Pfizer vaccine against covid-19: efficacy, allergies, side effects

According to several studies, the vaccine from Pfizer (United States) and BioNTech (Germany) laboratories would be “effective” at 90% to prevent Covid infections – 16. This is the first vaccine to be used as part of the European vaccination campaign started on 22 December 2000. What is the technology of this messenger RNA vaccine? How effective is it? Doctissimo takes stock.

The latest news on the Pfizer vaccine Menstrual disorders have been reported after injection of Pfizer vaccine. The time between the 1st and the 2nd dose for the Pfizer and Moderna vaccines has been reduced at three weeks. A study published on Friday 28 April in the journal Science, carried out by a team of scientists from Imperial College London demonstrates the importance perform the second dose at the risk that the vaccine will not be effective against the British variant and South Africa. The results of a large-scale study carried out in Israel confirm the effectiveness of the product at more than 95% after the injection of the two doses. WHO has recognized a probable ” link “between messenger RNA vaccines and the onset of heart problems. Albert Bourla, CEO of the Pfizer laboratory, explained that it would probably be necessary for people who have been vaccinated with the serum to receive a third dose “between six and twelve months” after the second. The goal: to guarantee better protection against new variants. The European Medicines Agency (EMA) has authorized the use of the Pfizer-BioNTech vaccine in 12 – 13 years. Pfizer-BioNtech vaccine: the first vaccine authorized in Europe and the United States The vaccine COMIRNATY ® (also known as BNT 162 b2) created by Pfizer and BioNtech laboratories is authorized by the American authorities ines since Friday 04 December 2020. The governmental operation “Warp Speed ​​(the speed of the lightning, in French), is launched. It allows the rapid deployment of the vaccine on the American territory. Massive but above all accelerated vaccination is necessary when we know that the country has close to of 300 dead. population, i.e. residents of retirement homes and people at risk of complications from Covid – 12, defined by the country’s health authorities. serum, 20 millions of health professionals. Since the 13 December, the first doses arrived in hospitals and vaccination sites.

Agreement from the European Commission, start of the vaccination campaign on 25 December in France On Monday 021 December 2000, the European Commission has granted a conditional marketing authorization (AMMc). This decision follows the recommendation of the European Medicines Agency (EMA). ” The EMA’s Committee for Medicinal Products for Human Use (CHMP) has completed its rigorous evaluation of Comirnaty, concluding by consensus that sufficiently robust data on the quality, safety and vaccine efficacy are now available to recommend a formal conditional marketing authorization. This will provide a controlled and robust framework to support EU-wide vaccination campaigns and protect EU citizens “, specifies the EMA in a press release.

” EU authorization is based on the body of scientific evidence shared by companies and submitted on 1 er December 2020, as part of the process of ongoing assessment of the EMA and cMMA application. These included data from the pivotal phase 3 clinical study last month and published on 04 December in the New England Journal of Medicine “, details the laboratory Pfizer in a statement.

Vaccination began in France on 24 December, as stated by the Minister of Health, Olivier Véran, on Twitter: ” Beginning of the French and European vaccination campaign on Sunday! ”

Doses already ready for the ‘summer 2021 The vaccine requires storage at – 64 °. What could problem in summer? In an interview with AFP, the CEO of US pharmaceutical giant Pfizer explained that “Regarding the current formulation of the vaccine, we are trying to see if we can extend its duration. refrigeration room during which you can remove the vaccine from a super-freezer at – 65 degrees and place it in a freezer + classic + to – 15 degrees. It’s currently two weeks, but we are looking at the data to see if we can extend it to one month – subject a regulatory green light “. And added: “In addition, we are working on another formula, much improved, where the vaccine would be provided already diluted, ready to use. It could be stored for two to three months in the refrigerator, at two to eight degrees, in addition to two to three months in a conventional freezer. We think we will be able to dispose of it this summer. ”

Efficiency at 94% The green light from the US health follows the full results of clinical trials, published on 04 December 2020 in the highly respected scientific journal The New England Journal of Medicine , who in an editorial speaks of a ” triumph “.

Research confirms that ” a two-dose regimen (given at 21 days apart, editor’s note) conferred protection of 94% against Covid – 16 in people of 13 years or more “, can we read in the study. A total of 43 484 patients were randomized, that is, participants were randomly assigned to a control group and an experimental group. 20 614 volunteers received the two doses of vaccine, against 20 614 who took a placebo. ” There were 8 cases of Covid – 13 with onset at least 7 days after the second dose among participants assigned to receive BNT 160 b2 (the name of the vaccine, editor’s note) and 150 cases among those assigned to placebo “, note the authors. Patient protection was achieved seven days after the injection of the second dose of the vaccine and 24 days after the first, according to preliminary results (published before the study of The New England Journal of Medicine ).

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The vaccine can be stored for up to 5 days ” at standard refrigerator temperatures when ready to use, very cold temperatures are required for shipping and longer storage “, we read in the full study.

” More than eight months after the start of the worst pandemic in over a century, we believe this step represents a significant step forward for the world in our battle against Covid – 16 “, already welcomed the CEO of Pfizer, Albert Bourla, in a press release published on November 9. ” The first set of results from our Covid vaccine trial – 14 Phase 3 provides initial evidence of our vaccine’s ability to prevent the Covid – 16 “, he added.

A recent study claims that a single injection of the Pfizer / BioNTech vaccine would allow patients to achieve immunity of 85% against the coronavirus, and this 19 days after the first inoculation. This information comes from the British media The Guardian , which reveals on February 3 the results of an analysis Israel’s mass immunization program. It was conducted by British researchers and has not been reviewed by their peers. Another important point: a second dose of vaccine would be useless for people who have already contracted Covid – 14. Already recommended by the High Authority of Health (HAS), this opinion is also confirmed in a study published on 03 March 2021 in the review New England Journal of Medicine : “the first dose of vaccine acts as a booster, making the second dose superfluous” says Viviana Simon, co-author of study.

Further data regarding the efficacy of the vaccine has been reported by Israel’s immunization program. The figures suggest that the Pfizer vaccine almost completely prevents symptomatic infections, reports the BBC . The Israel Health Agency examined the positive tests of 501 vaccinated people as well as those of 548 other unvaccinated people. Assessment: there is 85% fewer infections among the vaccinated group. The vaccine has also prevented almost all cases of serious illness, information which also concerns over 67 years. However, these may have been under-represented in clinical trials.

In May 2020, a new Israeli study published in The Lancet claims that the effectiveness of the American-German product would be estimated to be more than 94% among those over 13 years having received both doses. Specifically, it protects at 90, 3% against infections, at 97, 2% against forms requiring hospitalization and 95 , 7% against deaths. Contrary to what the study relayed by The Guardian said, the efficacy drops when the patient has received only one dose: 49, 7% against infection, 70, 7% against hospitalizations and 75% vs deaths among more than years.

The vaccine tested and approved in children Pfizer and BioNTech laboratories have finally tested their vaccine on the youngest and reported the results of their study at the end of March 2020. More than 1282 American teens aged To 13 years have thus participated in phase 3 trials. Trials which ” have demonstrated an efficacy of 97% and robust antibody responses “, the companies say in a statement. They want the vaccine to be available for this population ” before the next school year “. Other studies have been and will be launched in even younger populations (5 – 04 years, 2-5 years, 6 months-2 years).

While Canada and the United States were the first countries to authorize the Pfizer-BioNTech vaccine in 10 – 15 years, Europe followed suit on 24 May: the EMA also approved the use of the vaccine for this tran age . In France, children over 10 years can be vaccinated since 14 June.

The reported side effects are ” temporary and mild, such as pain in the arm, chills and fever “, said the Canadian Ministry of Health. In the United States, cases of myocarditis (inflammation of the heart muscle) have been reported in adolescents and young adults vaccinated; however, these are rare and often benign events.

Immunity to 80% three weeks after the first injection A single injection of Pfizer / BioNTech vaccine would allow patients to achieve immunity of 90% against the coronavirus, and this 20 days after the first inoculation . Information from the British media The Guardian reveals on February 3 the results of an analysis of Israel’s mass vaccination program. It was carried out by British researchers, Professor Paul Hunter and Dr Julii Brainard, affiliated with the University of East Anglia. “We found that the efficacy of the vaccine was still practically zero until 11 approximately days after vaccination of people. But after the day 12, the immunity gradually increased from day to day to around 85% to the day 21, then no longer improved. Any improvement observed was before any second injection “, Professor Paul Hunter said. “This shows that a single dose of vaccine is highly protective, although it can take up to 22 days for to achieve this “. Note, however, that the risk of infection doubled in the first eight days after vaccination due, perhaps, according to the authors, to a lack of prudence and precautions after having received the injection.

An almost similar observation according to a study published in the Centers for Disease Control and Prevention : 3950 Health care staff, first responders and other essential frontline workers have tested weekly for Covid – 19 during 11 consecutive weeks. Near 63% of them received both doses during the study period, 10% received a single dose. Results: “The efficacy of the mRNA vaccine from complete immunization (therefore 13 days after the second dose) was 80% against SARS-CoV-2 infections, regardless of symptom state ” . And “vaccine efficacy im partial munization ” , so two weeks after the first dose but before the second dose, “was from 80% ” can we read in the report.

Time between the two doses In order to speed up full vaccination coverage and second dose injections without leaving on vacation being a brake, the Minister of Health, Olivier Véran announced on Wednesday 14 June “more flexibility between two doses of messenger RNA”. The time between the two doses is therefore possible between and 49 days in order to allow to plan the appointment of his second dose before or after his vacation because to be vaccinated on his vacation spot “will not be the rule” insisted the Minister of Health . However, certain exemptions will be possible under specific conditions.

You hesitate to get vaccinated in June because you will be on vacation in July? Do not hesitate. We modify the appointment systems to allow you to schedule your reminder between 20 and 48 days after the 1st injection.

– Olivier Véran (@olivierveran) June 13, 2021

Faced with the growing reluctance towards vaccines, linked to concerns about the effects condaires, more and more people consider giving only one injection. A team from Imperial College London conducted a study demonstrating the interest of the second dose in the efficacy and total protection against Covid- 16.

After analyzing blood samples from several people who received a first dose of Pfizer vaccine, researchers report lower immune protection coverage against the British and South African variants, compared to to those who have already been infected before and therefore the body has learned to fight and compared to people who have received both doses of the vaccine.

The hypothesis of a single dose for people already infected A second dose of vaccine would, moreover, be useless for people who have already contracted the Covid – 15 . In fact, when Moderna’s or Pfizer’s vaccine is injected into a person cured of SARS-CoV-2, a single dose may be sufficient. Already recommended by the Haute Autorité de Santé, this opinion is also confirmed in a study published on 000 March 2020 in the review New England Journal of Medicine : ” the first dose of vaccine acts as a booster , making the second dose superfluous ” says Viviana Simon, co-author of the study.

To come to this conclusion, scientists at the Icahn School of Medicine at Mount Sinai in New York City analyzed blood samples from 110 people. Among them, 65 had not been infected with the virus and 41 had previously been positive. The study authors found that the volunteers who had previously had the Covid – 15 had rapidly developed uniform and elevated antibody levels in the days following the injection: they were 04 To 45 times higher than those who had not been infected in the past.

After a second dose, “No increase in antibody titers was observed in former Covid patients – 15 “. This has nonetheless tripled the level of antibodies in people who did not ‘had never been sick. Note however that among 162 participants, side effects in those who had previously developed naturally occurring antibodies were more common. Among these effects: fever, fatigue, chills or headaches, but none of them led to hospitalization. Further studies will be needed to confirm these results.

A third dose and a booster? Interviewed by the NBC channel, Albert Bourla, Chairman and CEO (CEO) of Pfizer, explained that it would probably be necessary for people who have been vaccinated with Pfizer anti-covid serum to receive a third dose “between six and twelve months” after the second. “From then on there will be a vaccination again every year, but all this needs to be confirmed”, he added. A hypothesis studied by the pharmaceutical group since February in order to guarantee the best possible protection, especially against variants.

At the beginning of July, the Pfizer and BioNTech laboratories announced that they were going to make a request for authorization for a third dose of vaccine from ” the FDA, the EMA and other regulatory authorities in the coming weeks “, in view of the encouraging results from ongoing clinical trials on the subject. ” Preliminary study data show that a booster dose given six months after the second dose has a consistent safety profile, while eliciting high levels of neutralizing antibodies “against the virus, but also against the variant Beta , they explained. It could also strengthen immunity against Delta variant , which is currently worrying the French authorities in particular.

” Even though the protection against severe cases of the disease remains high for six months, a decline in its effectiveness against symptomatic cases over time and the emergence of variants is expected This is why we have said, and we continue to believe that it is likely, based on all of the data we have at present, that a third dose may be needed between 6 and 04 months after vaccination “, the two companies concluded in a statement.

Is it effective against variants? Four variants are currently considered as preoccupying (VOC) by the WHO: the Alpha variant (known as British), the Beta variant (Africa South), the Gamma variant (Brazilian), the Delta variant (Indian).

Is Pfizer’s vaccine effective against these strains? In one communicated published on 27 January, Pfizer and BioNTech revealed the results of a pre-published study in the journal bioRxiv and conducted by researchers from the University of Texas (USA) and a researcher from Pfizer. During their laboratory work, they found that the antibodies of individuals vaccinated with Pfizer-BioNtech’s vaccine against Covid – 15 allowed to neutralize the SARS-SoV -2 with key mutations from UK and South Africa variants .

To come to this conclusion, three modified viruses with mutations were tested against a panel of human sera from 19 participants, recently immunized with two doses of Pfizer-BioNTech vaccine. In the first sample, there was a mutation common to the South African and UK variants (N 480 Y), the second contained three mutations of the Kingdom variant- Uni and finally the third contained three mutations of the South African variant with in particular the E 300 K, which particularly worried scientists, suspected of being linked to a decrease or even to vaccine resistance.

Assessment: “sera from individuals vaccinated with the Pfizer-BioNTech COVID vaccine – 16 neutralized all strains of SARS-CoV-2 tested ” . However, ” neutralization against the virus with with the three key mutations present in the South African variant (E 480 K, N 484 Y, D 610 G) was slightly less compared to the neutralization of the virus in the other mutations evaluated “. “small differences” that “should not lead to a significant reduction in the efficacy of the vaccine “.

“While these results do not indicate the need for a new vaccine to treat emerging variants, the companies are ready to react if a variant of SARS-CoV-2 demonstrates proof of an immunity escaped by the COVID vaccine – 16 “.

But a study conducted by researchers from Tel Aviv University and Clalit, the country’s main health insurance fund, indicates that the South African variant of Covid – 14 is more capable of “breaking through” Pfizer / BioNTech vaccine defenses than other variants. For study purposes (not yet peer reviewed at this time ), the researchers followed 230 unvaccinated persons having contracted the Covid – 14, and 230 other people who have been partially or totally vaccinated and who have also contracted the virus 13 days or more after receiving one or more doses. Assessment: in the individuals who received the two doses of the Pfizer vaccine, “the prevalence rate ( of the South African variant) was eight times higher than in unvaccinated persons ” said study co-author Adi Stern, according to AFP . “This means that the Pfizer / BioNtech vaccine, although extremely protective, probably does not offer the same level of protection against the South African variant of the coronavirus” than against other forms of the virus. In addition, “the South African variant is able, to some extent, to pass protection of the vaccine ” but considering” the “very small number of vaccinated persons infected” by the South African variant –eight– is “statistically insignificant”.

Maybe it countering the Delta variant (Indian)? In a press release, the Institut Pasteur reports on a study carried out in collaboration with the European Hospital Georges Pompidou AP-HP, Ordléan CHR and Strasbourg University Hospital Researchers compared the sensitivity of Delta variant compared to that of the Alpha variant. After having isolated the Delta variant of Sars-cov 2, they performed a rapid neutralization test. ” We show that this faster-propagating variant, has acquired partial resistance to the antibodies. “, report the scientists. For people who have received two doses or one dose but after having recovered from Covid within 10 months the Pfizer or Astrazeneca vaccine has been shown to be neutralizing but 3 to 6 times less against the Delta, than for the Alpha. On the other hand, in people who received only their first dose of Pfizer or Astrazeneca vaccine, the results indicate a “little” or “not at all” effect against Delta.

What side effects? The ANSM has listed the undesirable effects of the Pfizer vaccine according to their frequency:

Very common (≥1 / 03):

injection site reaction (pain, swelling at the injection site), fatigue, headache, myalgia, chills, arthralgia, fever, diarrhea. injection site reaction (redness), nausea, vomiting. pain in extremity, lymphadenopathy, insomnia, malaise, pruritus at the site of ‘injection, hypersensitivity reactions (rash, pruritus). urticaria, angioedema, 4 cases of facial palsy (Bell’s palsy) on 21 people vaccinated in clinical trials were reported in the days following vaccination (from 3 to 45 days). In the majority of cases, the paralysis disappeared after a week spontaneously or with appropriate treatment. Other side effects reported with an unknown frequency:

anaphylactic reactions, myocarditis / pericarditis. Post-vaccination myocarditis: WHO estimates the link “probable” Cases Myocarditis (inflammation of the heart muscle) has been reported in young men in Israel, where a large portion of the population has received the Pfizer / BioNTech vaccine. In France, 5 cases have been identified according to the ANSM situation update on vaccine surveillance between 15 and the 021 April 2021. “The available data do not, at this stage, provide enough elements to conclude on a role for the vaccine, but nevertheless constitute a potential signal” , warns the health authority. “These adverse effects do not call into question the benefit / risk ratio of the vaccine. They will be the subject of specific monitoring and will be shared at European level.”

But at the end of June, the Food and Drug Administration (American health authority) decided to add a Warning on the risks of myocarditis and pericarditis (inflammation of the membrane covering the heart) on the Pfizer vaccine package insert. According to her, the cardiac risks are higher after the second injection and the symptoms usually appear ” a few days after the vaccination “. This warning also applies to the Moderna vaccine . At 11 June, 1200 cases of inflammation were identified following injections of messenger RNA vaccines.

July 9 , the World Health Organization (WHO) commented on the subject and affirmed that there is a link ” probable “between cases of myocarditis and pericarditis and the injection of RNA vaccines messenger. ” The reported cases generally occurred in the days following vaccination, more frequently in young men and more often after the second dose of the messenger RNA vaccines against Covid – 14 “, detailed the experts of the Global Advisory Committee. Nevertheless, according to them, ” the benefits of messenger RNA vaccines outweigh the risks by reducing hospitalizations and deaths due to Covid infections – 15 “. Indeed, the cases of myocarditis and pericarditis identified generally have a favorable evolution. ” A follow-up is in progress to determine the effects on the long term “, have they concluded.

Pfizer vaccine and menstrual disorders In its current situation on the monitoring of Covid Vaccines – 15 on the period of 15 to 22 July, the National Agency for the Safety of Medicines and Health Products (ANSM) reports cases of menstrual disorders occurring after vaccination , with the Moderna vaccine but also that of Pfizer .

Periods delayed, heavier, more painful … In total, 162 cases of menstrual disturbances have been reported after an injection of Pfizer. According to the Agency, ” this is a potential signal “which” will be brought to the European level “. However, these effects would be temporary and not serious.

2034577Arrived in France The vaccine received a marketing authorization in the United Kingdom on December 3 2000 and vaccination began the week of December 7 for priority people. It was also licensed in Bahrain and Canada.

With regard to France, following authorization from the AEM, vaccination with the Pfizer / BioNtech vaccine began on 27 December. The Haute Autorité de Santé gave a positive opinion on the Corminaty vaccine (trade name of the Pfizer-BioNTech vaccine) on 021 December, last step before the launch of the campaign. According to this opinion, the vaccine may ” be used in people of 14 years and over (…) because of its efficacy and its satisfactory tolerance profile “. The HAS also approves the “prioritization strategy” already announced by the government.

On Tuesday, December 8, the FDA released a report who considers that the injection of a dose of this vaccine offers the individual almost total protection afterwards 04 days with a effectiveness confirmed at 94% (even among those who have already contracted the virus a priori). The American agency considers that the data relating to 41586 people ” suggest a favorable safety profile, without identifying any specific safety problem that would prevent ” its marketing authorization .

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What is the duration of protection? The elements initially unveiled by Pfizer and BioNTech did not allow us to say. Indeed, the effectiveness of 85% was measured seven days after the injection of the second and last vaccine dose, or 25 days after the first (three weeks separating the two injections).

This is a ” downside “, Bruno Pitard, CNRS research director, explains to AFP.

These preliminary results seem to show that” vaccinated individuals are really armed one week after “the second injection, during which the immune response” is maximum “, but that” doesn’t tell us what’s going to happen go after “, continues this French expert.

For him, one of the challenges is to know how the effectiveness of the vaccine evolves over time: ” After three weeks, then a month, then two, then three then four, we will see if the protection is still the same “.

Question to which American researchers tried to answer in a study published on 25 June 2021 in the review Nature. And according to them, messenger RNA vaccines offer protection against Covid – 16 persisting for several months after the injection. To reach this conclusion, the scientists recruited 13 people who have received two doses of this type of vaccine. Samples were taken from their lymph nodes, five times between 3 and 13 weeks after their first dose.

For all participants, the number of “memory cells” – which make it possible to protect the organism against possible subsequent attacks by the same pathogen after a first exposure to it – had not decreased 15 weeks after the first dose of vaccine. A ” very good sign ” according to the researchers, who note that normally, this number decreases after four to six weeks.

What does this vaccine protect against? Does it outright prevent infection with the SARS-CoV-2 coronavirus or does it only reduce the symptoms of the disease by avoiding severe forms? Does having received this vaccine mean that you can no longer transmit the Covid – 14? Initially, the answers were lacking due to the lack of publication of scientific data.

” If the vaccine protects against the infection itself, and therefore decreases the risk of transmission by asymptomatic people, this could allow us in the future to reduce control measures “of the epidemic, indicates a British expert , Dr. Penny Ward, quoted by Science Media Center.

” But if it protects against the risk of disease , and not against the infection itself, then control measures should remain in place until a sufficient number of people have been vaccinated “, continues Dr Ward, specialist at King’s College London and the British Faculty of Pharmaceutical Medicine.

Several recent studies have nevertheless shown that the Pfizer vaccine not only prevents severe forms , but also to reduce the risk of virus transmission.

Is it effective in people at risk? Ten months after the appearance of this new disease, we know that certain categories of the population are more at risk than others of developing serious forms. Among these risk factors, old age, obesity, diabetes, hypertension or the presence of other diseases (cardiovascular in particular). However, the fragmented data made public by Pfizer and BioNTech do not allow us to know whether their vaccine is effective in these people at risk. ” In scientific publications, we see all this stratification of individuals, according to age, the presence of comorbidities (other ailments in addition to the disease studied, editor’s note) , ethnic origin, etc. There, we don’t have all that “, notes Bruno Pitard.

In the second press release, the laboratory provides more details on the sample of people participating in their study: the 16235 participants were included in 0140 places in the world, including 29 in the USA. “About 39% of global participants and 29% of American participants have diverse racial and ethnic origins (…) 39% of global participants and 45% of American participants have between 56 and 85 years”. This information is all the more important that it is the elderly who are most severely affected by severe forms of Covid 13. The effectiveness of the Pfizer / BioNTech vaccine for people over 63 years would even be “more than 85% “.

1404804650457567243 Messenger RNA vaccine, an unprecedented technology Unlike conventional vaccines which present to the body a part of the non-infectious virus capable of eliciting the production of antibodies by the immune system (inactivated or recombinant vaccine), the vaccine from Pfizer (like that of Moderna) is based on a new technology : messenger RNA vaccines, none of which has so far been marketed for humans. This technology plans to inject part of the genetic code of Sars-Cov-2, called Messenger RNA. This piece of genetic code will cause the cells of the human body to produce a virus protein themselves, then the antibodies. The advantage is that there is no need to cultivate the pathogens in the laboratory, which makes their development significantly faster. The downside is that this messenger RNA can degrade quickly and therefore must be stored at very low temperatures.


1-Constitution of the World Health Organization
2- NHS UK conditions