"The Lancet": Wuhan long-term new crown serum flow adjustment results announced! Among the subjects, 6.9% were antibody-positive, 82% were asymptomatic infections, and the neutralizing antibody-positive rate was 40% and maintained for at least 9 months

The results of a long-term seroepidemiological follow-up survey conducted by the Wuhan Centers for Disease Control and the Chinese Academy of Medical Sciences on more than 3,500 families and more than 9,500 subjects in Wuhan were published in The Lancet on March 19 [1], providing new evidence for understanding the changes in immune status in the new crown epidemic.

The first test of this study was carried out in April 2020.
Among the subjects, 532 people tested positive for anti-SARS-CoV-2 pan-immunoglobulin (Pan-Ig), and the baseline antibody positive rate was 6.
9%, which was higher than in previous studies.
The reported positive rate of Wuhan antibody (3.
2-3.
8%) is higher, and 437 of them have asymptomatic infection (82.
1%) [2].

Among the subjects with positive baseline antibodies, 212 (39.
8%) had neutralizing antibodies against the virus.
During the two follow-up visits to the subjects in June and October to December 2020, the neutralizing antibodies The positive rates were 44.
6% and 41.
2% respectively, which remained roughly stable, suggesting that the neutralizing antibody can exist stably for at least 9 months.

However, according to research data, the positive rate of neutralizing antibodies in the population of Wuhan is only about 2.
8%.
This reflects the effect of effective prevention and control measures to block further transmission in the early stage of the Wuhan epidemic.
On the other hand, it also shows that it is necessary to prevent When a large-scale epidemic occurs again, vaccination of the new crown vaccine is essential.

Of course, the immune escape mutation of the new crown virus is also a difficult problem now (Image source: Pixabay) After the outbreak of the new crown virus, scientific research teams around the world are conducting sero-epidemiological studies to judge the actual spread of the epidemic based on the positive rate of antibodies.
To provide a reference for prevention and control in the future.

However, the global epidemic has been more than a year, and there is only one outbreak like Wuhan, and there are really few places that have not made a comeback.

Therefore, if you want to conduct long-term follow-up of antibody changes in the population after a single outbreak, Wuhan has become a very ideal research site.

The research team used a multi-stage cluster random sampling method to select subjects from all 13 districts in Wuhan to conduct on-site questionnaire surveys, throat swabs and serum antibody tests.

A total of 532 subjects from 391 families tested positive for antibodies.
The corrected Pan-Ig positive rate, that is, the antibody positive rate was 6.
92%, of which Qiaokou District and Jiangan District had the highest positive rates, 13.
08% respectively.
And 11.
12%, 82.
1% of the test-positive subjects did not report fever and respiratory tract new coronary-related symptoms.

The antibody positive rate of various districts in Wuhan, 4 districts exceed the average level of the city.
If calculated based on the 9 million population in the city during the lockdown period of Wuhan, then the antibody positive rate of 6.
92% corresponds to the actual number of infected people of approximately 623,000, which is Wuhan Reported about 12 times the number of confirmed cases, which is related to many people being asymptomatic after infection.
The paper also pointed out that the subjects’ descriptions of whether there are symptoms are more reliable.

Previously, there were basically similar conclusions in antibody flow studies around the world.
For example, in the flow study conducted in Los Angeles, the United States last April, the antibody positive rate was 4.
65%, so the calculated number of infections was 367,000, according to the statistics of the local health department at the time.
More than 40 times the number of confirmed cases (8430 cases) [3].

Of the 532 subjects who tested positive for Pan-Ig at baseline, 69 (13%) were positive for IgM antibodies, 84 (15.
8%) were positive for IgA antibodies, and 212 were positive for neutralizing antibodies and were asymptomatic.
The levels of neutralizing antibodies in infected patients are lower than those in confirmed and symptomatic infections.

A total of 335 Pan-Ig-positive subjects completed all three follow-ups.
During the follow-up period of the study, the antibody levels of neutralizing antibody-positive subjects did not significantly decrease.
This finding is also consistent with the protective effect of the new crown vaccine.
Significant.

The changes in antibody levels during baseline testing and two follow-up visits.
In the editorial published by The Lancet at the same time, two experts from the University of Melbourne stated that the results of this “milestone” study showed that “in the detection, tracking and treatment resources Far less than the current situation, the Chinese public health system has adopted rapid, effective and extraordinary prevention and control measures to successfully control the outbreak of the new crown epidemic in Wuhan.
"
The editorial also pointed out that effective prevention and control measures have also lowered the rate of herd immunity brought about by the natural spread of the epidemic.
The new crown vaccine is still very important for the global fight against the epidemic.

But after watching Singularity Cake for so long, how can a country that allows the spread of the epidemic to achieve herd immunity? The combination of prevention and control + vaccine must have a smaller price.

Reference materials; 1.
He Z, Ren L, Yang J, et al.
Seroprevalence and humoral immune durability of anti-SARS-CoV-2 antibodies in Wuhan, China: a longitudinal, population-level, cross-sectional study [J] .
The Lancet, 2021, 397(10279): 1075-1084.
2.
Xu X, Sun J, Nie S, et al.
Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in China[J].
Nature Medicine, 2020 , 26(8): 1193-1195.
3.
Sood N, Simon P, Ebner P, et al.
Seroprevalence of SARS-CoV-2–specific antibodies among adults in Los Angeles County, California, on April 10-11, 2020[J ].
JAMA, 2020, 323(23): 2425-2427.
Source of head picture: Pixabay Author of this article | Tan Shuo