Monday, November 29

Five great enigmas of the coronavirus still to be solved | Science



Science has never investigated anything with the same intensity as the new coronavirus. The scientific community has published nearly 350,000 studies on the pathogen, according to the British company Digital Science. However, very important questions remain to be resolved after a year of pandemic. Half a dozen experts talk about five of the main riddles.

How did the coronavirus reach humans?

It is not yet known how the new coronavirus reached the Wuhan live animal market. The Danish scientist Peter Ben Embarek, head of the mission of the World Health Organization sent to China to investigate the origin of the pandemic, said on February 9 that it is “Extremely unlikely” that the virus came out of a laboratory. This committee of experts works with the main hypothesis that the coronavirus originated in bats and passed to humans through an intermediate animal species, perhaps one of those that are crowded in Chinese fur farms. Other researchers, such as the French virologist Etienne Decroly, they are more skeptical. “Several hypotheses are still possible —zoonosis, laboratory accident, etc.— and must be thoroughly investigated,” says the expert from the University of Aix-Marseille.

Decroly is one of the 26 signatories of an open letter sent to newspapers around the world, including EL PAÍS, to demand “a complete and unrestricted international forensic investigation” into the origin of the virus. The authors recall the opacity of the Chinese dictatorship and ask to consider “all possible scenarios”, including the hypothetical infection of a laboratory worker when handling animal samples. The Wuhan Institute of Virology it is 14 kilometers away of the market identified as the initial focus, but there is no evidence that the virus came out of this scientific institution. Argentine doctor Fernando Polack, leader of two of the most important trials of Pfizer’s vaccine, calls for measures to reduce the risk of future pandemics. “How is the world going to regulate the health situation of animal food markets that represent a latent risk for the repetition of these events?”

How long will vaccine protection last?

The best news about the pandemic is that vaccines prevent practically 100% of severe cases of covid, but there are still many unknowns, as explained by virologist Isabel Sola. “We do not yet know how long immunity will last, both natural [producida tras superar la covid] such as that induced by vaccines. Nor do we know how powerful this immunity is and if it protects completely from infection or only from disease, “says Sola, co-director of an experimental vaccine against covid at the National Center for Biotechnology (CNB-CSIC), in Madrid. If current injections do not prevent asymptomatic infections, those vaccinated should continue to wear a mask in the presence of unvaccinated people, to avoid possible infections. There are multitudes of ongoing studies to investigate this aspect and some preliminary results They already suggest that vaccines will also prevent a large part of silent infections. Isabel Sola points out three possible scenarios, depending on the human immune response: that the vaccines already available are sufficient, that it is necessary to be vaccinated every year or that it is necessary to develop new vaccines that prevent asymptomatic infections, in addition to avoiding severe cases of covid.

Will variants of the virus make the pandemic worse?

The coronavirus does not stop mutating. The out-of-control growth of the pandemic has facilitated the emergence of new versions of the virus that partially escape human defenses – such as the variants detected in South Africa and Brazil – or that are even more lethal, such as the one observed for the first time in the United Kingdom. and already present in a hundred countries. The Spanish pathologist Elisabet Pujadas stresses that one of the main unknowns on the table is the effectiveness of vaccines against these emerging variants. Pujadas, a researcher at the Icahn School of Medicine at Mount Sinai Hospital in New York, believes it “very possible” that it is necessary to periodically redesign vaccines, as is already done with flu vaccines.

Why do some infected die and others don’t even know about it?

The virus killed about 1% of those infected in Spain outside of nursing homes, according to a study by the National Epidemiology Center with data from the first wave. The fatality of the coronavirus in men older than 80 years reached 12%, more than double that in women. Another of the big unanswered questions, in the opinion of the virologist Isabel Sola, is why the virus kills some people and others do not even know that they are infected. The pathologist Elisabet Pujadas agrees: “In the most serious cases we see exaggerated immune responses and hypercoagulability [un mayor riesgo de coágulos en la sangre]. We need to understand what is happening at the molecular level to develop more effective and personalized treatments. “

The Venezuelan doctor Alberto Paniz Mondolfi affects another enigma: a very minority percentage of infected children – 0.02% of the cases registered in those under 18 years of age in Spain – have suffered a strange serious disease associated with the coronavirus and known as pediatric multisystem inflammatory syndrome or MIS-C. “Deciphering the causal determinants of this condition is one of the most important debts we have in the study of covid,” says Paniz Mondolfi, also from Mount Sinai Hospital in New York. The syndrome has affected more than 2,600 children in the United States, 66% of them Hispanic or Black, and has killed 33, according to US health authorities.

What will the future look like after the pandemic?

This is one of the most important unknowns. Doctor Alberto Paniz Mondolfi recalls that four other types of coronavirus, now linked to the common cold in the winter season, also jumped from animals to humans in the past. “It is possible that in the future the covid will be an infection of habitual occurrence, with possible outbreaks probably associated with the seasons”, reflects the Venezuelan researcher.

Paniz Mondolfi gives the example of the last great pandemic of the 19th century, the so-called Russian flu of the years 1889 and 1890. The team of the Belgian virologist Marc Van Ranst suggested in 2005 that the culprit of that pandemic was not a flu virus, but a coronavirus, the OC43, today basically harmless. “If so, this is a clear example of the path that SARS-CoV-2 could be traveling: from the protagonist of a pandemic to a future supporting actor in flu seasons. Only time will tell ”, says Paniz Mondolfi.

The director of the National Epidemiology Center, Marina Pollán, raises questions about future normality: “Will the masks be common? How will the deployment of telemeetings influence our psychology and our social interaction? Will the idea of ​​the other as a possible transmitter of infection change the way we relate to each other? ” The epidemiologist hopes that society will be able to learn some lessons from this pandemic, such as the need to improve care for the elderly and to strengthen the health system and scientific research. “We are intelligent beings, an experience like this should help us to recognize weak points in our way of organizing and improving them,” says Pollán. Elisabet Pujadas adds another unknown: the care that patients with chronic sequelae of the covid will need.

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