Yesterday, the Ministry of Health and the autonomous communities agreed start putting a souvenir dose (with Pfizer or Moderna) to the two million people who during the vaccination campaign were vaccinated with Janssen serum. This second dose will begin to be put on November 15.
What, according to various media, the decision has been “adopted after verifying the lower effectiveness of the single-dose serum”, it is worth asking:what happened to this vaccine And, above all, why this rush when it comes to putting the booster dose?
What happened to Janssen?
The answer is simple: nothing has happened. From the first moment we knew that the Janssen vaccine was a single dose only on paper. The injectable used the same technology as the AstraZeneca vaccine and had numbers very similar to it. What happened is that, with a great “business sense”, Janssen saw that the data from the first injection allowed “selling” his product as a single dose to regulators and governments.
It was especially interesting in a context of vaccine shortages and the need to achieve high vaccination numbers. But in essence it is something very similar to what the United Kingdom did delaying the second shot of AstraZeneca as much as possible: we all knew that the second dose was going to arrive sooner or later. In fact, Janssen was running a clinical trial with two injections in case the results of the first did not allow approval as a single dose.
So why not get the booster fix with Janssen? If we remember, we will remember that the debate about whether it was better to use the same vaccine or another it was already had with AstraZeneca in summer. Now we have more information about the safety of mixing vaccines, it is true; but deep down the explanation of why to use Pfizer or Moderna is very simple: we don’t have Janssen for everyone because many contracts were canceled and we have plenty of RNA vaccines.