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ROME — In the northern city of Bergamo, Italy’s hardest-hit area in the first wave of the coronavirus pandemic, the significant proportion of residents who have already been infected with the virus might be the very thing protecting them from a repeat medical catastrophe.
In the spring, the city became a grim national symbol of the tragedy unfolding in Italy, and later across Europe. Its cemeteries overflowed, and army trucks were forced to haul coffins to other regions. So far, some 3,000 people have died of COVID-19 in the city.
Now, as the country grapples with a worsening second wave of the virus, Bergamo appears to have escaped a similar fate, despite the fact that the wider region of Lombardy has emerged as a hot-spot for the virus once again.
Some doctors have acknowledged that the lower numbers of cases could be partially attributable to more cautious behavior by residents, saying the brutal experience of the first wave may have made them more attentive to anti-coronavirus measures such as social distancing.
But several experts suggest the low figures point to a degree of “community immunity” that has reduced the risk of new outbreaks. Chief anesthetist at the Bergamo’s main hospital, Luca Lorini, hailed it as a “natural vaccine.”
A much higher percentage of the inhabitants of Bergamo province have developed some resistance to the virus since the spring, compared to Lombardy and Italy as a whole. Some 57 percent of 10,000 people tested in June by the provincial health authority were found to have antibodies. Although these tests were mostly conducted in the worst-affected areas of the province, a more representative study, published by the statistics agency ISTAT and Italy’s health ministry, showed that one in four residents of Bergamo province were found to have antibodies — compared with 1 in 13 residents in the province of Milan and one in 40 in Italy as a whole.
As many as 420,000 people may have been exposed to the virus in Bergamo, according to projections by the Mario Negri Institute for Pharmacological Research in Bergamo, which found that 96 percent of infections could have gone undetected by health authorities.
According to experts, that data explains why Bergamo has remained relatively untouched in the second wave, whereas cities and towns that were less affected in the spring — such as Milan and Como — have seen major outbreaks.
Between October 2 and 23, for example, cases of COVID-19 increased only 7 percent in Bergamo, compared to the rest of Lombardy where they increased by as much as 65 percent. Over the past week, the province of Bergamo had an average of 20.4 new cases a day per 100,000 people, compared to 81.4 in the province of Milan.
People who were exposed to the virus in the first wave are likely to have antibodies that protected them from getting ill during the second, said Massimo Galli, an expert in infectious diseases at the University of Milan.
Although antibodies do not always offer full protection — there are several cases of people being re-infected with a different strain of the virus — “generally, community immunity counts a lot for a virus like this,” Galli said in an online meeting with journalists.
“I am confident that the great majority of people that have had virus are protected from this infection or if they get a different strain, they will have a mild infection.”
Bergamo is not the only former hot-spot to now be spared another major wave of infections. Across Lombardy, the provinces that suffered the highest number of deaths in the spring now appear to be less affected. Brescia and Cremona, for example, are registering some of the lowest numbers of new infections in the past weeks.
“The correlation is very, very significant,” said Giuseppe Remuzzi, a professor and director of the Mario Negri Institute, which carried out its own antibody tests. “In northern areas where it circulated [in the spring], the virus can’t find people to infect.”
It may be that “in Bergamo people are more afraid and therefore follow the restrictions more closely,” he acknowledged, but he dismissed the idea that this could be a decisive factor: “I am not convinced that this is the explanation, as I think the behavior across Lombardy is quite homogenous.”
There is now a “degree of natural immunity, community immunity,” he said, adding that he preferred not use the term “herd immunity,” which is typically defined at between 50 percent and 90 percent of the population depending the infectiousness of the disease.
“We are still a long way away from that,” he added.
Others say a lower percentage of immune residents could already significantly help slow the spread of the virus.
“We know that when the reproductive rate of the virus is over 1, then cases increase exponentially,” said Luca Foresti, a physicist and CEO of the Centro Medico Agostino, a group of clinics.
“If it is not much above 1, even 15 to 25 percent of people with antibodies can be enough to send [the reproductive rate of the virus] under 1 and make the number of new cases to decrease exponentially,” he said. “This small difference can make a big difference in a few days … I call it small herd immunity.”
With an eye on the looming economic catastrophe from successive lockdowns, some are hoping that so-called community immunity can help them make the case for relaxing coronavirus restrictions and further open up the economy.
Local MP Stefano Benigni, who is not affiliated to any party, wrote to Health Minister Roberto Speranza and the governor of Lombardy, Attilio Fontana, earlier this month saying that it was a “mistake” to “unfairly penalize areas [such as Bergamo] where people are not experiencing serious problems.”
But such a decision, even if technically sensible, could be politically problematic.
It is “much easier” to keep restrictions the same across an entire region than to differentiate between them, according to Foresti. “It is like saying that over 65-year-olds should stay home, or that those with antibodies can go outside. These ideas are not technically wrong but politically complicated.”
Lombardy's scientific committee is “considering loosening restrictions in areas such as Bergamo … if it doesn’t make the situation worse or damage the rest of the region,” Fontana, the governor, told POLITICO.
For now, most Bergamo residents are unlikely to feel that the catastrophe earlier this year was worth the relatively easier ride they are now experiencing. Many are still mourning lost family members or struggling to keep businesses afloat, even if they haven’t had to endure another medical emergency of the kind that saw hospitals overflow in March and April.
Besides, the reprieve may only be temporary, as scientists are not sure how long the beneficial effects of community immunity could last.
“What we know is that it lasts for six months,” said Foresti. “Whether it lasts for two or three years, we will have to wait until we get there.”
This article is part of POLITICO’s premium policy service: Pro Health Care. From drug pricing, EMA, vaccines, pharma and more, our specialized journalists keep you on top of the topics driving the health care policy agenda. Email [email protected] for a complimentary trial.