The reason why politicians and experts are so hesitant to make long term commitments on coronavirus restrictions is the risk posed by new variants.
As we saw in the winter with the Kent variant, new strains of the virus have the ability to send the pandemic into overdrive. In the winter it was because the new strain was more transmissible but there are fears that new strains may be more resilient to the vaccines leading to the possibility of more deaths and further lockdowns.
But what are the threats posed by the new variants?
The first thing to say is that viruses are constantly mutating and changing.
We see it with influenza every year where new strains will mean that the vaccines need to be tweaked.
However the good news is that experts are very good at mapping the new variants and tweaking the vaccines to counter them.
These are the key strains circulating right now:
This is the strain which contributed to the explosion in cases around Christmas in the UK.
According to Professor Francois Balloux who is the director of the Genetics Institute at University College London, the Kent strain "is clearly more transmissible and has expanded globally". He added: "It has also been associated to higher rates of hospitalisation and mortality."
Much of the issues countries in mainland Europe are facing are in part down to the spread of this strain.
Part of the reason why it is so much more easily spread is mutation called the N501Y mutation which affects the spike proteins of the virus which makes it easier for the virus to clasp on to human cells.
However there is some good news in that the Pfizer and AstraZenica jabs seem to be effective against it.
This study by Pfizer showed that there was a good immune response from people exposed to the N501Y mutation and this study showed that the AstraZenica vaccine was still 75% effective against it.
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South Africa variant (B.1.351)
The South Africa strain the same N50Y mutation as the Kent strain.
However it also has another mutation known as E484K which changes the part of the spike protean that our immune systems use to identify the virus and trigger a response.
The strain is not any more deadly than other strains though it is more easily transmitted.
There were some fears that the vaccines would not be as effective against the South Africa strain.
It is hard to be fully sure at this point. Some studies have suggested that Pfizer is not as effective though this doesn't mean that it won't give protection.
It is a similar situation with the AstraZenica jab with some studies suggesting that the vaccine is not very effective at stopping you catching the virus but it is likely to still prevent serious illness.
Further research is needed.
Brazilian variant (P.1.)
Like the stains above, the Brazil variant is not thought to be more deadly but it is spread more easily.
Professor Balloux said: "P.1 and B.1.351 have reached high frequencies locally and might be associated to a slightly higher risk of reinfection."
Regarding how effective the vaccines are it is a similar story to those above.
Regarding Pfizer this study found that there was still an immune response but it was not as effective w hereas this lab study suggested that the mutation made no differences to the vaccines effectiveness.
It is a similar situation with the AstraZenica jab.
Indian variant (B.1.617)
Cases in India are currently surging and the Prime Minister has just been forced to cancel a planned trip.
This strain has a double mutation that makes it better at evading the body's immune response including those produced by the vaccine.
Professor Balloux wrote on Twitter: "The B.1.167 'double mutant' circulating in India is an example of a variant of interaest lineage that is less concerning than a variant of concern but deserves close monitoring."
"Variant of Concern" and "Variant of Interest" are classifications given by the Centres for Disease Control and Prevention.
A Variant of Concern in more serious and can have the following attributes:
You can find more detail here.
Should you be worried?
Clearly all variants should be monitored but there are reasons for optimism.
Professor Balloux tweeted: "Despite multiple claims in the media, none of the variants in circulation targets a different host demography and/or is specifically more virulent in younger adults or children.
"None of the Variants of Concern in circulation bypasses immunisation provided by prior infection or vaccination."