In this regard, Professor Meng Guoyu from Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine said in an interview that once every three months is not enough, but once every six months is possible.

As the overwhelming first wave passes its peak, people’s attention is increasingly focused on when the second wave of the epidemic will arrive.

In this regard, Professor Meng Guoyu of Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine said in an interview that once every three months is not enough,

once every six months is possible. The peak of the second wave may be in May and June, and will be about 25%-50% of the current level.

We don’t know what the basis is for this professor to make the above judgment in such a positive tone.

If we talk about epidemiology and theory, how should we deduce and judge?

An infectious disease is in the pandemic stage. The main basis for judging its epidemic situation is still the source of infection, the route of transmission and the susceptible persons.

Source of infection: Super Mario

From the perspective of the Omicron evolutionary tree, BA.5.2 and BF.7 are already the top sublineages except the BQ.1 family.

If BQ.1 and BQ.1.1, which have been widely spread in Europe and the United States, are introduced into my country and become the main force driving the second wave of epidemics, it is expected that the second wave of epidemics in my country will arrive later and be smaller in scale.

This is because BQ.1 and BQ.1.1 are the same descendants of BA.5 as our popular BA.5.2 and BF.7. They are closely related by blood and have higher cross immunity.

However, now that XBB has suddenly emerged, the possibility that BQ.1 and BQ.1.1 will become the second wave of dominant strains in my country no longer exists.

Regardless of theory or the law of the transformation of new coronavirus variants in the United States, XBB, especially XBB.1.5, has a transmission advantage that far exceeds that of BQ.1 and BQ.1.1. Only a few weeks after its emergence in the United States, it has pushed BQ.1 and BQ.1.1 out of its dominance with a rapid doubling rate every week, and has become the only dominant variant in the United States.

As my country completely relaxed border quarantine on January 8, 2023, XBB.1.5 was rapidly introduced into our country and spread widely, which is irreversible.

There is a high probability that BQ.1 and BQ.1.1 will have little chance of expansion in my country and will be directly suppressed by XBB.1.5.

If this assumption is true, the second wave of popularity in my country must be Super Mario XBB.1.5.

It is known that XBB is the recombination of two sub-variants of BA.2.10.1 and BA.2.75 under the BA.2 lineage. XBB.1.5 is the latest sub-line of XBB and has stronger transmissibility than its ancestor XBB.

Although, from the perspective of the Omicron evolutionary tree, the XBB.1.5 and BA.5 families are both descendants of BA.2. However, the blood relationship between BA.2 and BA.5 is much further than within the BA.5 family.

This also means that the potential cross-immunity between XBB.1.5 and the first wave of popular BA.5 family members in my country is much smaller.

In this way, the second wave led by XBB.1.5 "should" come earlier than expected and be larger in scale.

Communication channel: Our country is the flattest country, and we don’t need one.

I said that after the relaxation of control this time, our country is already one of the flattest countries in the world.

Some netizens strongly disagreed, insisting that our country is the only country that lies flattest and does not need anything.

In short, no matter it is one or the only one, no matter who comes in to play the leading role, the communication in our country will not encounter any decent "resistance", and the communication channel must be the most common way.

Therefore, we do not need to have any "worry" about the second factor driving the second wave, the transmission route.

Accumulation of susceptible persons

The susceptibility and quantity accumulation of susceptible persons are the core factors affecting the epidemic of infectious diseases.

Some infectious diseases that pose a major hazard to human health, such as smallpox, measles, chickenpox, tuberculosis, etc., can be completely or partially controlled because we rely almost exclusively on the immune barrier established by universal vaccination, allowing the entire or most of the population to become immune to specific infectious diseases, rather than susceptible.

and The reason for the new crown is that scientists have predicted from the beginning of the outbreak that it will not be completely controllable and will turn into an endemic epidemic after the pandemic.

The main basis for scientists to make this judgment is that several other human coronaviruses have established a "herd immunity" barrier with a certain threshold through widespread natural infection and/or vaccination. There are two main reasons:

First, coronavirus continues to mutate, and new variants will continue to acquire stronger immune evasion capabilities to avoid the protective immunity induced by previous infection or vaccination to prevent infection;

Second, whether it is natural infection or vaccination, the immunity that prevents infection will decline rapidly, and will be completely ineffective in as little as 2 to 3 months, and can last for half a year, or even longer.

This means that even if does not take into account the immune escape caused by virus mutation , driven only by immune decline, whether the population obtains immunity through natural infection or vaccination, it will become susceptible again within the next 2 or 3 months at the fastest, thus rapidly expanding the size of the susceptible population.

In other words, given the super source of infection and unhindered transmission routes, just from the perspective of immune decline, the new coronavirus "should" have the opportunity to have another wave every 2 or 3 months, and this rhythm will continue to cycle. The immune evasion brought about by the

virus mutation is just a "boost", and its influence on the scale of the epidemic is more significant than the influence of the epidemic rhythm.

I advanced the second wave of popularity to February

In France and South Korea, which I have given many examples, the intervals between the first two waves are 2.5 and 5 months respectively, and the size of the second wave is about one-third of the first wave;

In Germany, the interval is 5 months, and the scale is one-third;

Italy and the United Kingdom, both are 2 months. and one-third;

Belgium , 3 months and one-fifth;

Austria, 3 months and one-quarter;

Australia, 3 months and one-half;

Singapore (although its population is less than 10 million, it has gone out of the typical multi-wave trend and has always been a respected benchmark country for epidemic prevention, so it is also included), 5 months and one-half.

Judging from the general trend of the above-mentioned countries with large populations that have emerged from multiple waves of Omicron epidemics, the second wave is roughly between 2 and 5 months away from the first wave, and the scale is about one-fifth to one-half of the second wave.

Considering that the first wave in my country has basically passed its peak, and will face the impact of the Spring Festival "Big Series" and Super Mario XBB.1.5, it is reasonable to expect that the second wave will most likely debut in February, with the scale being about one-quarter to one-third of the previous wave.