[ad_1]
This week, Johnson & Johnson will begin to distribute millions of doses of its coronavirus vaccine in the United States – after the “yes” of the US FDA – and in a few days, on March 11, also the EMA, the European agency of medicines. , should pronounce on its commercialization in the member states of the EU. But how is the green light decided for such an important tool to eradicate Covid-19? And, above all, how is the effectiveness of a vaccine measured and verified?
Von der Leyen, risky vaccines bought outside the European scheme
“The scientific community will never fully agree on the living nature of viruses,” two microbiologists recently wrote. That says as much about life as it does about viruses. Here is my essay for @nytopinion, adapted from my new book LIFE’S EDGE https://t.co/essF0OrB9L
– Carl Zimmer (@carlzimmer) February 26, 2021
the New York Times attempts to answer both of these questions in a lengthy article, written by science book author and columnist Carl Zimmer, and reporter Keith Collins. Efficacy, explains the “Gray Lady” of the American press, is “a crucial concept in vaccine testing, but also the most subtle.” This is because saying that a product is, say, 95 percent effective “does not mean that 5 percent of the people who get the vaccine will have Covid-19.” Not only. Just because one vaccine is more effective than another does not mean that it is actually the best option.
Let’s see why. In statistical terms, efficacy is a unit of measurement that defines how much a vaccine reduces the risk of contracting the disease. In conducting its clinical trials, Johnson & Johnson looked at how many people vaccinated with its serum contracted Covid and compared it to how many people (who had only received the placebo) also got sick. The difference results in the percentage declared by the producers. Zero efficacy means that vaccinated people are at the same risk as people who have not received the serum. One hundred percent means that the risk of contracting Covid was zero. In its tests conducted in the US, Johnson & Johnson measured 72 percent effectiveness for its single-use product.
Vaccini, started the table meeting at MISE to bring the production to Italy
But this figure changes depending on where the study is conducted. Johnson & Johnson also conducted trials in Latin America and South Africa, where the effectiveness was lower. This finding is also due to the presence of the South African variant B.1.351, capable of evading some of the antibodies induced by the vaccine. However, the effectiveness has not been eliminated, but in the African country it was equal to 64 percent. All in all, a very interesting result.
Johnson & Johnson, ok Ema expected on March 11: this is how the most anticipated vaccine “works”
Then there are other variables. The researchers found the Johnson & Johnson vaccine to be 85 percent effective against severe cases of Covid-19. This too, explains the New York Times, is an important fact, because it means fewer patients admitted to hospitals and fewer fatalities.
Another thing to consider when examining a vaccine (and when the EMA will consider its use in Europe) is the size of the sample examined. Johnson & Johnson, for example, had about 45,000 volunteers.
Vaccino, how the campaign changes with Figliuolo: 300,000 Civil Protection volunteers and 1,700 soldiers in the field
Goals for approval
The FDA had set a minimum target of 50 percent efficacy in vaccine trials with a “confidence interval” (that is, the range of plausible values for a certain parameter) of not less than thirty percent. However, protection comparable to that of flu vaccines, which save many lives each year.
So far, there are three vaccines allowed in the US, those of Pfizer and BioNTech, Moderna and Johnson & Johnson. AstraZeneca (adopted in Europe) and Novavax have not yet completed clinical trials in the United States, while Russian Sputnik has only published test results from Russia, but it has not yet been approved in Europe and the US (The problem, in the case of the Russian vaccine, these are the inspections that the EMA would like to carry out in its production centers, which are considered essential).
The EU Commission signs a new contract with Moderna
Nevertheless, comparing these vaccines would be impossibleexplains the American newspaper. This is because the efficacy of one may be superior to the other, but the “confidence intervals” may overlap, making them nearly equivalent. Another reason that makes this kind of comparison difficult is when effectiveness is measured. Johnson & Johnson, for example, did it 28 days after the single dose. Moderna did it 14 days after the second. However, all those licensed in the US greatly reduce the risk of contracting Covid-19. Not only that: they also greatly reduce hospitalizations and fatality. Johnson & Johnson, in this last point, has an efficacy of one hundred percent (with a confidence interval that goes from 74.3% to 100%): none of the vaccinated volunteers was hospitalized after the Covid infection, while 16 of the placebo group had to seek hospital treatment. .
In the next few months, other vaccines will be tested and efficacy will be measured based on the vaccines actually injected after approval. Therefore, it will be possible to have even more precise statistical data.
[ad_2]
