The elusive footprint of contagions

There is no country that can contain an epidemic if it does not know where its patients are infected.

It is told by the manuals on the history of medicine and is recalled these days by specialists who fight against the coronavirus in Spain.

“Many patients come to us unrelated to an outbreak.

They are isolated cases, with no clear relationship with others ”, explains Santiago Moreno, head of infectious diseases at Hospital Ramón y Cajal (Madrid).

“Most of the cases come from family environments and, to a lesser extent, from social gatherings.

But in a relevant percentage it is not possible to know the primary source of the infection ”, adds Benito Almirante, who holds the same position at the Vall d'Hebron Hospital (Barcelona).

According to the latest report from the National Epidemiological Surveillance Network (Renave), dated last day 9, in 39% of the cases diagnosed in Spain since May 10 the origin of the infection is "unknown", while in a An additional 31% contagion has occurred in the home environment.

The following categories are "others" (15%), "work" (8%) and health and social health centers, which add up to 6%.

They are the broad traces of the origin of the infections, to which health workers try to give more precision in their daily activity, although they regret that insufficient contact tracing and the poor quality of the data produced by the system continues to weigh down the fight against virus.

José Miguel Cisneros, head of infectious diseases at the Virgen del Rocío hospital (Seville), and Manuel Rodríguez Iglesias, head of microbiology at the Puerta del Mar hospital (Cádiz), agree that contagions grow where the measures are relaxed.

“At social and family gatherings we tend to feel more secure.

The fear of contagion is attenuated or even disappears and security measures are breached ”, summarizes Cisneros.

"In the family and social environment, prevention is relaxed by not suspecting that you are infected," adds Rodríguez Iglesias.

Joan Ramon Villalbí, from the Spanish Society of Public Health and Health Administration (SESPAS), specifies that behind the heading “domiciliary” —the second in importance in the Renave report— very different realities are hidden, which makes the

even more precise

of contagions.

In some cases, infections are the second link in a chain that started elsewhere (workplace, parties and bottles ...).

In others, they are outbreaks arising from meetings with the extended family.

And “there are also neighborhoods where people who are not a nuclear family often live together.

And this has proven to be very important, because it is in these areas with a disadvantaged socioeconomic profile where the most intense transmission chains have developed ”, he adds.

Pere Godoy, president of the Spanish Epidemiology Society (SEE), recalls that after the end of the state of alarm at the end of June, the virus circulated mainly in the health field and in sectors that, such as the food industry, did not stop their activity.

From there, the virus spread to younger and more socially active groups, and then to the family environment.

“Now, in addition, the virus has greatly increased its incidence in tourist areas.

The Balearic Islands, the Canary Islands, the Mediterranean coast and Cerdanya [in the Catalan Pyrenees] have seen the cases grow a lot, ”says Godoy.

The president of the SEE warns of the challenge that, "with the current levels of virus circulation, means the reopening of schools."

Elisabet P. is 18 years old and studies engineering in Barcelona.

At the end of August she met "with nine other friends" in a family home of one of them in a town in La Cerdanya.

“We didn't do anything special.

We listen to music, have a drink and talk, ”he says.

They do not know who the index case was, only that on the 31st Elisabet and another assistant began to feel ill.

“I was short of breath, I had a cough, a high fever.

In the end, all but one of us tested positive, although most without symptoms, "he says.

His case is considered by the experts consulted as "a good example" of one of the most common forms of spread of the virus that occurred this summer.

But, again, the available data prevents an overall picture from being made.

There are huge differences between communities - in Andalusia and Madrid, for example, the origin of 80% of infections is unknown, a percentage that drops to about 30% in Murcia and the Basque Country, according to Renave -, which largely fragments stage.

The Ministry of Health and the communities agreed a month ago measures to stop the second wave, including putting an end to nightlife.

Since then, through ups and downs and partial confinements, several regions have been tightening the measures.

One of the last to do so has been Murcia, which agreed on the 3rd "the abolition of the bar and window service in hotels and restaurants" because they are areas with the highest risk of contagion.

Experts do not dispute the timing of these measures, but they miss "greater coordination in the face of the second rebound of the virus," concludes Villalbí.

Spain only tracks three contacts for positive

Poor contact tracing doesn't help improve the situation either.

According to the Renave report, the median of close contacts found per positive case in Spain is just three.

"It is insufficient and reveals that in most cases, the contacts of the most intimate circle, such as people who share a home, are barely reached," Godoy laments.

"The desirable thing would be to get closer to the ten contacts per case," adds Villalbí.

Godoy proposes moving towards a model, already started in some areas, in which when the PCR test is done, the patient is already discharged and the contact list begins.

"It would have a huge impact and would greatly shorten the deadlines, since you prevent the potential case from continuing to transmit the virus and in case of a positive result you can deactivate the contacts immediately."

Information about the coronavirus

- Here you can follow the last hour on the evolution of the pandemic

- This is how the coronavirus curve evolves in Spain and in each autonomy

- Download the tracking application for Spain

- Search engine: The new normal by municipalities

- Guide to action against the disease