Variante Omicron – The third dose is necessary, the vaccine showed us that it is crucial to decrease hospitalizations and deaths linked to infections from Covid-19, explains Roberto Tail, director of the complex operating unit of infectious diseases of the Agostino Gemelli polyclinic. We asked him the most frequently asked questions (FAQ) on the new Omicron variant and the third dose of vaccine.
In a scenario where the Omicron variant will become prevalent, how important is it to take the third dose?
As for other vaccinations: let’s call it a booster because it serves to reinforce and consolidate the protective response. In the case of Covid 19, we observed a progressive decrease in immunity against infection even if less against serious disease. The data collected in Israel that has vaccinated its population very quickly tells us that with this third booster immunity quickly returns to high.
Better the Moderna or Pfizer vaccine?
It’s a question they ask me frequently. The data are absolutely superimposable. There are no problems whatsoever in terms of efficacy or safety. Heterologous vaccination is also safe: I mean people who were given AstraZeneca and Johnson during the first round of vaccination.
But does the third dose respond to the Omicron variant?
We have data from Israel and the United States: the third dose of vaccine even if not expressly built on the new variants (today we have vaccines made on the Wuhan virus: the Chinese archetype) provides good protection. But it is necessary to administer the third dose to potentiate the response. Even against Omicron
Can the third dose be brought forward? Can it be done before five months?
Yes. The EMA spoke for a three month interval. Great Britain and South Korea have advanced to three months. There are no problems of efficacy or safety.
Who has recovered from Covid after having already completed the first vaccination course, must take the third dose?
If a person has had the infection they develop natural immunity, and therefore it is as if they had taken a third dose. This means that there is no need to do it quickly but a suitable period must pass. I repeat: it should not be done immediately, it should be done remotely if necessary.
How could the virus mutate so much and why?
Viruses when they replicate make mistakes, mutations in their viral genome. When they involve certain points in the genome they can acquire advantages. The advantage in question is that the virus is more transmissible. For example: the D614G variant circulated in Italy which was then supplanted by Alfa which in turn was supplanted by Delta. The biological advantage is the greater contagiousness of the subsequent variants.
Is Omicron more dangerous?
The advantage that each variant expresses is in terms of contagiousness. It has never happened to date that one variant leads to an infection in clinical terms that is stronger than the others.
How long does it take for the third dose to work?
The answer is almost immediate. What we don’t know is how long it lasts: we don’t know if we will need periodic reminders.
What must be observed to understand the degree of severity that Omicron can entail?
If Omicron will also circulate in Italy, it will look at the number of infections, the number of hospitalizations and deaths. It will be important to verify whether thanks to vaccines there will not be an increase in deaths or even hospitalizations in the face of even a high number of infections. But it is very premature to draw conclusions because we have no elements to do so. We need to study what our South African and British colleagues tell us: at the moment they say it is less serious but it is a fact that must be taken with caution.
How is the situation in Italy?
In Italy there are 6 and a half million unvaccinated people and then we have 2 and a half million over 50 who could have severe forms. A very positive fact is the launch of pediatric vaccination which is safe. In the United States, millions of children have been vaccinated with mRna vaccines and also in China with inactivated virus: parents must consider this. The success of this campaign will depend on how you explain its importance and the ISS has done a great job consulting pediatricians and experts and making this information available. I have a lot of confidence in the control bodies: Ema, Aifa and Fda. If the vaccine has been licensed, it is safe.
When will we know if a fourth dose is needed?
Israel has led the way in scientific research with a lot of data. He vaccinated his population quickly. Thus it allowed to verify the “waning immunity” that is the descending immunity. At that moment we discovered that the third recall was necessary. We have to wait for the data for a possible fourth dose.
When can we say we’re out of it?
When the virus becomes endemic and therefore no longer represents a danger. WHO has officially declared the beginning of the pandemic and will decree its end when no more Sars-Cov-2 infections will be recorded anywhere in the world for 40 consecutive days. That will be the end of the pandemic. We have to look at things in a global way: we go beyond our borders, we look at those very populated areas of the world such as Africa where there are few vaccinated people and therefore there is a high risk of variants.
I am waiting for the third dose what should I avoid?
We must avoid getting infected. I also recommend wearing a mask outdoors, I would avoid crowded places, gatherings and since we are going to meet the parties I would avoid too many dinners.
And the masks? Which ones to use?
The Ffp2 protects more: use it when you stay indoors for a long time. In general, if everyone uses the surgical mask we are protected. Let’s not forget hand hygiene and distance: more than a meter. Americans recommend a distance of “six feet” which is about 1.80 meters.
What are the most interesting research fields at the moment?
on January 9, the Chinese made the sequences of the virus available to us: thanks to that information we had the vaccines. But it is a path driven by decades of research: the technology of the mRna vaccine dates back to the 90s. This is to say that vaccines are not experimental, they were not developed “in a rush”. What we got was thanks to scientific research. Covid has caused disasters but has also taught many things about the next, possible pandemics. An example? Preserve the habitat of wild animals, which has now shrunk, to prevent contact with humans. Then there is a specific scenario related to vaccines: there are the new ones, Valneva developed thanks to an ultra-tested technology which is that of the inactivated Sars-Cov-2 virus (like the flu vaccine), there is the Novavax which it is not a gene vaccine but a protein one. All these preparations will be especially useful for the next calls. And then there is the side of vaccines that are still being tested: the inhalation one (nasal spray type) or the oral one. These could also activate an immune response in the upper airways in addition to the systemic response. This could prove useful in reducing not only the risk of serious illness but also of infection.
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