Image source,Reuters
The concept of herd immunity is well-known to Chinese audiences. After the epidemic spread from China to the United Kingdom in 2020, the controversial measures taken by the United Kingdom to open the city gates to introduce the new crown virus, use natural immunity to achieve herd immunity in order to produce anti-epidemic in the whole society.
As soon as this concept was proposed, it immediately caused great controversy in the Chinese-speaking society. At that time, China was implementing grid-based home isolation management nationwide. In an interview with a BBC reporter, Chen Zhengming, a professor of epidemiology at Oxford University in the United Kingdom, pointed out that the misunderstanding of herd immunity stems from improper communication by the British government, cultural differences between the East and the West, and some misinterpreted reports from the media.
At that time, the public believed that the way to achieve herd immunity was to deliberately infect people with the virus to produce antibodies.
With the renewed awareness of the new crown epidemic and the new crown virus, all walks of life have begun to understand that the ways to achieve herd immunity are natural immunity and immunity achieved through vaccination.
At that time, when talking about herd immunity at the beginning of the epidemic, the new crown vaccine had not yet been successfully developed, and it was still in the project or the first phase of clinical trials. The public cannot see the dawn of normal life brought about by vaccination.
In the past year or so, after the rapid development of the new crown vaccine, governments of various countries can and praise the 70% coverage rate of the new crown vaccine to form an immune barrier. At that time, scientists believed that after reaching a 70% vaccination rate, herd immunity can be achieved and an immune barrier can be formed. This has also become a reference factor for governments to formulate deblocking policies.
As of September 19, 2021, according to the vaccine tracking table of Johns Hopkins University in the United States, a total of 16 countries around the world have achieved the 70% vaccination rate required by scientists to achieve herd immunity, including the United Kingdom and China , Singapore, Seychelles and other countries. Malta has the highest vaccination rate, reaching 83.09%. The vaccination rate in China is 72.25%.
Taking China as an example, reaching a 70% vaccination rate should achieve the goal of protecting high-risk groups and establishing an immune barrier, so as to restore normal social and economic life and restore contact with the world.
but it is not the truth. China is experiencing a new wave of epidemics suspected to be caused by Singaporean immigrants in China’s Fujian Province. From September 10 to September 19, Fujian Province reported a total of 335 local confirmed cases, and currently 335 hospitalized cases.
A month ago, China experienced a nationwide epidemic caused by Nanjing Lukou Airport.
Image source,Getty Images
Why did China raise the 70% pass line to over 80%?
Zhong Nanshan, a Chinese anti-epidemic expert, said after the mutated virus Delta entered China from Nanjing Lukou Airport in July, China’s vaccination rate must reach at least 83% to achieve the effect of herd immunity.
This new requirement is 13% higher than the 70% previously recognized by the scientific community. This involves the decline in the effectiveness of China’s domestic vaccines against variant viruses.
Zhong Nanshan once said that laboratory studies have shown that domestic vaccines such as Kexing have a reduced protective effect against Delta strains, but they are still “very effective.” By comparing the 153 people who were diagnosed with the Delta strain in the Guangzhou epidemic in April this year, patients who were vaccinated with Chinese-made vaccines and those who were not vaccinated, it was found that the Chinese-made inactivated vaccine had a protective effect on the Delta strain, and the overall protection rate was close to 60%. The protection rate for moderate symptoms is 70%, and the protection rate for severe patients reaches 100%. The research was published in the journal Emerging Microbes Infections.
Zhong Nanshan explained, “The effective rate of vaccines in China is about 70%, so China needs more than 80% of the entire population to be vaccinated to establish an effective herd immunity. Now, China’s vaccination rate may reach the end of this year. 80% or more.”
As of September 18, 2021, China has received approximately 2.17 billion doses of vaccines. However, China hopes to independently develop a more effective mRNA vaccine locally, so it has not approved the introduction of foreign mRNA vaccines for a long time.
Herd immunity
Hong Kong, where vaccination came from behind, as of 8 p.m. on September 18, 2021, a total of about 58.8% of the population had been vaccinated with two doses, and they had not yet reached the 70% pass line.
Most recently confirmed imported cases in Hong Kong also carry Delta mutant viruses. According to Yuan Guoyong, an authoritative expert in infectious diseases and a chair professor in the Department of Microbiology of the University of Hong Kong, the basic reproduction rate of the original virus strain is 2.5, that is, one patient can infect 2.5 people. Based on this calculation, the entire Hong Kong needs 70% inoculation rate to reach the population. immunity.
However, the basic reproduction rate of the Delta variant virus is 7. If all Hong Kong citizens are vaccinated with Kexing vaccine, an inoculation rate of 142.9% will be required for herd immunity. Even if the whole Hong Kong is vaccinated with Fubitai vaccine, the inoculation rate must reach 97.4%. Therefore, It is believed that Hong Kong cannot achieve herd immunity.
Image source,EPA
Hong Kong promotes universal vaccination
In Hong Kong, in the face of the effectiveness of vaccines and the attack of mutant viruses, the concept of herd immunity is gradually being faded. It was replaced by universal vaccination.
Nie Dequan, the director of the Hong Kong Civil Service Bureau, said that the global epidemic is still very severe, coupled with the strong spread of mutant viruses, Hong Kong must continue to work hard to increase the vaccination rate, basically all citizens who can get the vaccine should get it. This move can protect individuals and establish a strong protection net for society.
By the end of September, the Hong Kong government hopes that those who have received the first dose of the vaccine will reach 70% of the eligible population. Nie Dequan pointed out that 60% of the eligible population has received the first dose of vaccine so far. Among them, the vaccination rate for civil servants is more than 90%, and the vaccination rate for the working population aged 20 to 59 is 70%. The vaccination rate for the elderly is lower, with less than 30% of the elderly over 70 who have received the first dose of the vaccine.
The Hong Kong government is striving to increase the vaccination rate for the elderly in high-risk groups. Previously, when Hong Kong society called on young citizens to be vaccinated, saying that vaccination protects others, it has now become a call for old people to be vaccinated to protect themselves.
Those countries and regions that have obtained abundant vaccine reserves are studying and implementing strategies for intensified vaccination of the elderly in high-risk groups. It remains to be discussed whether all people need to be vaccinated with a third shot in the future.
The arrival of the booster injection means that the previously established herd immunity target is being watered down and replaced by universal vaccination.
At present, the scientific community generally believes that it is impossible for humans to eliminate the new coronavirus in a short time, which means that humans must face the fact that they coexist with the virus. However, countries such as the United Kingdom and Singapore that have reached the standard for vaccination rates and treated the new crown epidemic as a flu have “coexisted with the virus.”
In the early stages of the epidemic, Asia and some European and American countries that strictly adopted the city’s lockdown measures and the “zero clearing” policy are still working hard to increase the vaccination rate in order to achieve herd immunity like a castle in the sky. But they will eventually face “coexistence with drugs.”
