The coronavirus that causes Covid-19 could become endemic like HIV, the World Health Organisation has said.
The WHO also warned against any attempt to predict how long it would keep circulating and called for a “massive effort” to counter it.
“It is important to put this on the table: this virus may become just another endemic virus in our communities, and this virus may never go away,” Mike Ryan, emergencies expert of the organisation, told an online briefing.
“I think it is important we are realistic and I don’t think anyone can predict when this disease will disappear,” he said on Wednesday.
“I think there are no promises in this and there are no dates. This disease may settle into a long problem, or it may not be.”
However, he said the world had some control over how it coped with the disease, although this would take a “massive effort” even if a vaccine was found – a prospect he described as a “massive moonshot”.
More than 100 potential vaccines are being developed, including several in clinical trials, but experts have underscored the difficulties of finding vaccines that are effective against coronaviruses.
Mr Ryan said the vaccines exist for other illnesses, such as measles, that have not been eliminated.
The pandemic also makes it "unlikely" that world leaders and thousands of other participants will be able to gather in New York in September for the annual UN General Assembly, Secretary General Antonio Guterres said in an interview with the French weekly magazine Paris-Match on Thursday.
The UN chief said he was looking at "various alternatives" made possible by digital technology, which he will present to member states.
Several UN envoys have already predicted that the meeting may be held by videoconference, especially as this year marks the 75th anniversary of the world body.
In a video messages, Mr Guterres on Wednesday urged governments, civil society and health authorities to address mental health needs arising from the pandemic, the lockdowns in place to help slow the spread and the deaths of loved ones, warning that psychological suffering is increasing.
Governments around the world are struggling to reopen their economies while still containing the virus, which has infected almost 4.3 million people, according to a Reuters tally, and led to more than 291,000 deaths.
Public health experts say extreme caution is needed to avoid new outbreaks.