Herd immunity may require 80% of the population to complete the vaccination!

▎The protective effect of the new crown vaccine edited by WuXi AppTec's content team can be reflected in two major aspects, including preventing infection and preventing the development of the disease after infection (preventing symptoms).

In the clinical trials of the new coronavirus vaccine, most of the attention is paid to the vaccine's protective effect on the symptomatic infection-the new coronavirus disease (COVID-19).

With the release of more real-world research data and reports of a few cases of infection after vaccination, the vaccine's preventive effect on overall infection (with or without symptoms) has also become more concerned.

However, most of the existing data in this area comes from subgroup analysis with relatively small sample sizes in the trial, or analysis of alternative indicators of asymptomatic infection, rather than direct detection.

Recently, "The Lancet" published the results of a major study of SIREN.
The large-scale, frequent nucleic acid tests for asymptomatic groups among medical workers across the country provided an important reference for the true effect of vaccines in preventing infection.

The "Lancet" review article in the same period pointed out that, combined with the findings of this study, achieving herd immunity through vaccination will require the entire population to have a high vaccination rate.

Screenshot source: Preliminary data on infection prevention by The Lancet new crown vaccine.
The SIREN research team pointed out in the paper that there is currently a lack of routine nucleic acid tests on asymptomatic people to detect asymptomatic infections and analyze the data on vaccine prevention infections.
.

Previously, two real-world studies from Israel provided us with preliminary data: The data of 9109 medical workers in Sheba Medical Center published by The Lancet showed that the first dose of BNT162b2 vaccine (co-developed by Pfizer/BioNTech) was 15th -28 days, the risk of infection is reduced by 75%.

The detection mechanism used in this study is to implement daily symptom reporting in the hospital combined with the same-day testing, so that people exposed to the new coronavirus or showing related symptoms can be found within 24 hours and related epidemiological investigations can be carried out.

The New England Journal of Medicine published an analysis of 600,000 vaccinators from Clalit Health Services, which showed that 7 days after the second dose of the BNT162b2 vaccine, the risk of infection was reduced by 90%.

The study strictly matched the vaccinators and non-vaccinators for a comparative analysis, but the statistics of asymptomatic infections were a surrogate indicator (the nucleic acid was positive but no symptoms were recorded, rather than asymptomatic, which may include mild patients).

SIREN study: The risk of missing asymptomatic infections is small.
The study named SIREN is a prospective cohort study of staff (age ≥18 years) in public hospitals in the UK.

At first, it was to analyze the risk of secondary infection, and after the start of vaccination, the research plan was also adjusted and the effect of the vaccine was analyzed.

Before the start of the study, the subjects were divided into a positive group (8203 people) and a negative group (15121 people) based on the previous antibody or nucleic acid test results.
After that, their COVID-19 symptoms were collected every two weeks and performed every two weeks.
An asymptomatic nucleic acid test is performed once a month, and antibody tests are performed once a month.
In addition, all relevant test information except for the SIREN study is also included simultaneously.

At the same time, the research team collected their new crown vaccination information through the vaccine management system and questionnaires.

This strict monitoring program means that the risk of the research team missing asymptomatic infection is small, so the research data can provide a reliable estimate of vaccine prevention of infection in the real world.

SIREN study results: Two doses of BNT162b2 prevent 85% of infections.
The follow-up period for the published interim analysis is from December 7, 2020 to February 5, 2021.

A total of 23,324 subjects were enrolled in all 104 medical centers in England, with a median age of 46.
1 years and 84% of women.

As of February 5, 2021, the vaccination rate reached 89% (20641 people), of which 94% were vaccinated with the BNT162b2 vaccine and 6% were vaccinated with the ChAdOx1 vaccine (co-developed by the University of Oxford/AstraZeneca); 1607 were vaccinated (8%) completed two doses of vaccine, of which 1605 people (99.
9%) received the BNT162b2 vaccine and 2 people (0.
1%) received the ChAdOx1 vaccine. ▲Vaccination status of SIREN study subjects from December 7, 2020 to February 5, 2021: green and yellow are the first and second doses of BNT162b2 vaccine respectively; pink is the first dose of ChAdOx1 vaccine (picture source : Reference [1]) The infection and symptom data collected during the follow-up period showed that there were 977 new infections in the unvaccinated population, and the infection rate was 14 cases/10,000 person-days.

Within 14 days before and after the detection of nucleic acid positive, 620 people (63%) had typical COVID-19 symptoms, and 51 people (5%) had no symptoms.

The vaccinated population had 71 new infections 21 days after the first vaccination, with an infection rate of 8 cases/10,000 person-days; 7 days after the second dose of vaccination, 9 cases of infection occurred, with an infection rate of 4 cases/10,000 person-days.

Among all infected people after vaccination, 32 people (40%) have typical COVID-19 symptoms, and 10 people (13%) are asymptomatic.

Based on these data, the research team calculated: In the study population, the effectiveness of BNT162b2 vaccine in preventing infection (with or without symptoms) 21 days after the first vaccination was 70%, and the effectiveness of the second dose 7 days after vaccination was 85%.

In the previously uninfected population, the vaccine is more effective in preventing infection, with the effectiveness of 72% and 86% respectively 21 days after the first dose and 7 days after the second dose.

For previously infected people, the existing data are not enough to calculate the protective effect of the vaccine, but the data shows that the immunity stimulated by natural infection has a 90% preventive effect on subsequent infections.

During the study period, the main circulating mutant strain in the UK was B1.
1.
7.
Therefore, this also shows the effectiveness of the BNT162b2 vaccine against this mutant strain.

The enlightenment of WuXi AppTec's content team mapping for epidemic prevention and control.
The research team emphasized that these findings provide strong evidence that vaccination of working-age adults will greatly reduce new crown infections, including symptomatic and asymptomatic infections, and may therefore be helpful To reduce the spread of infection among the population.

However, the role of preventing transmission still needs more follow-up and more in-depth analysis to confirm.

On the other hand, vaccination cannot completely eliminate the risk of infection.
Therefore, it is still necessary to continue to take personal protective measures and receive regular asymptomatic nucleic acid tests.

Screenshot source: The Lancet In a review article published in the same journal of The Lancet, the team of Professor Eyal Leshem from Chaim Sheba Medical Center in Israel further emphasized the significance of this result for vaccination strategies: Currently, most epidemiology The authors believe that to achieve herd immunity, 70% of the population needs to obtain immunity through natural infection or vaccination.
Combined with the real data on vaccine prevention infection provided by the SIREN study, this means that in the case of unnatural infection, nearly 100% of the population is required Get one dose of vaccine or 80% get two doses of vaccine.

The review article also pointed out that there are two other important implications from the SIREN research data.

First of all, vaccinated people have fewer symptoms after infection.
Among the unvaccinated and vaccinated people, the proportions of typical symptoms before and after infection are 63% and 40%, respectively.

Although asymptomatic infection plays an important role in the spread of the virus, reducing symptoms may also reduce the infectivity of infected people after vaccination by reducing the viral load.

Secondly, it is still recommended to vaccinate the previously infected, but if the previously infected have a higher level of immunity, giving priority to the uninfected will help to achieve herd immunity faster.

In this study, people who are naturally infected can prevent 90% of subsequent infections, which is independent of the impact of the vaccine.

 The review article finally pointed out that the results of the SIREN study represent an encouraging "big step" and promote a better understanding of the substantive protective effects of BNT162b2 and other vaccines on infection, which is very important for controlling the spread of the new coronavirus in the community.

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How many people have been infected and died after receiving the new crown vaccine? The real data of 75 million vaccinators in the United States announced the introduction of Fosun Pharma, and the "Nature-Medical" published the first phase clinical data of the mRNA new crown vaccine for 500,000 vaccinations in the Chinese population, and no serious adverse reactions were found! National Medicines New Crown Inactivated Vaccine Safety Data Release Reference Materials[1] Victoria Jane Hall, et al.
, (2021).
COVID-19 vaccine coverage in health-care workers in England and effectiveness of BNT162b2 mRNA vaccine against infection (SIREN): a prospective, multicentre, cohort study.
The Lancet, DOI: https://doi.
org/10.
1016/S0140-6736(21)00790-X[2] Eyal Leshem, Benjamin Alan Lopman.
(2021).
Population immunity and vaccine protection against infection.
The Lancet, DOI: https://doi.
org/10.
1016/S0140-6736(21)00870-9 Note: This article aims to introduce the progress of medical and health research, not a treatment plan recommendation.

If you need guidance on treatment plans, please go to a regular hospital for treatment.