Stefania Salmaso
“We are well advanced, it is crucial to reduce outbreaks in the workplace”
Herd immunity is not black or white, but a gray scale, explains Stefania Salmaso, former director of the National Health Surveillance and Promotion Center of the Higher Institute of Health and expert of the Italian Association of Epidemiology.
And what tonality have we arrived at?
«We are at a good point. Let’s consider what we’ve always asked for vaccines: to prevent serious cases and deaths. In this, the steps forward are great, even if there are unknowns: possible variants, the duration of immunity, winter. We are missing another step to be more reassured: we should reach 90% of the immunized and the completion of the third doses for those who need it. Portugal, which is sailing towards this threshold, has managed to reopen the country while maintaining a very low impact ».
In places where the Green Pass is asked for, can immunity be said to reach 100%?
«No, also because vaccines do not prevent infection 100%. However, it would be useful, to further increase vaccination coverage and consent for the Green Pass, to raise awareness of the risk of contagion in the workplace. For example, many outbreaks have spread to the agri-food sector, such as in a large fruit and vegetable center in the south, or in a meat processing plant in the Trento area. Here the low temperature favored the virus. Another risk factor is noisy places, where you are forced to scream and emit large quantities of droplets. Logistics was also particularly affected – many outbreaks have spread among couriers – especially where the chain of contracts and subcontracts makes controls more difficult ».
Carlo La Vecchia
“The third dose will defend the population from the return of the virus”
“Those who want to protect themselves better get vaccinated.” The message of Carlo La Vecchia, an epidemiologist at the University of Milan, is that trusting herd immunity is good, but not trusting is better. “And never with the Delta variant anyway.”
Do you expect a new wave?
“No, at least not in the next 1-2 months. We will have an increase in swabs among the unvaccinated, and this will push the cases up a bit in the next few days. But I don’t expect a resumption of serious cases and deaths ».
Because?
“Despite the visibility of no vaxes, we are among the countries that have vaccinated the most in the world. We also had widespread circulation of the virus. The immune is probably more than we count ”.
The numbers of the epidemic here are limited, but deaths remain high compared to other countries. Because?
«The infections in Italy are underestimated. I believe that in reality the currently positives are three times the official ones. In Great Britain, do-it-yourself tampons are also used, in some cases sent home, and there the official infections are about 15 times more. However, deaths are just over a hundred a day compared to our 35, where a year ago there were more than a thousand. Vaccines work for this, there is no doubt ».
Beyond the one or two months of calm, what does it foresee?
“In Israel we have seen that Pfizer’s effectiveness diminishes after a few months. Combined with the cold, this drop in immunity could put us in trouble too, who left about two and a half months after Israel. It is necessary to advance with the third doses at least for the elderly and adults, without closing the hubs “.
Giovanna Maga
“The indoor masks have protected us, we continue to wear them”
“Herd immunity is a bad translation. I would prefer group or population immunity ”begins Giovanni Maga, director of the Institute of Molecular Genetics of the Cnr of Pavia.
But are we at this goal?
“No, we can’t be there, with an infectious variant like the Delta. In fact, group immunity is a number calculated by an algorithm that depends on the infectivity rate of the virus. To achieve it we should reach 90% of the vaccinated among the entire population, not just those over 12 years old. We could only think about it if we have a vaccine for children too ».
But our situation is better than in other countries. Because?
“This is true, and even if technically we are not at group immunity, I would not make a myth of this concept. Thanks to vaccines, we have erected a remarkable barrier against the virus. Compared to the autumn wave of 2020 we have one twentieth of the deaths. The occupancy of beds in the medical area is currently 4-5%. A year ago it was ten times that. But let’s not delude ourselves, we are not out of it yet ».
What are we missing?
“Vaccinate the rest of the world, as we have done with the diseases that we have almost eradicated, smallpox and polio.”
And in the meantime?
«We do not underestimate the importance of masks. They remain decisive, especially in closed places. In Great Britain, the latest increase in infections was certainly caused by the abandonment of preventive measures. In this we have been more cautious ».
Sergio Abrignani
“Covid is now less lethal, but a worldwide campaign is needed to win it”
“We are around 3,000 official cases a day, but let’s assume that the real ones are double. We have reopened the country, the economy has restarted, the school has resumed for more than a month and the pandemic remains under control ». The wall of immunity in our country works, is convinced Sergio Abrignani, immunologist at the University of Milan.
But are we or are we not with herd immunity?
“We can’t technically call it herd immunity, but today we have good control of the situation.”
What are we missing to reach the finish line?
“It’s hard to cut it, with vaccines that don’t completely prevent infections and such a contagious Delta. Its replication index is estimated between 6 and 8, whereas the Wuhan strain was between 2 and 2.5 and the alpha, which was widespread in Italy until June, was between 3.5 and 4. Our goal is actually it has always been another: limiting the lethality of Covid ».
But it is never low enough.
“We have reached the levels of influenza, which in a normal winter causes 3-6 million cases and 3-10 thousand deaths to be counted, among the same fragile people who are at risk for Covid”.
Will the immunity given by vaccines fade over time? Will we lose ground as the months go by?
«We have to move forward with the third doses, and without hesitation, because almost all types of vaccines work with three doses. And we also need to immunize the rest of the world. Thinking selfishly, we cannot think of defeating the pandemic without involving other countries in the vaccination as well ”.
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