COVID VACCINE. Only Pfizer and Moderna vaccines can be given as a booster against the coronavirus (3rd dose). What differences? Which one to choose ? And for a first vaccination? Which is the most effective? Against variants?
[Mise à jour le 23 décembre 2021 à 18h35] The vaccines from Pfizer and Moderna against the coronavirus are the most administered in France. According to figures from theANSM, as of December 9, 2021, out of more than 111 million injections against the Covid carried out, more than 90 million were released with Pfizer’s vaccine and 12 million with that of Moderna (7.8 million for the AstraZeneca vaccine and 1 million for the Janssen). Those two vaccines are based on the principle of RNA messenger. Their mode of action to protect themselves from Covid is the same: a genetic sequence of the virus (DNA or mRNA) is injected and enters the interior of the human cell. This will use it to produce the associated viral protein (Spike) which will trigger the immune system. They are both carried out with 2 doses as a primary vaccination followed by a third dose as a booster. So what differences ? In terms ofSide effects ? Efficiency ? We take stock.
Which vaccine can be given to people over 30?
The latest pharmaco-epidemiology data transmitted by the ANSM and the Health Insurance as part of the Epi-PHARE study confirmed the risk of occurrence of very rare cases of myocarditis favorable development, more with the Moderna vaccine and in men under 30. Thereby Moderna’s Spikevax vaccine is only administered in France for over 30s, whether as a primary vaccination or as a booster. Pfizer’s vaccine can be taken from the age of 5 (at a reduced dose for 5-11 year olds then at full dose as for adults for 12-17 year olds).
What are the differences in their composition?
Pfizer’s Comirnaty vaccine has a lower RNA dosage than Moderna’s: it contains 30 micrograms of RNA in primary vaccination and as a booster against 100 micrograms of RNA for Moderna’s Spikevax in primary vaccination and 50 micrograms in dose of booster (half dose).
| Pfizer vaccine | Moderna vaccine |
|---|---|
30 µg of mRNA vaccine | 100 µg of mRNA vaccine |
Excipients : ((4-hydroxybutyl) azanediyl) bis (hexane-6,1-diyl) bis (2-hexyldecanoate)) (ALC-0315) 2-[(polyéthylène glycol)-2000]-N, N-ditetradecylacetamide (ALC-0159) 1,2-Distearoyl-sn-glycero-3-phosphocholine (DSPC) Cholesterol Potassium chloride Monopotassium phosphate Sodium chloride Disodium phosphate dihydrate Sucrose Water for injections | Excipients : SM-102 lipid Cholesterol 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]) 1,2-Dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000 (PEG2000 DMG) Tromethamine Tromethamine hydrochloride Acetic acid Sodium acetate Sucrose Water for injections |
Which is the most effective?
| Pfizer vaccine (2 doses) | Moderna vaccine (2 doses) | |
|---|---|---|
| Efficacy original virus Sars-Cov-2 | 95% against severe forms / 60% against contaminations * | 92% against serious forms / 60% against contamination ***** |
| Delta variant efficiency | 80 to 95% against severe forms / 40% against contaminations ** | 95% against serious forms / 40% against contamination ***** |
| Omicron variant efficiency | 70% against severe forms / 33% against contamination *** | NC |
* Pfizer / WHO
** Pfizer /CDC/ WHO
*** South African Discovery study
**** Moderna / WHO
***** CDC / WHO
Which booster vaccine?
In accordance with the recommendations of the High Authority of Health, the vaccine booster against the Covid is carried out with a full dose for the vaccine of Pfizer, and with a half-dose for that of Moderna. Moderna vaccine can only be given as a booster to people over 30 years of age because of the risk of developing “very rare cases of myocarditis” reminds HAS: “In the population under 30, this risk appears about 5 times lower for Pfizer’s Comirnaty® vaccine compared to Moderna’s Spikevax® vaccine (100 µg) in 12-29 year olds, the age group for which the excess of cases per million is the highest (131.6 per million cases for Moderna versus 26.7 for Pfizer). These cases occurred mainly within 7 days of vaccination, more often after the second dose, and more often in men under 30. ” HAS therefore recommends, for the population aged less than 30 years and when it is available, the use of the vaccine Comirnaty® (Pfizer) whether it is a first vaccination or a booster. The vaccine Spikevax® (Moderna) can be used as a primary series (full dose of 100 µg) and for the administration of a booster dose in half-dose (50 µg) in subjects aged 30 years and over. “This is particularly interesting for people at risk of severe form of Covid-19.”
What are the differences in their side effects?
According to the monitoring point for the adverse effects of Covid vaccines published by theANSM In early December 2021, the percentage of side effects differed very slightly between the two vaccines.
| As of December 9, 2021 | Number of injections | Cases of adverse effects | % side effects | Of which severe cases |
|---|---|---|---|---|
| Pfizer-BioNTech | 90 036 800 | 75,443 | 0.08% | 26% |
| Moderna | 12,314,500 | 16 833 | 0.14% | 18% |
► Regarding the effects observed after the booster dose, the drug agency does not report “no specific signal” for both vaccines: “The profile of reported adverse reactions is similar to that reported in a comparable population seen at the start of the vaccination campaign.”
► Regarding the risk of myocarditis and pericarditis: cases of have been reported after vaccination with Comirnaty and Spikevax in Europe. These manifestations are recognized as a side effect of mRNA vaccines by the European Medicines Agency (EMA). The risk however is “higher with the Spikevax vaccine “ especially in young men under 30, after the second dose. the risk of pericarditis also appears to be more marked after the Spikevax vaccine in people under 30 years old, especially after the second dose. To date, the only hypothesis mentioned by the authorities would be the higher concentration of RNA in Spikevax (100 micrograms of RNA versus 30 micrograms in Pfizer vaccine). These new data do not to date call into question the benefit / risk ratio of vaccines against Covid-19 for the French health authorities.