Mass-Testing Qingdao, China Testing Nine Million Case After Confirmed Six Cases ! Is it hardworking and brave ? No, It’s science
The British city of Liverpool just concluded a large-scale coronavirus testing project on November 20, which is the first time that the UK has conducted a large-scale testing in a city.
Liverpool, the region with the highest COVID-19 death rate in England, is about 2 times the average per million people in England, so it was selected as a pilot.
This pilot project is regarded as the hope of the whole UK and will be promoted throughout England after January 2021.
So how many people have been checked?
The original goal was to test Liverpool’s total population of 500,000 within two weeks.
But at the end of two weeks, the target was less than half achieved, with about 200,000 people tested, about 2,000 positive and 600 asymptomatic infections.
Those Chinese tests that shocked the world
China was one of the first countries to carry out large-scale testing. I still remember that in May, Wuhan measured 9.9 million people in 18 days, and the daily detection capacity could reach 1 million, which means that the daily measurement was five times that of Liverpool’s two weeks.
In October, Qingdao completed more than 10 million tests in the city in five days.
Qingdao set a world record and shocked the foreign media.
Why China’s coronavirus department testing is so fast, in fact, the real secret lies in “mixed mining testing”.
Wuhan used “mixed mining detection” for the first time, which is simply to test samples in groups. If a group results positive, everyone in this group will be notified to isolate immediately and conduct a “single-take test” on each person to find the “source” of the virus in this group of samples.
At that time, Wuhan divided five samples into groups to detect, while Qingdao divided 10 samples into groups, and then flew at a speed.
After all, the coronavirus spreads too fast. The test is racing against the virus and fighting a blitzkrieg.” Group testing is fast and cost-saving. In fact, it has been adopted by China, India, Germany and the United States. However, China’s execution is amazing, and for other reasons (see below), the effect is particularly amazing.
Scientific highlights in group detection
“Group detection” is quite brain-burning when digging deep, and innovations from the mathematical field are endless. The authoritative scientific journal Nature has previously introduced four methods.
Method 1: In fact, it is very similar to China’s “10 in 1” and “5 in 1”, which is also the most direct and easy to operate method.
This method was first proposed by Harvard University economist Robert Dorfman in the 1940s, when it was used to detect how many World War II soldiers carried syphilis. Later, it was also often used to screen how many people in asymptomatic people carried chlamydia and gonorrhea viruses. The Red Cross will also use this method to screen blood donors for hepatitis B, HIV, etc.
Method 2: Similar to “method 1”, they are all “non-overlapping groups”, the difference is that it is grouped after grouping.
The advantage of this scheme is that the number of times is reduced – “Method 1” needs to be checked (3+9 = 122 times, and “Method 2″ only needs to be checked (3+3+3=”9”) 9 times.
But its disadvantage is that there are too many rounds.
If the results of each round of testing need to wait for a long time, it will lead to a long delay. And it is also difficult to operate to ask someone back to test three times.
The first two methods are “non-overlapping groups”, while starting from “method 3”, it is a more subtle “overlapping group”, that is to say, the same sample can be divided into different groups, and there is an overlap between groups and groups.
Method 3: Upgrade dimension.
Nine samples, measured three times by “column” and three times by “row” group (see the arrow of the second round). If the “row” or “column” is positive, then one sample that appears in both groups can be judged to be positive (red).
Two-dimensional can also be upgraded to multi-dimensional, which is more effective on scale. It’s just that this method may be a little complicated in practice, especially when there is more than one positive case in a group, it is necessary to rely on algorithms to calculate which is a positive sample. Scientists in Rwanda are exploring this strategy.
Method 4: Use one round to do it.
The first few methods need to be divided into several rounds, and the second round of the test must wait for the results of the first round, and the third round of the test must wait for the results of the second round. The more rounds, the longer you wait, the more time is delayed. Faster than viruses, scientists then study whether the rounds can be compressed to the limit?
Computer science at the Indian Institute of Technology uses Kirkman triples in mathematics to complete the “one round of completion”. The example shown below is that if you test nine people, you only need to test six times to find the only positive.
But this method is the same as “method 3”. As long as the amount of data is large, grouping and recognition will exceed people’s computing power. Let the front-line inspectors operate in this way, it is estimated that people will faint.
So the matter of “calculation” should be handed over to the computer. Write the right algorithm and develop the right program, and the power of “method 4” will explode exponentially. At present, Indian scientists have successfully identified 5 positives out of 320 samples with only 48 tests.
In addition to the inspiration of mathematics, group detection also attracts the attention of scientists in the field of artificial intelligence. The medical community is also exploring how many samples are divided into groups. Doesn’t it cause the virus to be overdilution and lead to failure to test positive?
Therefore, “it is appropriate to put a group of samples” is not a matter that can be determined by slapping the forehead. Behind it is science.
China’s method, “Scheme 1”, is the easiest to operate and easy to use, especially suitable for the “blitzkrieg” that is immediately made. But breaking through the threshold and breaking the limit always depends on science. And science takes time. It may not be reflected in execution in the short term, but this is a long-distance race. The moment of upgrading has not yet arrived, so we can’t be arrogant.
Why China Health is powerful ?
Why China Health is powerful ? In July, an article written by American researchers was published on the “Dialogue” website, discussing the limitations of “group testing”.
The article said that if 9% of people tested positive in a city like Los Angeles, “group testing” can only reduce the cost and time by 50%. If Montana, where only 0.1% of the population is infected, the cost of testing can be reduced by nearly 90%.
The reason is very simple. The more infected people, the more positive the first round will be tested in groups, and the more people will need to be tested for the second round. What are the advantages of group inspection?
Liverpool in the UK tested only 200,000 in two weeks. Professor Kallum Sempel, an infectious disease expert at the University of Liverpool, explained:
Professor Kalum Semple, consultant of the British Scientific Advisory Group on Emergencies (SAGE) and infectious disease expert at the University of Liverpool, was interviewed by the reporter of the main station.
Therefore, China’s “group detection” strategy may not be copied, or it may not have such amazing effects as China’s use, because each has different “bases”.
China is decisive in fighting the epidemic, often testing the whole city with only a few local transmissions. In the first round, the group was found to be negative, which was quickly screened off, so the detection was very fast. This forms a kind of “positive feedback” – less infection, so fast detection; fast detection blocking the spread of the virus, so less infection.
Professor Peter O’Pinshuo, president of the British Immunology Society, said in an exclusive interview with the station, “China’s testing method is admirable, and I hope we can follow suit in Britain.”
This is not self-humility, this is a judgment. At this stage, this method may not be the most suitable for them.
For us ordinary Chinese, when enjoying the praise and highlights from the world, we should also know it and why. Always explaining with diligence and courage is not conducive to becoming smarter.