Scientists at the World Health Organization are saying that the latest coronavirus is likely to become endemic, or permanently circulating in the population, and that a deadlier pandemic lurks on the horizon.

Although public health experts have previously talked about the prospect that the new coronavirus or SARS-CoV-2 would not disappear but rather remain as a reoccurring albeit reduced health threat, the year-end remarks on Monday by WHO officials amounted to what one scientist called a "wake-up call" to governments around the world.

“It appears the destiny of SARS-CoV-2 is to become endemic, as have four other human coronaviruses," said Dr. David Heymann, the chair of the WHO’s strategic and technical advisory group for infectious hazards.

The four other human coronaviruses that have become endemic are responsible for about a quarter of all colds. The most recent endemic coronaviruses, HKU1 and NL63, were discovered in the wake of the 2003-2004 SARS outbreak.

Heymann said that the virus will continue to mutate as it reproduces in human cells, "especially in [geographical] areas of more intense transmission."

The agency's bleak projection comes as several countries have already begun mass vaccinations, but as the disease continues to inflict an alarming toll in hospitalizations and deaths—and as new concerns about the virus emerge. The United Kingdom is currently grappling with a new coronavirus variant that some experts say is proving to be significantly more transmissible. Meanwhile, doctors around the world are finding that a small number of people infected with COVID-19 appear to develop debilitating and potentially dangerous psychotic reactions.

During the press briefing, Dr. Mark Ryan, the head of the WHO emergencies program, echoed his colleague's prediction.

“The likely scenario is the virus will become another endemic virus that will remain somewhat of a threat, but a very low-level threat in the context of an effective global vaccination program," he said.

To date, only one human infectious disease, smallpox, has been declared eradicated by the WHO.

Perhaps in the most dire warning, Ryan said that the current pandemic was “not necessarily the big one." He said that despite having killed around 1.8 million people worldwide, the fatality rate for COVID-19 is "reasonably low" compared to other emerging diseases.

Although measuring how deadly a disease is in the midst of a pandemic is a difficult estimate, the WHO recently put the infection fatality rate of COVID-19 at 0.6%, or less than 1%. By comparison, the case fatality rate for SARS was nearly 10%. For Ebola, the number lies between 25% to 90%.

"This is a wake-up call," Ryan said.

Dr. Amesh Adalja, an infectious disease and pandemic preparedness specialist at the Johns Hopkins Center for Health Security, said the WHO's statements were not especially surprising. He predicted early on that the virus was headed towards becoming endemic.

"To me it wasn’t even a question," he said.

Adalja now projects that SARS-CoV-2 will become yet another virus people contend with year in and year out. While that may sound alarming, he said he believed the presence of an effective vaccine will relegate the disease from a public health emergency to another respiratory illness like influenza.

Meanwhile, Dr. Jeffrey Shaman, a Columbia University professor of environmental health sciences who recently wrote a paper about the scenarios in which the virus does become endemic, said he remained ambivalent about the outcome.

He said that while he has been reasssured by studies showing that people exhibit a strong and durable immune response to COVID-19, which would suggest that the virus could wane and disappear, he is also worried about the increasing evidence of repeat infections.

One study in Mexico, the largest to date on reinfections, found that at least 285 individuals contracted the disease twice. But it is still unclear how widespread the phenomenon is.

Similar to other Adalja, Shaman said that if the coronavirus does become endemic, repeat infections may be less severe or even benign with the help of vaccinations.

"It may not necessarily be something that’s overly taxing on society," he said.

One of the major lessons of the pandemic has been the importance of investing in public health infrastructure. Mayor Bill de Blasio recently announced plans for building a $20 million pandemic response institute in New York City to prepare for future outbreaks. The seed was planted more than 10 years ago, when, under Mayor Michael Bloomberg, city officials envisioned a thriving biotech sector in Manhattan that could draw on expertise from the city's top research facilities. The development that resulted on the East Side is now home to the city's Pandemic Response Laboratory, which processes coronavirus tests for 20,000 people a day.

But Shaman warned that complacency is always a risk, especially should several years pass without another major health emergency and as government officials deal with budget crises and competing priorities like the climate crisis.

"Unfortunately, the reality, especially for places with limited revenue streams, is that if this is in the rearview mirror and we are 5, 10 years beyond it, there are going to be different conversations about how you prioritize resources," Shaman said.