As countries around the world are gradually relaxing restrictions and preparing to restart the economy, the delta strain of the new coronavirus variant virus has begun to spread rapidly around the world, leading to another increase in infection cases in many countries. Among them, some infected people have been vaccinated with the new crown vaccine before, which inevitably raises questions: Why do they still get infected after being vaccinated? Does the vaccine fail in the presence of the Delta strain?
Original title: How “poisonous” is Delta?The viral load is 1,260 times the original strain. Expert: The vaccine is playing its protective effect against severe illness. The most dangerous is the unvaccinated population
In this regard, experts explained that the phenomenon of re-infection after vaccination is called “breakthrough infection.” The emergence of this phenomenon is not surprising, nor does it mean that the protective effect of the vaccine has failed.
They pointed out that there is a general misunderstanding about the new crown vaccine, that is, “Once the vaccine is vaccinated, the new crown virus will not pose any threat to their health.” But this is not the case. Carlos del Rio de Janeiro, associate dean of the Emory University School of Medicine and an infectious disease expert, introduced,When the new crown vaccine was first developed, it was not used to prevent infection. Its purpose is always to prevent severe illness and death.
Prior to this, Shao Yiming, a researcher at the Chinese Center for Disease Control and Prevention, also expressed doubts about related issues in an interview. Our current vaccine positioning is secondary prevention, and the protection rate is for the disease, not for the infection, so some people will get the vaccine after the vaccine. May be infected.
At present, experts from various countries have recently come forward to carry out science popularization and continue to emphasize that the protective effect of the new crown vaccine against any severe infection caused by the new crown virus strain is still very strong. The people who are facing the most dangerous situation today are still the unvaccinated people.
How “poisonous” is Delta?
The viral load is 1,260 times that of the original strain
Experts say that the current major concern about the delta strain is not that it will make the disease worse, but that it is more likely to spread from person to person, leading to an increase in the number of infections and hospitalizations in unvaccinated groups.
According to a report in the journal Nature, on July 12, a group of researchers from the Guangdong Provincial Center for Disease Control and Prevention in China published a study on the medRxiv preprint platform. Follow-up analysis of 62 people infected with the Delta strain, and comparison with 63 patients infected with the new crown virus in early 2020, found that the respiratory viral load of people infected with the Delta strain was 1,260 times that of those infected with the original strain. . This shows that the self-replication speed of the Delta strain is very rapid.
In addition, people who carry the Delta strain may become infectious more quickly. Studies have pointed out that the early original strain can be detected in the human body for 6 days, while the Delta strain can be detected in only 4 days. found out.
▲On July 12, a group of researchers from the Guangdong Provincial Center for Disease Control and Prevention published a research paper on the medRxiv preprint platform. Screenshot from medRxiv
Benjamin Cowling, a professor of epidemiology and biostatistics at the University of Hong Kong, China, explained in an interview with the journal Nature that the results of this study can explain why the Delta strain is so highly infectious—high viral load. It means that more people may be infected; the short incubation period means that the infected person may begin to spread the virus earlier.
On the 27th local time, Sharon Peacock, a professor of public health and microbiology at the University of Cambridge, UK, said in an interview that the biggest risk in the world is the delta strain. The most terrifying strain of the new crown virus, it may subvert everyone’s “imagination” of the new crown epidemic.
“(People) always have an illusion that there is a panacea that can solve all the problems we encounter. The new crown virus has taught us a lesson.” Nadav Davidovich, Dean of the School of Public Health of Ben Gurion University in Israel, said with emotion road. These virologists and epidemiologists said that before obtaining more data on the spread of the delta strain, countries that have carried out extensive vaccination may also need to wear masks, maintain social distancing and other protective measures again.
“Breakthrough infections” accounted for only 0.098%
Vaccines are playing a protective effect against severe illness
According to foreign media reports on the 27th, “breakthrough infection” cases have aroused strong public concern in the United States, but the latest data shows that such cases account for a very small proportion, and most severely ill patients infected with the Delta strain are People who have not been vaccinated.
On the 26th local time, U.S. media quoted an unpublished internal document from the Centers for Disease Control and Prevention (CDC), saying that as of last week, among more than 156 million Americans who had completed vaccination, there were approximately 153,000 cases of symptoms. “Breakthrough infection” cases accounted for about 0.098% of all vaccinated persons.
In an interview, Matthew Ferrari, director of the Center for Infectious Disease Dynamics Research at Pennsylvania State University, said that the emergence of “breakthrough infection cases” was expected. He explained: “Some people who have been vaccinated will still be infected, and some will still spread (the virus). In terms of base and ratio, the more people who are vaccinated, the more cases of breakthrough infection will of course be.”
Dr. John Bronstein of Boston Children’s Hospital in the United States also pointed out: “Although word-of-mouth cases and clusters of cases may cause people to worry about vaccines, in a larger context, that is, how many people have been vaccinated, As well as the proportion of infected cases in the unvaccinated population, we can see that the vaccine is working, and the real’breakthrough (infection)’ is very rare.”
Professor Ferrari said that overall, the risk of fully vaccinated people is much lower than that of unvaccinated people, and the current level of “breakthrough infection” cases is not enough to raise concerns about the effectiveness of existing vaccines. For example, in the United States, Delta strain infection accounts for about 83% of new infections, but nearly 97% of severely ill patients are unvaccinated people.
On July 22, Yang Yi, director of the Department of Critical Care Medicine, Zhongda Hospital Affiliated to Southeast University, said in an interview with the media that most of the confirmed cases in Nanjing have been vaccinated. The condition of the confirmed cases of new coronary pneumonia this time is generally stable. The symptoms are mainly mild and common, and the symptoms are not serious. “According to our observations in Guangdong and Ruili epidemics, in general, the vaccinated cases have relatively mild symptoms, and the probability of turning into a severe case is significantly lower, and the course of the disease is relatively short. Therefore, vaccination is still It has a protective effect.” Yang Yi concluded.
In Israel, which is the first to carry out mass vaccination, according to government data, with the spread of the delta strain, the effectiveness of Pfizer vaccine in preventing symptomatic infections in the past month fell to 41%. However, Israeli health officials pointed out that although 60% of the infection cases admitted to the hospital were vaccinated people, most of them were 60 years of age or older and had underlying health problems. Therefore, Israeli experts stated that more analysis of this information is needed before reaching a final conclusion.
Red Star News reporter Xu Chang
Edit Li Binbin