Nearly two-thirds of the UK's adults have received the first dose of a COVID-19 vaccine, making the nation one of just a few globally on its way to so-called population immunity.
The UK has in turn taken steps to reopen the economy after a lockdown to tackle a deadly COVID-19 spike earlier this year.
By June 21, the government hopes to lift nearly all social contact restrictions in the country.
But multiple experts have warned that lifting restrictions too quickly could fuel another rise in infections and possibly a "third wave".
"We can't be complacent...we've seen how this story goes," Prime Minister Boris Johnson warned in early April when he began easing the lockdown, adding that authorities were unsure how good the "vaccine shield" could protect against rising infections.
Earlier this week Johnson said there "probably will be another wave of the disease" but that the government had built up "robust fortifications against the next wave".
Surge in cases expected despite vaccination
UK epidemiological models have shown that easing all restrictions by June could lead, in the worst case scenarios, to infection levels and deaths seen in the first wave of the pandemic when 40,000 people died in the UK.
Other UK models analysing lockdown easing and vaccination rates gave smaller estimates, including one from Imperial College that estimated in its "central" analysis that there could be 15,700 additional deaths in England by June 2022 if restrictions are eased.
"I think it is likely that we will have a surge," Linda Bauld, a professor of public health at the University of Edinburgh, told Euronews.
Government models "are all predicting that we will have a future surge of this virus despite vaccination, not in the next few months, but probably heading into the autumn and winter," she added.
Bauld said this is largely because not everyone will be fully vaccinated by the autumn, the vaccines are not 100% effective and the duration of their protection is unknown.
"The modelling consensus is clear that we will have what is called a third wave," said Jonathan Van-Tam, England's deputy chief medical officer, at Wednesday's Downing Street briefing.
"I am personally hopeful that if the vaccine programme continues at pace and continues to be as successful as it's been the 'third wave' so to speak might just be a third upsurge and much less significant because of the delinking of cases to hospitalisations and deaths."
But he emphasised that it would be "inconceivable" to have "no further bumps in the road" between now and this time next year.
Can't go 'completely wild' yet
"If we all go completely wild ... and just ignore everything that we've learnt over this last year in terms of social restrictions, there will be another wave. And that wave will be much larger," Professor Anthony Harnden, deputy chair of the UK's Joint Committee on Vaccination and Immunisation, warned the House of Commons' science and technology committee on Wednesday.
"We need to celebrate our success with vaccines, they are tremendously effective, the data is hugely encouraging but we also need to be cautious because we don't want to see what's happening in other parts of Europe in other parts of the world happening in the UK," he added.
Dr Mary Ramsay, Public Health England's head of immunisation, also explained to the science committee that the main reason infections came down in the UK was due to distancing restrictions and not just vaccination.
For some, Israel's example has inspired hope that vaccination will have an impact as they have fully vaccinated half of their population. Infections and deaths there have plummeted despite reopening.
But Prof Bauld says the UK isn't quite there yet.
"The big difference between the UK and Israel is that Israel has given most people their second dose and at the moment we’ve only got 20% of the UK population who’ve had their second dose so that’s the whole population and of adults it’s one in four so we’re nowhere near as well protected," Bauld said.
Government estimations show that the percentage of the population who are fully vaccinated could influence any future "third wave" as well.
Delaying lockdown easing could prevent rising infections, experts argue
In a new report, some experts say that delaying the easing of restrictions could help to keep infections at bay in addition to prioritising mRNA vaccines and vaccinating adolescents.
"If the pace of vaccination cannot be increased towards the rates achieved in March, the government should consider delaying step 4 of the roadmap by a month until the summer holidays when transmission is anticipated to be lower," argue Ian Mulheirn and David Britto in a report from the Tony Blair Institute for Global Change.
They also say that teenagers should be vaccinated to increase the percentage of the population who will receive the vaccine.
Pfizer recently announced that their COVID vaccine was 100% effective in teenagers between 12 and 15 years old. But trials are ongoing in younger age groups with results expected by the end of the year.
Mulheirn and Britto suggest relying more on the mRNA vaccines from Pfizer and Moderna which have shown to prevent infection "marginally" more than the AstraZeneca vaccine, as well.
UK health minister Matt Hancock already announced that the UK secured an additional 60 million Pfizer-BioNTech doses to be used as booster jabs in the fall.
Mulheirn and Britto say that these three steps could prevent 77 per cent of the anticipated deaths between now and June 2022 as predicted by the UK models.
While they contend that there is "huge uncertainty" over whether there will be no further spread of the virus or a massive third wave in the UK, the authors argue the third wave does not need to be "inevitable" if government measures remain in place.
Bauld explains that government policymaking will have more of an impact than people's behaviour.
"If the government asks people to do things, like stay at home, wear face coverings, adhere to physical or social distancing, the vast majority of people have done it pretty consistently since they were asked and they probably will do it again in the future," Bauld said.