Can the third dose be done 5 months ago? Who has covid should do it? Infectious disease specialist Roberto Cauda responds

Variant Omicron – the third dose is necessary, Serum It showed us that it is critical to reduce hospital admissions and infection-related deaths from Corona virus disease-19, explain Roberto Tell, director of the Complex Operations Unit for Infectious Diseases at the Agostino Gemelli Polyclinic. We asked him the most frequently asked questions (Instructions) on the new Omicron variant and the third dose of the vaccine.

In a scenario where the Omicron variant becomes prevalent, how important is it to take the third dose?
As for other vaccinations, let’s call them booster vaccines because they work to strengthen and reinforce the protective response. In the case of Covid-19, we have observed a gradual decrease in immunity to infection even if it is lower against serious diseases. Data collected in Israel that vaccinated its population very quickly tells us that with this third boost, immunity returns at a high speed.

The best vaccine, Moderna or Pfizer?
It’s a question they ask me a lot. The data is completely composable. There are absolutely no problems in terms of effectiveness or safety. Asymmetric 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 the vaccine even if it is not explicitly based on new variants (today we have vaccines made from the Wuhan virus: the Chinese archetype) provides good protection. But it is necessary to give the third dose to stimulate the response. Even against Omicron

Can the third dose be given? Could it be done five months ago?
Yes, the EMA occurs for a period of three months. Great Britain and South Korea advanced to three months. There are no efficacy or safety issues.

Who has recovered from Covid after having already completed the first course of vaccination, should they take the third dose?
If a person becomes infected they develop a natural immunity, so it is as if they have taken a third dose. This means that there is no need to do it quickly but that an appropriate period should pass. I repeat: it should not be done immediately, it should be done remotely if necessary.

How can a virus mutate so much and why?
When viruses reproduce, they make mistakes, mutations in their viral genome. When you include certain points in the genome, you can gain advantages. The advantage in question is that the virus is more transmissible. For example: the D614G variant traded in Italy which was then replaced by Alfa which was in turn replaced by Delta. The biological advantage is the greater contagion of the later variants.

Is Omicron more dangerous?
The advantage that each variant expresses is in terms of contagion. Never so far has one variant inflicted stronger clinical terminology than the other.

How long does it take for the third dose to work?
The answer is almost instant. What we don’t know is how long it will last: We don’t know if we’ll need periodic reminders.

What should be noted to understand how dangerous Omicron can be?
If Omicron is also going to spread in Italy, it will look at the number of infections, the number of hospitalizations and deaths. It will be important to check whether thanks to vaccinations there will be no increase in deaths or even hospitalizations in the face of a large number of infections. But it is too early to draw conclusions because we do not have the elements to do so. We need to study what our colleagues from South Africa and Britain are telling us: for now they say it is less dangerous, 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 people who are not immunized and then we have two and a half million over 50 who can have severe forms. A very positive fact is the launch of a safe childhood vaccination. In the United States, millions of children have been vaccinated with mRna vaccines and also in China with the inactivated virus: parents should take this into account. The success of this campaign will depend on how you explain its importance and the International Space Station has done an amazing job of consulting pediatricians and experts and making this information available. I have great confidence in the regulatory bodies: Ema, Aifa and FDA. If the vaccine is licensed, it is safe.

When do we know if a fourth dose is needed?
Israel is the leader in scientific research with a lot of data. He quickly vaccinated his population. This made it possible to verify the “immunity decline”, that is, the descending immunity. At that moment we discovered that the third summons was necessary. We’ll have to wait for the data for a possible fourth dose.

When do we say we are out of it?
When the virus becomes endemic and therefore no longer represents a threat. The World Health Organization has officially declared the beginning of the epidemic and will issue a decision about its end when no more Sars-Cov-2 infections are recorded anywhere in the world for 40 consecutive days. That would be the end of the epidemic. We have to look at things in a global way: we go beyond our borders, and we look at those densely populated areas of the world like Africa where there are few immunized people, and therefore there is a high risk of variables.

I am waiting for the third dose, so what should I avoid?
We must avoid injury. I also recommend wearing a mask outdoors, I avoid crowded places and gatherings and because we’re going to party, I’ll avoid a lot of dinners.

And what about the masks? Which ones do you use?
Ffp2 provides more protection: use it when you stay at home for a long time. In general, if everyone uses the surgical mask, we are protected. Let’s not forget about hand hygiene and the distance: more than a meter. Americans advise a distance of “six feet,” about 1.80 metres.

What are the most interesting research areas at the moment?
On January 9, the Chinese made available to us the sequence of the virus: thanks to that information we got the vaccines. But this is a path driven by decades of research: mRna vaccine technology dates back to the 1990s, meaning that vaccines are not experimental, and were not developed “in a hurry.” What we got was thanks to scientific research. The Covid virus has caused disasters but it has also taught many things about possible pandemics that follow. Example? Preserving the habitat of wild animals, now diminished, to prevent contact with humans. Then there is the specific scenario related to vaccines: There are the new vaccines that Valneva has developed thanks to super-tested technology and are those of inactivated Sars-Cov-2 virus (like the flu vaccine), and there is Novavax which is not a genetic vaccine but a protein vaccine. All these preparations will be especially useful for the following calls. Then there are the vaccines side that are still being tested: the inhaled (nasal spray type) or the oral vaccine. These can also activate an immune response in the upper airways in addition to the systemic response. This may be beneficial in reducing not only the risk of serious illness but also infection.

Stefania Piras