Rapid authorization, to prevent the risk of shortages.
The European Medicines Agency (EMA) authorized on Friday a new technique for injecting the vaccine against monkeypox, which will make it possible to immunize more people with a lower dose.
This injection technique, intradermally, could thus prevent shortages of vaccine doses, while the virus is spreading in Europe and the United States.
Explanations.
How it works ?
Intradermal injection allows a small dose of vaccine to be administered just under the upper layer of the skin, less deeply than subcutaneous vaccination, which is known for example for vaccination against measles, or intramuscular injections, as when vaccinating against Covid-19.
As shown in a training video from the US Centers for Disease Control and Prevention, the needle of the syringe injecting the vaccine by this means is inserted slightly horizontally, only a few millimeters into the skin, to penetrate the solution between two layers of skin.
In 2011, an article in the bulletin of the World Health Organization already mentioned a “renewed interest” in this method of vaccination, due to the strong presence of “antigen-presenting cells” in the dermis and epidermis.
For some vaccines, "this suggests that administering doses between these layers of skin, compared to intramuscular or subcutaneous administration, should be more effective and produce an immune response with lower amounts of antigen vaccines" , write the researchers of the study, who underlined however that the subject deserved to be studied more.
Is intradermal injection effective?
Yes, according to the European Medicines Agency, which is based on a study carried out by its emergency task force.
In its clinical trial involving around 500 adults, the group found that people who received one-fifth (0.1ml) of the subcutaneous dose (0.5ml) of the vaccine intradermally "produced levels of antibodies similar to those of people who received the higher subcutaneous dose”.
The vaccine administered was the Imvanex vaccine, designed by the Danish group Bavarian Nordic, originally approved to fight smallpox and also very effective against monkeypox, which is less virulent.
"The exact level of protection and the duration of protection provided by the vaccine (administered subcutaneously or intradermally) remains unknown", however indicates the EMA.
As the clinical trial was carried out on healthy people, the Agency is also unable to determine whether the immune response of the intradermal injection would be as strong in immunocompromised or HIV-affected patients.
Regarding side effects, intradermal injection may cause a "higher risk of moderate local reactions": 94.8% of patients injected intradermally experienced redness and thickening of the skin, compared to 58, 1% for those injected subcutaneously.
The study emphasizes that no “severe and negative” event linked to intradermal vaccination was observed.
Why this authorization now?
The EMA authorized this method of injection to meet the growing demand for doses on the continent, the Imvanex vaccine being the only one authorized against monkeypox and its stocks being limited.
With intradermal vaccination, which requires a fraction of a subcutaneous vaccination dose, the number of doses available is multiplied by five.
VIDEO.
Monkey pox vaccine: “extremely strong” demand in Paris
"National authorities may decide, as a temporary measure, to use Imvanex by intradermal injection at a lower dose to protect those at risk during the current outbreak of monkeypox, as long as the vaccine supply remains limited,” concluded the EMA.
Has this method been used before?
This type of vaccination has already been authorized for several vaccines, in particular BCG (against tuberculosis), the influenza virus (from the flu), as well as rabies, underlines the EMA.
Intradermal vaccination has already been authorized since August 9 in the United States, where the Food and Drug Administration, the American drug regulatory authority, authorized this type of injection under conditions similar to those of the EMA.
The objective is the same as in Europe: to increase the number of doses available to limit shortages.
The FDA referred to a 2015 study of the Jynneos vaccine (the American name of Imvanex), again demonstrating that an intradermal injection caused "an immune response similar to subcutaneous administration".
The study highlighted side effects such as "redness, thickening, itching and swelling" at the bites, which remained bearable.
Are we going to carry out intradermal injections in France?
We have to wait for the opinion of the National Agency for the Safety of Medicines (ANSM) on the question to find out.
In the event that it validates this type of injection, it would also be necessary to have health professionals already familiar with intradermal vaccination, as recommended by the EMA in its press release.
"Changing the administration of a vaccine dose is not a light task," warned several researchers in 2011 in an article in the WHO bulletin studying intradermal vaccination.
To carry out this type of vaccination at reduced doses, it is necessary in particular to adapt the vaccination equipment, or even change the formats of the vials to minimize the risk of waste, they underlined.
Read alsoMonkey pox: "I was screaming alone at home" ... after 21 days of isolation, Killian still has symptoms
There is also the question of vaccination schedules.
The EMA study treated healthy patients, with two doses given intradermally four weeks apart.
But in France, the first doses of Imvanex vaccine have already been administered subcutaneously, and the administration of second doses has been postponed for some of the patients in order to cover a maximum of the population with at least one dose.
Could we then give a second dose intradermally to these primary-vaccinated patients?
Asked about this this Saturday by Le Parisien, the ANSM had not yet responded to our request in the middle of the afternoon.