Why wasn't there a so-called second wave of the epidemic this spring?

At the beginning of the liberalization of the sealing control, there were widespread infections and various medical resources were strained, as it was liberalized years ago. So many experts predicted a second wave of infections would peak during the Chinese New Year.

The main reason is that as China's most important traditional festival, the Spring Festival will see a lot of movement of people, workers, students, tourists, traveling en masse, which will inevitably aggravate the spread of the epidemic.

But now, a week after the Spring Festival, there is no news of the epidemic spreading. People in every place are living as usual, eating and drinking, and scenic spots are crowded.

Not to mention the second wave of infection peaked, not even the second splash was seen, even the Omicron mutant strain that was the most feared strain before was nowhere to be seen.

This is actually immunologicallybased, and some foreign experience also suggests that the probability of repeat infections in the short term is relatively small.

In the body's first contact with the pathogen or vaccine, the highest efficiency of the antibody to eliminate the pathogen is the IgM antibody, the human body infected with the rapid production of with the clearance of the virus, IgM antibody to reach the peak of the virus clearance, the IgM will decline, the time required for this process in about 2 weeks, followed by the other main antibody IgG followed by the production of IgG and gradually reached the peak of the live over no longer After exposure to the same pathogen, IgG will also gradually decrease, and this process usually lasts for a month.

When the human body again the same pathogen invasion of the human body, the two antibodies will be rapidly produced, the blood concentration will also quickly reach the peak, generally 2 weeks after the time with the clearance of the pathogen, the antibody is gradually low, but at this time the concentration of IgG antibody will be in a high position to continue for a longer period of time, or even a few months of time. At this point the probability of repeat infection would be low.

In this outbreak, people who have been vaccinated are re-infected, and their antibodies will last for more than half a year, while 20-25% of people who have not been vaccinated are infected for the first time, and their antibodies will drop to a relatively low level after three months, and if they come into contact with strains of the virus that have a strong immune escape ability, they will be re-infected, but of course not everyone who has been vaccinated has produced sufficient antibodies. Of course, not everyone who has been vaccinated has produced a sufficient amount of antibodies, and this portion of the population, plus those who have not been vaccinated, may cause a small wave of outbreaks equal to about 10-20% of this wave of outbreaks in the three months following the outbreak, and this number will vary depending on the escape ability of the viral strains at the time.

Of course, China's population is so large that outbreaks don't occur at the same pace across the country, and the fluctuations that follow can vary from place to place, but the Chinese New Year's Eve period coincided with a period when everyone's antibody levels were still relatively high, and so a large-scale second wave of the outbreak didn't occur.

Simply summarize the reasons:

First, most people have already been infected.

According to statistics, after the first wave of the peak, the infection rate reached more than 80%, that is to say, 1.1 billion out of the country's 1.4 billion people were infected, and the ones who carried it through produced antibodies, and were fine in the short term.

To use the most popular phrase, there was "herd immunity".

The second is that the virus has become so virulent that even when it reaches your body, there is no reaction.

This is a very agreeable point, because our body itself carries many viruses, and the air is full of all kinds of viruses. But it's because the toxicity is so low, so low that it's no longer any different from normal air you breathe.

Professor Zhang Wenhong, director of the National Center for Infectious Disease Medicine, said the second wave could be in May.

But he also added that even if the second wave comes, it won't be a big one.

Viruses, as the oldest organisms, have been on the planet for billions of years, while the history of humans, even before they fully evolved into Homo sapiens, is less than 200,000 years.

We still know very little about it, just like the SARS epidemic that raged in our country, which came and went so violently and mysteriously that scientists still can't figure out how it disappeared.

Perhaps this new crown epidemic is the same, coming and going as it pleases.

All we can do is respond to it when it comes and send it off when it goes.