Anyone planning trips to countries added to the list will be asked to self-isolate for two weeks on their return.
If that affects your ability to work, it could mean having to cancel your trip.
In cases where only quarantine rules are changed, you are unlikely to be able to get your money back from tour operators or hotels.
However, if the Foreign Office also advises against travel to a country, which it has in many cases, then a refund for the whole package holiday or the opportunity to rearrange should be granted.
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Media captionFlying is a very different experience in the age of coronavirus
I organised my own trip. How am I covered?
If you booked flights and accommodation separately and now think you cannot travel owing to quarantine, you may face a large bill for a holiday you will not take.
Flights, trains and ferries to France and the Netherlands are likely to continue to run. If your trip is not cancelled by the operator, you cannot claim a refund.
Consumer organisation Which? says this could leave people “significantly out of pocket”.
Instead, you may want to rebook for another time, although that can carry a hefty fee with some airlines. Tickets for trains through the tunnel and ferry tickets may be more flexible, depending on which ticket you bought.
Accommodation rebooking or refunds depend on the terms, and generosity, of the owner.
Will travel insurance cover me if I get coronavirus?
Where the Foreign Office advice states UK residents should not travel, it is very unlikely that any travel insurance will be valid.
In countries where travel is acceptable, according to the Foreign Office, cover will depend on your policy.
Most will cover treatment for illness and injury while overseas, but not all will do so for coronavirus-related illness.
Some policies are now being sold that will cover emergency treatment or repatriation to the UK for Covid-19 contracted while in a resort.
There will be relatively little protection for those who cannot travel because they develop symptoms just before they are due to go on holiday.
Travel companies are unlikely to give a refund, or allow people to rearrange.
What about insurance if I have to self-isolate?
The government says people must self-isolate for 14 days after coming into contact with someone with coronavirus.
This could lead to cancelled or delayed holidays.
Insurance broadly falls into three categories:
Anyone who had a travel insurance policy bought or renewed before early March may still be able to make a claim for such a cancellation
Renewals of annual policies may now be unavailable, or have coronavirus exclusions. In other words, the terms may have changed
People buying travel insurance now are unlikely to be covered for coronavirus-related delays or cancellations
Can I get a refund for cancelled flights or holidays?
Yes, but there have been delays for many people who have been seeking refunds for cancelled holidays.
The Association of British Travel Agents (Abta) told BBC News that people “absolutely have the right to a refund” for package holidays cancelled by a provider, but payments would take longer than the 14 statutory days.
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If your flight is cancelled, you are also entitled to a full refund to your original form of payment, within seven days. Huge backlogs mean these have been delayed considerably, prompting complaints to airlines and the regulator, the Civil Aviation Authority.
If you are offered a voucher, or a free rebooking instead of cash, you can accept or refuse it.
But if the airline later folds, the voucher will probably become invalid.
If you rebook and later decide against going on a flight that has not been cancelled, you will have lost your right to a refund and are unlikely to be covered by your travel insurance.
The Association of British Insurers said travel insurance was to cover losses incurred by unforeseen circumstances and coronavirus no longer met those criteria.
People should also pay attention to “disruption cover” in terms and conditions, which may, or may not, pay out for costs such as unused hotel bookings or car hire.
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A medical test that can show if a person has had the coronavirus and now has some immunity. The test detects antibodies in the blood, which are produced by the body to fight off the disease.
Asymptomatic
Someone who has a disease but does not have any of the symptoms it causes. Some studies suggest some people with coronavirus carry the disease but don’t show the common symptoms, such as a persistent cough or high temperature.
Containment phase
The first part of the UK’s strategy to deal with the coronavirus, which involved trying to identify infected people early and trace anyone who had been in close contact with them.
Coronavirus
One of a group of viruses that can cause severe or mild illness in humans and animals. The coronavirus currently sweeping the world causes the disease Covid-19. The common cold and influenza (flu) are other types of coronaviruses.
Covid-19
The disease caused by the coronavirus first detected in Wuhan, China, in late 2019. It primarily affects the lungs.
Delay phase
The second part of the UK’s strategy to deal with the coronavirus, in which measures such as social distancing are used to delay its spread.
Fixed penalty notice
A fine designed to deal with an offence on the spot, instead of in court. These are often for driving offences, but now also cover anti-social behaviour and breaches of the coronavirus lockdown.
Flatten the curve
Health experts use a line on a chart to show numbers of new coronavirus cases. If a lot of people get the virus in a short period of time, the line might rise sharply and look a bit like a mountain. However, taking measures to reduce infections can spread cases out over a longer period and means the “curve” is flatter. This makes it easier for health systems to cope.
Flu
Short for influenza, a virus that routinely causes disease in humans and animals, in seasonal epidemics.
Furlough
Supports firms hit by coronavirus by temporarily helping pay the wages of some staff. It allows employees to remain on the payroll, even though they aren’t working.
Herd immunity
How the spread of a disease slows after a sufficiently large proportion of a population has been exposed to it.
Immune
A person whose body can withstand or fend off a disease is said to be immune to it. Once a person has recovered from the disease caused by the coronavirus, Covid-19, for example, it is thought they cannot catch it again for a certain period of time.
Incubation period
The period of time between catching a disease and starting to display symptoms.
Intensive care
Hospital wards which treat patients who are very ill. They are run by specially-trained healthcare staff and contain specialist equipment.
Lockdown
Restrictions on movement or daily life, where public buildings are closed and people told to stay at home. Lockdowns have been imposed in several countries as part of drastic efforts to control the spread of the coronavirus.
Mitigation phase
The third part of the UK’s strategy to deal with the coronavirus, which will involve attempts to lessen the impact of a high number of cases on public services. This could mean the NHS halting all non-critical care and police responding to major crimes and emergencies only.
NHS 111
The NHS’s 24-hour phone and online service, which offers medical advice to anyone who needs it. People in England and Wales are advised to ring the service if they are worried about their symptoms. In Scotland, they should check NHS inform, then ring their GP in office hours or 111 out of hours. In Northern Ireland, they should call their GP.
Outbreak
Multiple cases of a disease occurring rapidly, in a cluster or different locations.
Pandemic
An epidemic of serious disease spreading rapidly in many countries simultaneously.
Phase 2
This is when the UK will start to lift some of its lockdown rules while still trying to reduce the spread of coronavirus.
PPE
PPE, or personal protective equipment, is clothing and kit such as masks, aprons, gloves and goggles used by medical staff, care workers and others to protect themselves against infection from coronavirus patients and other people who might be carrying the disease.
Quarantine
The isolation of people exposed to a contagious disease to prevent its spread.
R0
R0, pronounced “R-naught”, is the average number of people who will catch the disease from a single infected person. If the R0 of coronavirus in a particular population is 2, then on average each case will create two more new cases. The value therefore gives an indication of how much the infection could spread.
Recession
This happens when there is a significant drop in income, jobs and sales in a country for two consecutive three-month periods.
Sars
Severe acute respiratory syndrome, a type of coronavirus that emerged in Asia in 2003.
Self-isolation
Staying inside and avoiding all contact with other people, with the aim of preventing the spread of a disease.
Social distancing
Keeping away from other people, with the aim of slowing down transmission of a disease. The government advises not seeing friends or relatives other than those you live with, working from home where possible and avoiding public transport.
State of emergency
Measures taken by a government to restrict daily life while it deals with a crisis. This can involve closing schools and workplaces, restricting the movement of people and even deploying the armed forces to support the regular emergency services.
Statutory instrument
These can be used by government ministers to implement new laws or regulations, or change existing laws. They are an easier alternative to passing a full Act of Parliament.
Symptoms
Any sign of disease, triggered by the body’s immune system as it attempts to fight off the infection. The main symptoms of the coronavirus are a fever, dry cough and shortness of breath.
Vaccine
A treatment that causes the body to produce antibodies, which fight off a disease, and gives immunity against further infection.
Ventilator
A machine that takes over breathing for the body when disease has caused the lungs to fail.
Virus
A tiny agent that copies itself inside the living cells of any organism. Viruses can cause these cells to die and interrupt the body’s normal chemical processes, causing disease.
