The data coming to us from several countries are consistent on the effectiveness of vaccines. What about Pfizer and Moderna?
For several months now, a number of vaccines against the SARS-CoV-2 coronavirus have been in use around the world. Vaccination is particularly well advanced in Israel, the United Kingdom and the United States, from which data are being taken in real conditions. Do Pfizer and Moderna vaccines prove their effectiveness in the field?
A study conducted by the CDC on a cohort of 3,950 people (mainly caregivers), and published this Monday, March 29, 2021 in Morbidity and Mortality Weekly Report, comes to the conclusion that ” mRNA vaccines against Covid-19 disease are highly effective in preventing infections under real conditions “. This applies to both the Pfizer vaccine and the Moderna vaccine.
According to these results, vaccinated people have a 90% less chance of contracting the disease after the second dose (full vaccination), a figure that remains at 80% after a single dose (partial vaccination). In full numbers, there were 161 coronavirus infections in the unvaccinated group; 16 infections in people who received a first dose; 3 infections in those who received both doses. Vaccines also slow down severe forms of the disease.
The CDC recalls from these results that “ Covid-19 vaccination is recommended for all eligible persons “. In the United States, the use of mRNA vaccines from Pfizer and Moderna is predominant. To date, nearly 140 million doses have been injected on U.S. soil and Joe Biden has said 90% of adults may be eligible by April 19.
Israel is also one of the countries where coronavirus vaccination is advancing at a leading rate. The rate is 114 per 100 inhabitants, which means that a major part of the population has received one dose, or even both, and that the country is approaching collective immunity (rate of 120 doses per 100 inhabitants) .
In recent months, the country has therefore been the subject of studies in real conditions on the effectiveness of the Pfizer vaccine, almost the only one used on Israeli territory. A first set of data has been published in a scientific journal (The New England Journal of Medecine), February 24. Based on a group of 600,000 people vaccinated and another group of 600,000 people who were not yet vaccinated during the study, the data shows that Pfizer’s vaccine reduced symptomatic infections by 94%. For people infected despite vaccination, severe forms are reduced by 92%.
Other more recent data was released in mid-March 2021, but it has not yet been published in a scientific journal, only accessible by press release. According to these recent results, on a large scale the Pfizer vaccine would be 97% effective against symptomatic cases, critical hospitalizations and deaths; and it would slow down asymptomatic transmissions by 94%. ” The incidence rate in the fully vaccinated population has dropped massively compared to the unvaccinated population, showing a marked decline in hospitalized cases from COVID-19 The Israeli health ministry commented.
In the UK, both AstraZeneca and Pfizer vaccines are used. The country has been vaccinating on a large scale since the start of the year – 33 million doses have been administered to date.
For this country, we have preliminary data (not published in a scientific journal), which is based on more than 7 million adults aged 70 and over. The scale is larger compared to other studies, but more restricted in population targeting, which makes it a very specialized scope. If we focus on the Pfizer part of the study, then:
- Efficacy is 57 to 61% after a dose of Pfizer against symptomatic infection, in those over 70 years of age;
- A single dose of Pfizer reduces the risk of hospitalizations by 80% in people over 80 years of age;
- Pfizer’s vaccine reduced deaths caused by Covid-19 in this same population by 85% (those over 80).
In short, consistent results
As with AstraZeneca, consistency is starting to emerge between the different analyzes carried out in real conditions. If the figures still vary according to the studies and according to the populations studied, the concrete impact of Pfizer’s vaccine on the reduction of symptomatic infections and severe forms of the disease is no longer to be proven, whether after a first dose or even more after a second.
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