德国新冠肺炎病死率为何如此之低？专家：很难说

The coronavirus contagion has impacted Europe in very different ways, and nobody is entirely sure why.

If you go by a cursory read of the numbers, Germany appears to be experiencing a less fatal outbreak than that of Italy. What jumps out is the death rate—the German rate is 0.4% compared with 9.5% in Italy. There is no shortage of theories as to why that might be.

Dig deeper into the numbers, and more stark differences appear. As Bloomberg has noted, just 18% of German cases involve people over 60 (the group most at risk) while 56% of Italian cases fall into that category. Both countries have an aging population, so it doesn’t appear to be a mere question of demographics. Italian elders are more likely to live with their children, however, so perhaps that’s why a larger proportion of them are getting sick. Or maybe it’s the fact that Germany carried out widespread testing and containment from the early stage of its epidemic.

It appears that young Germans returning from their holiday have sparked the outbreak in that country. Maybe, as German virologist Christian Drosten has suggested, the Italian figures are skewed because they miss a lot of infected but asymptomatic young people who never felt the need to go to the hospital, where most of the Italian testing takes place. As the Guardian has pointed out, Italy is also conducting more widespread testing of the dead than Germany does, which could partially explain the disparity.

Don’t forget to throw into the mix the fact that Germany’s outbreak apparently began weeks after Italy’s, so its health care system is a lot less overwhelmed for now, making it easier to keep COVID-19 sufferers alive.

This is a dizzying array of potential factors. So what conclusions should be drawn at this point? This is where the experts urge a lot of caution, and stress that this pandemic is only in its early stages.

“I think we will have a clear understanding of the situation when it is all over. The numbers and counts are made at the end,” Giovanni Maga, professor of molecular biology at the University of Pavia, Italy, told Fortune.

Lothar Wieler, president of Berlin’s Robert Koch Institute—which is taking the lead on coronavirus statistics-gathering in Germany—also said it was far too soon to analyze the figures definitively. “We are at the beginning of the epidemic, and the number is growing,” he said at a Wednesday press conference, adding that it is “open-ended how this epidemic will develop” in Germany.

Is it a major problem that different countries use disparate methods for tabulating coronavirus infections and deaths? Not really, said Lauren Gardner, the civil and systems engineering professor who leads the team behind Johns Hopkins University’s much-cited dashboard showing COVID-19 cases around the world.

“The varied reporting generally does not impact policy, as the discrepancies in reporting are only temporary, and simply due to varying update frequencies across sources,” Gardner said in an emailed statement. “Over time, the reports align, and the policymakers are aware of this.”

Gardner said many U.S. states and other countries are improving their reporting mechanisms to publish accurate coronavirus counts more quickly. “As these come online, and prove accurate, we will incorporate them directly into our reporting system, so we expect the consistency to improve moving forward,” she said.

A spokesperson for the European Centre for Disease Prevention and Control also pushed back against the idea that countries’ different testing approaches—such as those in Germany and Italy—are problematic when trying to judge the relative scale and impact of the outbreak.

“It is normal that some variations in implementation of such case definitions happen on national and subnational levels,” the spokesperson said. “Detailed surveillance is challenging in such rapidly evolving epidemic situations.”