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Coronavirus: calendar, side effects, contraindications … ten questions about the vaccine

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For many experts, the Covid-19 vaccine could end the global pandemic. But many questions remain. We answer ten questions from readers to take stock.

While the race for the vaccine against the Covid-19 is more than ever scrutinized around the world, many questions are circulating. When will we receive this vaccine? Will it be necessary if one has already been contaminated? What side effects? … La Dépêche du Midi answers your questions about vaccination.

  • When can we get vaccinated?

Associated laboratories Pfizer and BionTech claim to have developed a vaccine that is 95% effective while their competitor, Moderna, claims 94.5% effectiveness for its own. However, phase 3 of the experiment is not completed for either one, said Gabriel Attal, the spokesperson for the French government.

Please understand that at this stage, no marketing authorization has been issued by the European Medicines Agency (EMA). However, the EU has just announced that the green light could be given “from the second half of December, if the procedures go smoothly”.

The orders and organization of the vaccination campaign are indeed coordinated at the continental level. Europe plans to start making vaccines available to its nationals in the first quarter of 2021, “in an optimistic scenario,” said Andrea Ammon, director of the European Center for Disease Prevention and Control.

The European Union has passed a recommendation of 300 million doses in which France has secured 90 million doses. At the rate of two injections per person, 45 million French people can therefore be treated.

  • How will the vaccination campaign be organized in France?

There won’t be doses for everyone, not for several months anyway. Most countries that are now building their future vaccine strategy will therefore prioritize access to treatment.

It is also the recommendation of the Scientific Council in France, which is aligned with a protocol struck at the corner of common sense: first of all nursing staff, by nature overexposed, then fragile people, before the extension to the general public. But questions remain unanswered: lack of knowledge about a vaccine that has never been administered, its injection will have to be done under medical supervision.

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A large-scale home vaccination campaign therefore remains to be organized for fragile and vulnerable people who cannot go to a professional …

  • In the case of the vaccines developed by Pfizer and Moderna, did the vaccinated patients who did not contract Covid-19 develop any antibodies? If so, what is the average rate?

The very principle of a vaccine is to allow the production of antibodies. This is therefore also the case here for the vaccines developed by the Pfizer and Moderna laboratories. Nevertheless, “it is still impossible to say with certainty what is the titre – that is to say the concentration – of antibodies developed”, affirms Jacques Izopet, head of the virology department of the Toulouse University Hospital. “We do not yet have sufficient data on these two vaccines to answer this question, but it is indeed a major issue, because it is the amount of antibodies produced that will determine the duration of vaccine protection in particular. “

Regarding the other vaccines under development, on the other hand, “some studies have made it possible to detect the antibodies produced, but their concentration is very difficult to assess, because it can vary depending on the techniques used”, specifies the virologist.

  • What do we know about the possible side effects following the injection of anti-Covid vaccines? Who would be responsible for serious side effects?

Here again, it is difficult to know whether serious side effects could appear in the more or less long term in vaccinated patients, for lack of necessary hindsight. “But to date, there has been no serious adverse effect in the current vaccine trials, or they have been discontinued”, specifies Jacques Izopet.

It should nevertheless be remembered that all vaccines have minor side effects, “if only small pain at the injection site”, recalls the virologist. “But so far the results of the ongoing tests are very reassuring on this point.”

In the event of serious side effects however, “it will be necessary to ensure that they are attributable to the vaccine: they could for example be the consequence of an excessive immune response, or of a particular genetic susceptibility. unfortunately, only time will tell, but I hope there won’t be ”.

  • Could there be medical contraindications that would prevent receiving the anti-Covid vaccine? If so why ?

Medical contraindications are common for vaccines, as Jacques Izopet reminds us: “Some vaccines cannot be administered to pregnant women or to immunocompromised people, for example. It depends on the types of vaccines.”

Regarding the anti-Covid vaccines developed at the moment, the answer remains the same: it is still too early to know if any contraindications will be necessary. “Once the results are published, it will be necessary to analyze all the side effects listed and to make the comparison with the people who received the vaccine and presented this type of side effects”, details the virologist.

  • Knowing that the vaccine developed by Pfizer must be stored at a maximum of – 70 ° C, how can it be injected into the body?

The medium-term storage of the vaccine must indeed be done at an extremely low temperature, “but of course, at the time of the injection, this vaccine can be taken out and thawed in order to be able to be injected”, reassures Jacques Izopet.

  • The vaccine developed by Moderna is based on the same messenger RNA technique as that of Pfizer, but can be stored at much more conventional temperatures (4 ° C, as in all refrigerators). Why such a difference ?

Just because two vaccines are developed using the same messenger RNA technique does not mean that the constraints associated with their storage should be the same. “This is because it is not just the molecule behind the vaccine that comes into play, it is also everything that is administered with it to deliver the messenger RNA under the right conditions. these are the elements that vary the conservation constraints, ”explains Jacques Izopet.

  • Will people who have already had Covid still need to be vaccinated?

The marketing authorizations have not yet been issued, of course, and it is these which will determine whether the patient’s serological status must be known before administering the vaccine, “but a priori, it is quite possible that ‘it is not necessary to know this status “, explains the Toulouse virologist. “The fact of having been exposed to Covid and of having had antibodies beforehand, will not have a deleterious effect if one receives the vaccine. There will therefore not necessarily be a PCR test before the injection. more.”

As to whether people cured of Covid still have an interest in getting vaccinated. Here again, the answer is to be used in the future: “Only time will tell, since we do not know the duration of immunity to the virus once we have produced antibodies.”

  • Is there a risk in getting vaccinated when you are sick with Covid?

In this case, “common sense suggests that there is no need to vaccinate in the situation of a patient with symptoms of Covid”, considers Jacques Izopet.

  • Can we have immunity problems with messenger RNA?

All vaccines carry a risk of “autoantibody” production. This is also the case for vaccines developed with messenger RNA. “But for now, no data allows us to confirm or deny that there would be a greater risk with this new technique,” ​​concludes the virologist.

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