A coronavirus "super variant" worse than Covid-19 could emerge next year and every unvaccinated person is a potential super-spreader, according to an expert.
Immunologist Professor Doctor Sai Reddy, of the federal technology institute ETH Zurich, said a combination of existing strains could result in a new and more dangerous phase of the pandemic.
He warned: "Covid-22 could be even worse than what we are experiencing now."
As a result, multiple vaccinations will need to be prepared over the next few years as the world continues to fight the evolving threat, "maybe for the rest of our lives".
Speaking to Swiss German-language newspaper Blick, the scientist said due to the likes of Delta "this is no longer Covid-19" and warned anyone refusing to get jabbed will be infected at some point.
"The viral load of Delta is so great that anyone who has not been vaccinated and who is infected with the variant can be a super spreader," he continued.
Prof Dr Reddy said all children should get vaccinated because there is enough evidence to show the jabs are not a threat to under 12s.
And any that aren't are only helping to spread the virus quicker.
He went on to say "vaccination breakthroughs" will arrive in the autumn when cases will again increase, and could see the return of tough restrictive measures in some countries.
Prof Dr Reddy added: "It is very likely that a new variant will emerge where we can no longer rely solely on vaccination.
"That is why we have to prepare for several vaccinations over the next few years, which are constantly being adapted to new variants."
He said the Beta and Gamma variants can partially avoid antibodies and while Delta is "much more contagious" it hasn't "developed any escape mutations".
But some level of fresh combination is "inevitable", with Beta or Gamma becoming more infectious or Delta developing further.
The professor described the virus and the human immune system as "like two dancers".
"The immune system moves and the virus reacts. We will dance with the virus for a long time. Probably for years, maybe for the rest of our lives."