The government has given the green light to people across the UK gathering in groups of up to three households of any size from 23 to 27 December. How can those who decide to meet up with people this Christmas minimise the risks?

Reconsider the nature of Christmas

If you are not in a high-risk group it is not entirely crazy to meet a few people in the safest way possible, suggests Lucy Yardley, a professor of health psychology at the University of Bristol. “But what really isn’t going to work is the traditional Christmas done in the traditional way.”

So think flexibly. Consider mince pies and presents in the garden, chestnuts roasting on an outdoor fire, a bracing walk with a picnic, or even eschewing communal eating altogether – since a Christmas lunch inevitably means removing face coverings and often sitting in close proximity while chatting for prolonged periods, all activities best avoided.

Isolation before Christmas

If you are ill, you should obviously stay at home. But to reduce the risk of asymptomatic coronavirus transmission, you could consider self-quarantining in the run-up to Christmas. “If you are able to completely self-isolate for 14 days beforehand then you really are very safe,” says Yardley. “Five days isn’t enough, although it is better than nothing. Ten days would be better, and 14 days better still.”

Try to avoid seeing everyone at once

Just because three households are allowed to form a Christmas bubble that does not make such an event safe, particularly if your home is small. The more people you cram inside the higher the odds that one of you is unwittingly carrying the virus and the harder it is to maintain social distancing.

Covid-secure your home

There are many ways of reducing the risk of transmission indoors, including disinfecting frequently touched surfaces, wearing a mask, maintaining a 2-metre distance from others, and using separate bathrooms.

Ventilation is particularly important, and in well-insulated modern homes a single open window may not be enough.

“What really makes a difference is having some airflow through the house, so keep the doors open and a window at the top and the bottom of the house ajar,” says Gabriel Scally, visiting professor of public health at the University of Bristol, and a member of Independent Sage. The same applies to individual rooms: keep doors and windows open.

Remember home does not mean safety

Cancelling small gatherings is one of the most effective strategies for preventing the transmission of Covid-19, finds a recent study in Nature Human Behaviour.

Gathering in the “safety” of your own home is particularly risky, precisely because we perceive it to be safe, warns Stephen Reicher, a professor of social psychology at the University of St Andrews. “We feel relaxed at home, and that can be dangerous because it may mean we let down our guard.”

Learn how to politely say no

It can be difficult to push a loved one away if they approach you for a hug or invite you indoors. To avoid seeming rude you could think through potentially awkward situations and try to pre-empt them. “Try to frame your saying ‘no’ as an offer, rather than a rejection,” suggests Reicher. “So, don’t say, ‘don’t come near me’, but rather ‘shall I keep my distance so I don’t infect you?’ instead.”

Table manners

If you have the space and furniture available, consider a U-shaped table arrangement or even separate tables for different households.

“Having people from different households directly facing one another isn’t a good idea,” says Linda Bauld, a professor of public health at the University of Edinburgh. Neither is playing background music, which encourages people to raise their voices and emit more droplets from their mouths.

Avoid touching things that other people have touched, including shared food dishes. Ideally, guests should bring their own crockery and cutlery, and take it with them when they leave.

Think carefully about who does the washing up. “Certainly, it shouldn’t be the most vulnerable person,” says Yardley. “Also remember that when the guests leave, any virus will remain in the house, so it’s best not to have the most vulnerable person hosting an event.”

For additional tips on staying safe at home see the Germ Defence website, which Yardley and colleagues developed.

Timing matters

The amount of time you spend indoors makes a difference to the build-up of virus in the air. From a contact-tracing perspective 15 minutes of sitting within 2 metres of someone indoors is the definition of “close contact”. Shorter visits are therefore better than longer visits.

If you are planning to visit relatives or friends or invite in guests consider doing it in the morning rather than the afternoon or evening. It is easier to cajole people outdoors when there is daytime light, and you might be less likely to consume alcohol.

“If alcohol is involved people are likely to stay longer, and physical distancing often becomes more difficult,” Bauld says.

Outdoors is best but not risk-free

If you are considering a traditional Boxing Day walk, try to keep your distance from other households. Although the risks of transmission are lower outdoors, 2 metres is still the ideal minimum.

If you are taking part in carol singing (if it is permitted under still-to-be-published government guidance) you should probably stand even further away. “Singing to each other across the garden is fine though,” Yardley says.

Consider a midsummer Christmas

Postponing gatherings with family or friends until the summer could be the safest strategy of all.

“We could decide to love each other by keeping our distance, and then planning a bloody great party for Midsummer’s Day,” Reicher suggests. “Personally, I’ve always liked the notion of a Christmas barbie on the beach.”