, so that the next step can have a clearer response plan.” Jin Dongyan said.

Seize the “window period” and speed up the stockpile of oral antiviral drugs

A number of experts told China Newsweek that there is definitely a short-term social herd immunity and that the epidemic has reached its end. From the experience of other countries around the world, there must be a second and third wave of the epidemic to follow, but it will not be as fierce as this one.

New crown vaccination

“The very large majority of people at this stage have experienced the infection, and with the relatively high vaccination rate itself, the double effect creates a very high percentage of immunized people.” said the aforementioned epidemiologist.

Lu Mengji, a German-Chinese virologist and professor at the Institute of Virus Research at the University of Essen Medical School, told China Newsweek that in Germany, the peak of infection is stretched out, and the immune barrier is not formed simultaneously after infection; everyone is not universally susceptible all at once, and the immune barrier becomes more and more solid with repeated infections. In contrast, mass infections in China quickly cross the peak, and there is a strong synchronization of the immunity formed in the population. If we do not seize this window period, there will be the possibility of re-emerging a certain scale of infection and “repeated over-peak”.

Lu Mengji expects that from late March this year, with the decline of the population immunity, the risk of infection will increase, and in May and June, the epidemic will change significantly, and then may face a second wave of impact. But whether the second wave of the epidemic will occur in March or May or June depends on whether a new strain with a very high impact will emerge.

An Omicron subvariant called CH.1.1 has been reported to have emerged in the United States. It is an offshoot of the mainstream strain BA.2.75, which some experts have named “Orthrus”, meaning “two-headed dog” in Greek mythology. As of Jan. 30, 2023, no indigenous cases of CH.1.1 or its sub-branches have been detected in the country.

“Now that the evolution of the new coronavirus has stabilized, there is no need to worry too much about the emergence of new mutant strains, but they need to be monitored regularly to keep track of the dynamics of the mutant strains. In fact, CH.1.1 is not recent, it was first discovered on January 9, 2022, and has also previously accounted for 1/3 of epidemic strains in the UK, when it was also not found to spread faster or be more pathogenic.” Jin Dongyan said.

The CDC WeChat public number recently issued an article to explain that, at present, no enhanced pathogenicity of the CH.1.1 variant strain has been seen, and further attention is still needed. The new strain of CH.1.1 will not cause a large local epidemic in the short term. Vulnerable and uninfected populations still need to strengthen personal protection.

Previously, Gao Fu, academician of the Chinese Academy of Sciences and former director of CDC, said in an exclusive interview with China Newsweek that if the XBB mutant strain eventually becomes prevalent in the country in March and April, from the vaccine and immunization point of view, people may be infected again. after XBB enters the country, if the current epidemic BA.5 and BF.7 can provide some cross-protection against XBB, it is also possible that XBB will not become prevalent, not This possibility is not ruled out.

For the country, there is still a “window period” before the second wave of the epidemic.

“You can’t just wait for a second wave to happen without intervention.” If the second wave of the epidemic is also short, many young people will be able to get through it with a stronger immune system, but this is not the case for many elderly people, Lu said. Many of the elderly who have been infected are now recovering physically, and the consequences of another infection for many people with poor health could be very serious. Some of the people at risk with immune deficiencies who did not become infected during this phase may also face the next wave of the outbreak.

“To better cope with the next wave of the epidemic, it is important to seize this window period before the next wave of the epidemic comes and speed up vaccination and the stockpiling of antiviral oral drugs.” Jin Dongyan said. In his opinion, if the vaccine itself cannot target the new strain, the effectiveness of vaccination will also be weakened. In addition, he suggested that the approval and introduction of mRNA vaccines should also be accelerated along with enhanced vaccination in the future.

“In Hong Kong, people over 50 years old or with weak immunity can be vaccinated three months after Yang over, especially high-risk groups and elderly people with underlying diseases.” Jin Dongyan suggested that an equitable drug distribution mechanism should be established to ensure that vulnerable people can be given medication in a timely manner once they are infected.

The aforementioned epidemiologist said that the domestic vaccine strategy for long-term prevention of the new crown is now inconclusive.

How often do I need to be revaccinated? The epidemiologist said that if the infection is to be prevented, the frequency of repeat vaccination should be high, about 6 months for a dose, and as much as possible for a vaccine matching the prevalent strain; if the purpose is to prevent serious illness, the cycle of revaccination can be stretched longer, a year or even two years, because the protection period of the vaccine is at least one year. However, the former is less feasible, and only a small number of vulnerable people need such frequent vaccination.

A public health expert told China Newsweek that monitoring of virus variants and preparations for medical treatment of the elderly population, especially the unvaccinated elderly population, should be done during the window period.

Jin Dongyan said the “tsunami” of the epidemic experienced by the country has gained time to deal with the next wave of the epidemic, during which time “three lines of defense” should be firmly established, namely vaccination, stockpiling of antiviral drugs for the new crown, and building a firm medical system to rationalize people’s understanding of the new crown. We should not be afraid or numb, but treat it correctly to minimize the damage in all aspects.