Three years ago, Covid-19 rocked the planet. The pandemic is not over yet, and researchers warn that other epidemics are expected, drawing lessons from the crisis that spawned it to better prepare for it. The World Health Organization (WHO) warned in early December that “we are not yet” at the end of the pandemic.
While at least 90% of the world’s population has some form of immunity, “gaps in surveillance, testing, sequencing and vaccination continue to create the perfect conditions for the emergence of a new worrisome variant that could cause significant mortality,” warned Director-General Tedros Adhanom Ghebreyesus.
From pandemic to endemic virus
The World Health Organization is the one declaring the end of the pandemic. “It is always a very important moment, often controversial,” Philippe Sansonetti, a microbiologist, noted during a symposium on Wednesday at the Pasteur Institute, considering that the organization may not have been ready to “declare the end” of the pandemic.
What experts expect is a gradual transformation of the pandemic into an endemic virus, one that continues to spread and causes regular resurgences. This is the case today with measles or seasonal flu.
Covid and its “bad cases”
The SARS (Severe Acute Respiratory Syndrome) epidemic, which spread across the world in 2003 and claimed nearly 800 lives, was eradicated through isolation and quarantine measures. A virus, smallpox, had already been declared “eradicated” in 1980 thanks to a vaccination campaign organized by the World Health Organization. But this scenario is still extremely rare.
“To eradicate the virus, it is essential that the disease is clinically visible, that there is no animal reservoir, and that there is a highly effective vaccine that protects life. Covid-19 ticks all the wrong boxes,” said Philippe Sansonetti. Some Covid vectors -19 is already asymptomatic, which affects isolation measures.Unlike smallpox, the virus is transmitted to animals and can continue to circulate between them and infect humans again.Finally, vaccines provide good protection against severe forms of the disease but little against reinfection, Booster doses are still necessary.
Humans encourage the transmission of viruses
For Etienne Simon Laurier, director of the Evolutionary Genomics Unit for RNA Viruses at the Pasteur Institute, “today we allow the virus to circulate too much”: every time it infects a person, mutations can appear. It is likely to cause it. to evolve into more or less severe forms. He warned, “Even if it were appropriate for all of us to believe it, we have no reason to believe it would become more sympathetic.”
In addition, other respiratory viruses can appear: since the emergence of Sras, Mers and Sars-Cov2, “dozens of coronaviruses have been found in bats that are likely to infect [l’humain] Arnaud Fontanet, a specialist in emerging diseases at the Pasteur Institute, noted. About 60%/70% of emerging diseases are of zoonotic origin, that is, they are transmitted naturally from vertebrate animals to humans and vice versa. By occupying more and more swathes of the world, by traveling, by intensifying their interactions with animals, humans are contributing to ecosystem disruption and favoring the transmission of viruses.
Expect rather than respond
For Arnaud Fontanet, “a lot can and should be done at the beginning of the epidemic” to prepare for it. Thus, in 2020, Denmark decided to confinement very early, which allowed them to get out of it more quickly, he said. Another essential: “having the ability to develop tests very early,” at the start of an epidemic, so as to isolate patients very quickly. “Unfortunately, today we are still in reaction, not in anticipation,” the researcher laments.
At the international level, the concept of “One Health”, which emerged in the early 2000s, promoting a global approach to health issues with close links between human health, animal health and the environment, is a new concept. A draft global agreement on managing epidemics was also under discussion last week in Geneva, hoping to avoid the mistakes that have characterized the fight against Covid-19.
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