The wave of coronavirus infections predicted by experts has been delayed
Since entering the winter of 2023, experts from all walks of life have predicted several times that there will be a new wave of new coronavirus infections in the mainland at time nodes such as "entering winter" and "around New Year's Day".
In this regard, I have written an article entitled "Will there be a small spike of new coronavirus infections in the mainland in the near future?" What is more worthy of vigilance is the flu Experts predict that a wave of infections may be set off around New Year's Day? Does it have anything to do with the mainland? There will be no wave of new coronavirus infections in the mainland in the near future It is predicted that there will be no new coronavirus infections in the mainland before the Spring Festival, and a new round of epidemics will probably occur after the Spring Festival, especially after the start of school in the spring.
As a result, the new crown epidemic expected by experts has not arrived for a long time, and the spread of the new crown virus on the mainland has been at the lowest level since the pandemic throughout the winter, and the positive rate of the new crown virus in influenza-like cases in sentinel hospitals has been reduced to less than 1% at one point.
The positive rate of influenza-like cases has risen, and a new round of new crown infections is coming?
However, as I predict, with the spread of the JN.1 variant in the mainland and the movement and gathering of large-scale crowds during the Spring Festival, the mainland will usher in a new round of small-scale new coronavirus infections after the Spring Festival, especially after the spring school year.
On February 6, 2024, the CDC released the "National Novel Coronavirus Infection Epidemic Situation (January)", and on February 15, 2024, the National Influenza Center released the "Influenza Surveillance Weekly Report (2024 Week 6)" The data show preliminary confirmation of my prediction.
According to the National Situation of Novel Coronavirus Infection, since the beginning of 2024, the proportion of influenza-like cases in outpatient (emergency) visits (ILI%) in sentinel hospitals across the country has continued to decline, which mainly reflects the easing trend of the influenza epidemic.
This is also illustrated by the continued decline in the positivity rate of influenza-like cases in sentinel hospitals.
However, at the same time, there has been a significant rebound in the COVID-1 positivity rate of influenza-like cases, increasing from 0.9% in the first week of 2024 (the lowest level after liberalization) to 2.0% in the fourth week.
The spread of the JN.1 variant is the number one driver
Importantly, the "Virus Mutation Surveillance of Local Cases" shows that in the first month of 2024, the transmission spectrum of the new coronavirus variant monitored in the mainland has changed significantly, and the proportion of XBB lineage represented by EG.5 and its subclades has decreased significantly, replaced by the rapid spread of the new variant JN.1, which has surpassed the EG.5 line by the fourth week and has become the absolute dominant strain in the mainland.
The positive rate of influenza-like cases increased, and JN.1 quickly became the dominant strain, indicating that the new wave of infection of "small lotus is showing sharp corners" is driven by JN.1.
A new round of the pandemic may already be on the way
Since the "National Novel Coronavirus Infection Epidemic Situation" is a monthly report, it can only reflect the spread of the new coronavirus in January and cannot provide updated epidemic information.
However, the Weekly Influenza Surveillance Report, published by the National Influenza Center, is a weekly report, and the latest report, the sixth week of 2024, provides information on the influenza epidemic as of February 11, 2024.
We know that, like most countries in the world, the mainland has "integrated" the surveillance of the new crown epidemic with the monitoring of the epidemic of influenza, and the data on the new crown epidemic actually comes from the influenza surveillance network, and the detection of influenza virus in sentinel hospitals has been added to the detection of influenza virus in sentinel hospitals.
The same population was monitored, i.e. influenza-like cases (fever over 38°C with cough or sore throat) presented to sentinel hospitals during the period.
According to the latest issue of the Weekly Influenza Surveillance Report, the positive rate of influenza virus in influenza-like cases in sentinel hospitals continues to decline.
In the southern provinces, it dropped from 32.4% in the fifth week to 31.7% in the sixth week, in the north from 26.3% to 22.3%, and the national average from 29.4% to 26.9%.
However, during the same period, the ILI% of sentinel hospitals rebounded significantly, with the southern provinces rising sharply to 7.9% from 6.3% in the previous week.
The northern provinces also rose from 5.1 per cent to 5.7 per cent.
This segregation of influenza-like cases as a percentage of total outpatient and emergency cases (ILI%) in sentinel hospitals and the influenza virus positivity rate of influenza cases suggests that influenza-like cases presented to sentinel hospitals are more "adulterated" with viruses other than influenza viruses.
According to the characteristics of respiratory virus epidemics, traditional coronaviruses, parainfluenza viruses and respiratory syncytial viruses tend to decline after spring, and the transmission of influenza and rhinovirus usually occurs, and adenovirus will continue to maintain a certain epidemic level.
However, due to the record epidemic of influenza A H1N1pdm09 and H3N2 subtypes just experienced in spring and winter, the population still maintains a high level of herd immunity and is unlikely to form a large-scale spring influenza epidemic.
This means that sentinel hospitals have recently seen an increase in the proportion of ILI%, mainly due to the "warping" epidemic of rhinovirus in the spring, and the "mixing" of new members in addition to the old viruses mentioned above.
This new addition can hardly be considered the most contagious and at the same time the mildest COVID JN.1 to date.
In other words, despite the difference in timeliness, the "National Novel Coronavirus Infection Epidemic Situation" only shows that a new round of new crown epidemic "dragon rises", and the latest influenza surveillance report indicates that the new crown epidemic is already on the way.
The "blessing" of the Spring Festival and the beginning of spring school
As I said earlier, the pandemic has not shown significant seasonality, and the pandemic is largely event-driven.
The main drivers include the emergence of new variants that are more contagious, the waning of population immunity over time, and the movement and clustering of people due to holidays.
New and easy to see, the first driving factor of the new round of new crown epidemic that has just "risen" is naturally the spread of JN.1 in the mainland.
Next, the Spring Festival nationwide tandem and the help of the student group after the start of the spring semester will further accelerate the spread of JN.1, which will inevitably drive a new wave of new coronavirus infections.
In addition, although there may be some rebound of the flu in the spring, it is necessarily lower than in normal years. This also played a role in the "cage for birds" effect of the spring coronavirus epidemic - the principle is the "virus interference" that I have already introduced.