Which novel coronavirus vaccine works best?

In the face of the cunning new coronavirus, human beings have been engaged in a long and dark struggle for 15 months, paying a heavy price of over 136.99 million people infected and 2.95 million people dead

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As of 14:50 CEST on April 14, 2021, according to who statistics, 136996364 people have been diagnosed and 2951832 people have died| www.who.int Fortunately, with the launch of mass vaccination programs in many countries and regions around the world, we finally see the dawn of ending the epidemic

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On February 3, 2021, the number of people vaccinated with the novel coronavirus vaccine exceeded the number of people infected

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By the time of publication, 806 million doses of novel coronavirus vaccine had been inoculated around the world“ Have you been vaccinated? ” It has become the most popular greeting nowadays

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Before the advent of the novel coronavirus vaccine, it generally takes 5-20 years for a vaccine to be developed and put on the market

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Most vaccines have been developed for more than 10 years

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We have been familiar with influenza vaccines for 14 years, polio vaccines for 20 years, and smallpox vaccines for 26 years

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Under the pandemic, there is no vaccine like the novel coronavirus vaccine that everyone is looking forward to

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People didn’t wait long

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In the past year, the novel coronavirus vaccine has gone from research and development to rapid vaccination

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Its scale and speed have set a historical record

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According to who statistics, so far, nearly 200 new coronal vaccines are under development, and 13 of them have been approved for marketing in at least one region

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Over the past year, the novel coronavirus vaccine has gone from research and development to rapid vaccination| www.who.int In the face of a new virus, the world needs a variety of different types of vaccine candidates to maximize the chance of finding a successful solution

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But with the increasing variety of vaccines on the market, people can’t help asking a question before deciding to vaccinate: which new vaccine is the best? It’s not just the people who are curious

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This problem is also a common problem faced by researchers and governments all over the world

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Decision makers naturally expect to choose the most promising one to end the epidemic

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But between vaccines and vaccines, how can we compare them? Before answering this question, let’s find out which vaccines are available and what the efficacy of vaccines represents

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What is the efficacy of the new vaccine? At present, the phase III clinical data of Pfizer / biontech, Modena vaccine and Russia’s “satellite 5” vaccine show that the effective rate is more than 90%; The effective rate of Oxford / AstraZeneca vaccine was 62% – 90%

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The effective rate of Sinopharm group’s vaccine, which is being widely spread in China, is 79%, and that of Kexing biology’s vaccine is 50% – 83%

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According to the phase III clinical data of adenovirus vector vaccine jointly developed by academician Chen Wei of Academy of Military Sciences and kangxinuo biology, the overall effective rate is 65.7%

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These vaccines are beyond the WHO recommended protection rate of more than 50% marketable threshold

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At present, some novel coronavirus vaccines have been popularized all over the world| www.gavi.org The above-mentioned vaccine efficiency actually refers to “protective efficacy”, that is, the protective effect of a certain vaccine on diseases in clinical trials, including whether it can prevent infection, reduce severe cases and even prevent death

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In the phase III clinical trial of the novel coronavirus vaccine, the researchers will randomly assign the subjects to the vaccination group or the control group, and then observe their final diagnosis of the novel coronavirus

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At the end of the clinical trial, the incidence rate of vaccine group was 1% and the incidence rate of control group was 10%

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The protective rate of vaccine was (10%-1%) /10%=90%, that is to say, the protective efficacy of vaccine was 90%

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Taking the novel coronavirus vaccine mRNA-1273 of mod ner as an example, the three phase of vaccine group and control group had 15210 patients, and the final vaccine group had 11 cases of symptomatic confirmed cases (incidence rate 0.072%), 185 cases of control group (incidence rate 1.216%), so the protective efficacy of this vaccine was 94.1%

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This means that in this trial, vaccinated people are 94.1% less likely to be infected with the novel coronavirus than non vaccinated people

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Before it is approved for wider use, the new vaccine has to go through three phases of clinical trials| www.who.int Does this mean that the more effective the vaccine is in clinical trials, the better it will be in reality? Not at all

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The efficacy data of vaccines in different clinical trials will be affected by many factors, which also makes it difficult to directly compare different new vaccines

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First of all, the clinical endpoint indicators, the interval of vaccination, the vaccinated population and age, and the classification criteria of mild and moderate diseases are different for each vaccine clinical trial

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These differences will directly lead to the difference of test results

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Taking the endpoint as an example, should researchers choose infection or morbidity as the boundary of comparison? If you choose infection, which index should be taken as the criterion, and if you choose onset, which symptoms should be selected? For new vaccine trials, each index has no previous experience to follow, so the clinical endpoints selected by different studies are not the same

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For example, the patients counted by Kexing vaccine are all patients above level 2 in the WHO agreement, including those with only mild symptoms without medical intervention, that is, those with very mild symptoms

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Pfizer clinical trials, the statistics are confirmed by nucleic acid testing and a symptom of infection

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Even for the same symptom, due to different details, people who are counted as infected in one vaccine clinical trial are uninfected in another

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For example, if only fever symptoms, modner test will not count as infected, but Pfizer test will count in

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In the clinical trial of kesing vaccine in Brazil, according to the specific temperature, it may be classified as grade 2 or above

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Secondly, each vaccine clinical trial was carried out in different regions, at different times and with different strains prevailing at that time

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This adds countless different variables to each experiment

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Due to the influence of these variables, we can see that the clinical trials of different vaccines, and even the results of the same vaccine in different regions, may be very different, which also makes it impossible to judge the performance of a vaccine in the epidemic situation just by looking at the data of the protective effect obtained from the trials

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Is it impossible to compare vaccines in practice? Generally speaking, the most accurate way to compare two (or more) drugs (including vaccines) is head to head comparative study

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This is a “non placebo-controlled” trial in which the drugs or treatments that you want to compare are compared in the same clinical trial

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In the head-to-head study, it is divided into “superiority” study and “equivalence and non inferiority” study

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As the name suggests, superiority study is to directly verify whether a drug is superior to another drug and has stronger efficacy and safety

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In the future, if there are trials to conduct head-on trials on the approved vaccines, it is possible to relatively objectively distinguish the advantages and disadvantages

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But even in head-on studies, the “good” or “bad” of vaccines can not be judged by a single indicator

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Many people judge vaccines on the basis of their data on prevention of infection

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But in addition to the prevention of infection, the novel coronavirus vaccine can also prevent the hospitalization, severe illness and mortality of novel coronavirus patients

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The data so far show that vaccines on the market are much more effective than symptomatic treatment in these aspects.

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