Q: Since they were already hit hard once, shouldn’t they have some herd immunity?
A: Spain has seen an alarming increase in confirmed cases since mid-July, even surpassing the U.S. in daily cases per capita.
But so far, deaths have only ticked up slightly compared to the height of their epidemic in March and April (see figure).
Why might this be? The rise in cases in Spain coincided with a re-opening of the country to summer tourism, on which its economy strongly depends.
As in many countries, blame was quickly placed on the shoulders of young people partying and socializing. An enthusiastic return to nightclub venues relative to other European countries likely played a role– where poor ventilation, close contact and loud talking create a perfect recipe for transmission. Transmission clusters have also been traced to seasonal fruit workers and others living in crowded accommodations.
Once seeded in the younger populations however, spillover to older family members can happen very quickly, especially in a country with high levels of inter-generational and contact and co-residence.
Spanish epidemiologist Miguel Hernan states: “Epidemics are like fires: they can break out again due to a spark, but not all sparks cause a fire. The number of sparks in Spain is probably higher due to the spontaneity and the closeness of our personal relationships.”
Why are deaths so much lower than the previous peak?
• It’s important to remember that confirmed cases now don’t mean the same thing as confirmed cases in March and April, due to the limited testing early in the pandemic. Today’s actual case numbers are still likely much lower than the spring.
• Early increases have been driven by infections at younger ages, and vulnerable locations such as nursing homes are likely better protected.
• Even without breakthrough treatments, there has likely been significant learning and improvements in clinical care for severe COVID-19 cases.
• Hospitalizations and deaths lag new cases by several weeks, and hospitalizations are on the rise so an increase in deaths may still follow.
Death is also not the only metric of concern; emerging evidence of long-term health effects of COVID-19 infections is important to keep in mind.
What about herd immunity?
Spain is an interesting case, as some have hypothesized that hard hit areas like New York City now have very low cases because of a high level of immunity in the community. Since even previously hard-hit areas like Madrid are seeing renewed spikes in transmission in Spain, this one data point calls into question the hope that herd immunity will provide the shield against a “second wave.” This means all local areas need to remain vigilant with precautions and put out any emerging sparks as soon as they are detected.
What about the rest of Europe? France has also seen a sharp increase in cases likely due to summer tourism, while Italy and Germany seem to be managing to put out their small fires with stricter contact tracing and quarantining regimes (see figure). Just in the past two weeks, the UK (where I live) has seen a sharp increase that is leading to renewed restrictions on social gatherings of more than 6 people.
While difficult to pin down, the common denominator for increases in transmission seems to be a return to large gatherings and indoor socializing, as well as a lack of quick responses with contact tracing and quarantining for new clusters.
These “second waves” are sobering, as many of us hoped that the hard work done in lockdowns around the world and lessons learned could prevent a repeat of the high levels of infections and deaths seen early on.
The good news is thus far we have not yet seen a return to the previous high death tolls in Europe. Spain may be an extreme case rather than a foreshadowing of what is to come for the rest of Europe, but only time will tell.
Stay safe and stay sane, and stay tuned for more updates from the Nerdy Girl on the other side of the pond!
Links on rising cases in Spain: