The overall protection of Pfizer vaccine (BNT vaccine) against the new coronavirus is 95%, which is the highest among all current new coronavirus vaccines. However, the latest statistics from the Israeli Ministry of Health show that the overall protection of Pfizer vaccine from June to July was only 39%. According to expert analysis, there may be two reasons.
Israel implemented Pfizer’s vaccination plan in December last year, while implementing strict lockdown measures, and then the epidemic has slowed down. When the national vaccination rate exceeded half, the authorities gradually lifted most of the epidemic prevention restrictions. However, in June, the epidemic rose again, and many of the infected people had already received two doses of the vaccine.
In January, Israel conducted a large-scale study of Pfizer vaccines, and published the results of the study in The Lancet in May. This study is based on data from the end of January to the beginning of April, showing that the overall protection of Pfizer vaccine is 95%.
However, in July, the latest statistics from the Israeli Ministry of Health found that the protective power of Pfizer vaccines has dropped significantly. From June to July, the overall protective power was only 39%.
This new study targeted 1.8 million people and observed the following changes from June 20th to July 17th:
1. The vaccine still has the effect of preventing hospitalization and severe illness
Data from January to April shows that the hospital protection of Pfizer vaccine is 97%, and the protection of severe illness is 98%.
As of June to July, the hospitalization protection is still 88%, and the critical illness protection is 91%. The Pfizer vaccine can still effectively prevent the infection of the Delta variant virus, resulting in hospitalization and severe illness.
2. The protection against symptomatic infections is significantly reduced
After 6 months, the protection against symptomatic infection dropped to 40%.
3. The overall protection of the vaccine decreases over time
The study found that people who completed two doses of Pfizer vaccine in January had only 16% overall protection remaining from June to July. The number of people vaccinated in February dropped to 44%; 67% of people vaccinated in March; and 75% of people vaccinated in April. The overall protection power of 39% is based on this.
4. The rate of breakthrough infections at different ages has increased:From adolescents to the elderly, the situation is the same, that is, the longer the vaccine is given, the higher the incidence of breakthrough infections.
Among them, the 16-59-year-old group is more serious. In January, the second dose of vaccine was given, and the breakthrough infection rate was the highest. Among 100,000 people, 74 people were infected. Groups aged 60 and above also showed a similar trend.
2 Reasons for decreased protection, Delta variant virus is one of them
The Israeli study revealed an obvious message: As time goes by, the protective power of the vaccine on the population is also fading. The earlier the population vaccinates the second dose, the more severe the decline in the protective power of the vaccine.
This study also has two limitations. One is that the data collection time is short, and there may be deviations, which need to be continuously corrected and fine-tuned in conjunction with updated data; the second is that the sample size is 6.5 million compared with the number of researchers published in the journal The Lancet in May. Small, “but more than 1 million people are not a lot,” said Dr. Dong Yuhong, a European virology and infectious disease expert and chief scientist of a biotechnology company.
Dong Yuhong believes that there are two reasons for the sharp decline in Pfizer’s vaccine protection:
1. Antibodies fade over time
The antibodies that people get from vaccinations are metabolized by the body and fade away over time.
The best time of protection provided by the vaccine may be within 5 months after the second dose. Beyond this time, the effectiveness will gradually decrease. Therefore, governments and scientists of various countries are discussing whether to give a third booster shot. However, with the increase in the number of vaccination, the adverse reactions should be paid more attention.
2. Delta variant virus is too transmittable
After the Delta variant infects the human body, the viral load in the body is high, the transmission speed is faster, the transmission power is stronger, and it is easier to break through the defense line of human immunity.
A collaborative study between the University of Oxford and CDC in Guangdong, China shows that the viral load of the Delta variant in the human respiratory tract is 1,000 times that of the original virus.
Singapore, which also experienced the spread of the Delta variant, also experienced a similar situation to Israel. According to data released by the Singapore government on July 22, of the 1,096 local infections in the past 28 days, about 44% were those who had received two doses of the vaccine, 30% were those who had received one dose, and 25% were those who had not been vaccinated. . It’s just that these vaccinated people did not become seriously ill after contracting the disease.
The situation in Israel and Singapore is similar: both vaccine coverage rates are high, and Singapore is mainly vaccinated with Pfizer and Modena vaccines.
Rochelle Walensky, director of the US CDC, called the Delta variant virus: “one of the most infectious respiratory viruses known to scientists.”
The Delta variant virus has also become a major epidemic strain in the United States. With the rapid increase in the number of confirmed cases, the United States is considering updating the epidemic prevention guidelines, restoring the mask order, and recommending those who have been fully vaccinated to start wearing masks indoors again. Valensky bluntly stated at the press conference that the biggest concern is that after the Delta variant, “new variants may appear next and escape the protection of the vaccine.”
In a troubled world, if you have a healthy mind, just lookHealth 1+1!
· What is the reason why nearly one-third of the British died of Indian variants received 2 doses of vaccine
· The 3 dangers of Delta variants!See new symptoms and vaccine protection at a time
·[Replay]Pfizer vaccine’s latest protection is less than 50%?
Editor in charge: Li Qingfeng
.