This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at https://www.bbc.co.uk/news/health-55659820

The article has changed 72 times. There is an RSS feed of changes available.

Version 69 Version 70
What are the Covid variants and do vaccines still work? BA.4 and BA.5 Omicron: How worried should we be?
(3 months later)
The Omicron variant has become the dominant type of coronavirus circulating in many countries, overtaking previous variants, such as Delta. Two new fast-spreading subvariants of Omicron are causing fresh surges of Covid around the world.
It can be contagious, even if you have been vaccinated. But current vaccines are still providing good protection against severe illness. BA.4 and BA.5 were first identified in South Africa and may soon become the dominant strains in Europe and the US, health experts say.
What is Omicron? What exactly are BA.4 and BA.5?
A variant is a slightly altered - or mutated - version of a virus. There are thousands of Covid variants around the world, which is to be expected because viruses mutate all the time. Ever since it first emerged, Covid has been mutating or shape-shifting. The new genetic versions that keep appearing are called variants.
Omicron is strikingly different from some other Covid variants, and the one that started the pandemic, because of the long list of genetic mutations it has undergone. There have been a few major variants already, such as alpha and delta, that have caused massive waves of infection.
In particular, there are dozens of changes to the part of the virus targeted by the vaccine - the spike protein. The latest ones experts are concerned about - BA.4 and BA.5 - are very closely related to the Omicron variant behind last winter's wave.
This could make it better at sidestepping some of the protection offered by vaccines, or past infections with Covid. Omicron does appear to be highly spreadable, even in those who have been fully jabbed. They were added to the World Health Organization's monitoring list in March and have also been designated as variants of concern in Europe.
Two-thirds with Omicron say they have had Covid before Where are they spreading?
There are several types or sublineages of Omicron - including BA.1.1.529 and BA.2 - that have slightly different mutations from each other. They were spotted circulating in South Africa at the beginning of the year and now appear to be spreading much more quickly than other variants.
The World Health Organization says mounting evidence suggests BA.2 is proving to be a bit more transmissible than the others. Most European countries now have them and they look set to overtake other types of Covid soon. That's already happened in Portugal - BA.5 is now dominant there.
Is it worse than other variants? In the US, officials say they are seeing rising numbers of infections caused by the two new subvariants.
The evidence shows Omicron infections tend to be milder, since fewer people are getting sick enough with it to need hospital treatment compared to other variants. Covid infections in the UK are also showing early signs of a possible rise, driven by BA.4 and BA.5.
That is largely down to the amount of protection or immunity that people have built against Covid from past infections and vaccination, rather than changes to the virus itself. Australia has reported cases too.
Even so, if it is more infectious it could lead to more deaths in an unvaccinated population. Will they be harmful?
Are current vaccines good enough? Experts are unsure how hard countries will be hit.
Preliminary lab studies found two doses of Covid vaccine may not be enough, which is why some countries, including the UK, are giving people extra doses to boost their immunity. BA.4 and BA.5 Omicron are not thought to be any more lethal than other types of Covid.
UK research suggests boosters should provide good protection against severe illness. Lots of people have built up some immunity from past infections and vaccination, which is helping to make the disease less risky overall.
As with other Covid variants, the risk remains highest for people who are elderly or who have significant underlying health conditions. But the new subvariants do appear to be spreading more easily.
Although current vaccines may not be a perfect fit for Omicron, they are still the best line of defence against Covid. This is partly because immunity may be waning, but also because of the mutations the virus has undergone.
Many countries have also lifted their Covid restrictions, meaning people are mixing more, which gives the virus more chances to spread.
BA.4 and BA.5 appear to be able to infect people even if they've recently had other types of Omicron.
A wave of new infections could lead to more hospitalisations and some more deaths.
How can we protect against them?
As with other Covid variants, the risk or serious illness remains highest for people who are elderly, or who have significant underlying health conditions.
Although current vaccines are not a perfect fit, they are still the best line of defence.
They have cut the risk of severe illness against the other major Covid variants, including Delta, Alpha, Beta and Gamma.They have cut the risk of severe illness against the other major Covid variants, including Delta, Alpha, Beta and Gamma.
Doctors say it is vital people get the recommended number of doses to gain maximum protection against existing and emerging variants.Doctors say it is vital people get the recommended number of doses to gain maximum protection against existing and emerging variants.
Extra Covid booster in spring for over-75s and high riskExtra Covid booster in spring for over-75s and high risk
How many people have been vaccinated so far?How many people have been vaccinated so far?
How quickly could we get new vaccines against variants?How quickly could we get new vaccines against variants?
Updated versions of vaccines against Covid variants are already being designed and tested.Updated versions of vaccines against Covid variants are already being designed and tested.
Manufacturers could scale up production quickly too, and regulators have already discussed how to fast-track the approval process.Manufacturers could scale up production quickly too, and regulators have already discussed how to fast-track the approval process.
Moderna has already said it hopes to have an Omicron booster ready by March, although lab tests in animals suggest they may offer little advantage over standard shots.
What about the other variants?
The most potentially dangerous ones are called variants of concern.
UK officials have been keeping an eye on a recent descendant of the Delta variant, called AY.4.2 or "Delta plus", as well as "Domicron" or "Deltacron" Covid infections that combine Delta and Omicron.
Why do variants occur?Why do variants occur?
Viruses make carbon copies of themselves to reproduce, but they aren't perfect at it. Errors creep in that change the genetic blueprint, resulting in a new version of the virus.Viruses make carbon copies of themselves to reproduce, but they aren't perfect at it. Errors creep in that change the genetic blueprint, resulting in a new version of the virus.
If this gives the virus a survival advantage, the new version will thrive.If this gives the virus a survival advantage, the new version will thrive.
The more chances coronavirus has to make copies of itself in us - the host - the more opportunities there are for mutations to occur.The more chances coronavirus has to make copies of itself in us - the host - the more opportunities there are for mutations to occur.
That's why keeping infections down is important. Vaccines help by cutting transmission as well as protecting against serious Covid illness.