Covid Vaccine: What Is The Difference Between Pfizer And Moderna?

By the time you booked your third dose of Covid vaccine, you may have discovered that you will not receive the same vaccine as before. Can you combine the Pfizer and Moderna vaccines? Are there any differences between the vaccines from these two companies? Here's how it works.

Why do I need a booster shot?

Because of the Delta variant and the Omicron variant which is worrying the whole world, the 5th epidemic wave has arrived in France.

To deal with the spike in cases, authorities have called on the French to get a booster dose, more commonly known as the Third dose of vaccine, to maintain the benefit of their health pass.

As the French rush to make appointments at vaccination centers, some are worried about receiving a different vaccine than their first two doses.

Indeed, many vaccination centers now offer the Moderna vaccine, while most French people have previously been vaccinated with the Pfizer.

Why are vaccination centres using the Moderna vaccine?

Perhaps you are one of the many French people who went to the vaccination centres to keep a valid health pass.

In most centers, you then discovered that only Moderna doses were offered to the over 30s.

The reason for this change is simple: France currently has a larger stock of Moderna than Pfizer.

Although the situation should be reversed soon according to health authorities, vaccination centres are reserving Pfizer doses for the under 30s for the time being.

Are the two vaccines equally effective?

Health Minister Olivier Véran sought to reassure, saying 'Moderna and Pfizer, it's the same. The only difference is that if you are under 30, we prefer to give you Pfizer and it is not for reasons of effectiveness.'

In fact, both Pfizer-BioNTech and Moderna vaccines are based on the same technology: messenger RNA vaccines.

These two vaccines are therefore compatible and have the same efficacy in preventing Covid-related infection, hospitalizations, and deaths.

The Moderna vaccine is simply discouraged for those under 30 by the High Authority for Health due to very rare cases of myocarditis.

Are there any differences between the two?

The only difference between the Pfizer and Moderna vaccines is the dosage: the two initial doses of Moderna contain 100 micrograms of messenger RNA versus 30 for the Pfizer.

This explains why more antibodies are produced with Moderna and why there is a bit more risk of adverse events in people under 30.

This is also why only half a dose of Moderna is given as part of the booster vaccination or Third dose following the recommendations of Alain Fischer, the chairman of the Conseil d'orientation de la stratégie vaccinale.

This rebalances the Moderna dosage to only 50 micrograms of messenger RNA per vaccine.

According to a study published in the United Kingdom, even with a lower dose, the Moderna vaccine is still very close to Pfizer's effectiveness.

Is it risky to mix vaccines?

Many French people are wondering if there is any risk in switching from Pfizer vaccine to Moderna vaccine. But, in fact, this mixing is rather encouraged by the health authorities.

Indeed, European health authorities have observed that, in some cases, mixing the two vaccines results in a stronger immune response.

For the same reason, it is also possible (and even desirable) to combine viral vector vaccines such as AstraZeneca with messenger RNA vaccines.

This results in good antibody levels and a higher T cell response than using the same vaccine.

To finish reassuring you, know that you will get an immune system boost regardless of which vaccine you use for your booster dose.

That's the conclusion reached by a study of nearly 3,500 people conducted by British researchers and published in the Lancet on December 2.