Science correspondent Thomas Moore earlier answered all your questions on anything relating to COVID-19. Read what he had to say in the Q&A below.
Wednesday 5 January 2022 20:18, UK
Thanks for submitting all your burning coronavirus questions to our science correspondent Thomas Moore.
If you're joining us late, you can read his answers below.
The government's scientific advisers got their fingers burned by talking about herd immunity in the first wave of the pandemic, so it's unlikely that is now the strategy with Omicron.
It's more likely the government is resistant to taking action that may damage the economy without good evidence that the variant is a critical threat. At the moment the evidence isn't clear.
Herd immunity through infection is highly unlikely with COVID. Omicron's mutations allow it to evade some antibodies and the re-infection rate is higher than it was with Delta.
Immunity also wanes. And in the longer term there is turnover of the population 鈥� with just under 700,000 non-immune babies born each year.
How does not having a PCR after a positive lateral flow make sense? What about all the false positives people have regularly and the only thing keeping them at their work is a negative PCR?
Scientists at University College London estimate that if lateral flow tests are done correctly they are 80% accurate at detecting the virus. That's lower than PCRs, but they have the advantage of being a rapid home test.
The test is more likely to come back positive if people have a high viral load 鈥� in other words are more infectious. But a negative result is no guarantee that you don't have the virus and you should still be cautious around other people.
But there is a problem with false positives, as you say. It's about one in 1,000, so lots of people could be affected given the large number of tests being done.
But really importantly, Omicron is causing huge numbers of infections so if you test positive now it is much more likely to be a real result than a false positive.
You can always do another LFT 鈥� the odds of having two false positives are very small.
What percentage of current infections are Delta?
Will the Omicron variant become so dominant that it will completely wipe out the Delta variant?
The latest official data from labs using PCR tests that can distinguish Omicron and the Delta variants shows that 95.6% of COVID cases are likely to be due to the newer variant.
Omicron rapidly took over as the dominant strain, rising from barely 5% of cases to 90% in just three weeks. But the rise has dramatically slowed. In London the proportion is 96% and only edging up.
So Delta is still causing 7-8,000 reported cases a day and it's likely it will hang on in there for a while yet.
The vaccine is highly effective at stopping infection and transmission of Delta, but the variant can still spread in the five million or so unvaccinated people.
It's competing against the more infectious Omicron variant though and as more unvaccinated people become immune through infection, Delta will run out of road.
After 10 days of isolation I am still showing positive lateral flow tests and feeling unwell. Am I able to still pass the virus on? Should I be waiting to get two negative results in a row before I meet family and friends and return to work?
The NHS advice is that if you still have a temperature or feel unwell after 10 days you should continue to self-isolate and seek medical advice. A cough and changes to your taste and smell can last for several weeks and they aren't a reason to continue isolation.
The UK Health Security Agency says you don't need to continue with lateral flow tests after day 10.
The government recently shortened the self-isolation time to seven days, but only if lateral flow tests on day 6 and 7 are both negative and the tests were done at least 24 hours apart and you don't have a temperature.
If you end your isolation before 10 days you should limit contact with people outside our household, work from home if you can, wear a mask in crowds or poorly ventilated areas.
I'm 69, double jabbed and I got the booster on November 2021 - will I need a fourth dose and if so, when?
The efficacy of the booster jab is said to reduce after 10 weeks. This means that most people over 70 and "at risk" now have reduced protection but there have been no announcements about a further boost. Are we going to see growing numbers in those categories being hospitalised?
The UK Health Security Agency reported just before Christmas the first evidence of waning immunity from the booster. Ten weeks after the jab it estimates protection against symptomatic disease has dropped by 15-25%.
But it believes protection against serious disease that would need hospital admission will hold up for longer. The Joint Committee for Vaccination and Immunisation is monitoring hospital admissions for any sign that a new round of booster shots is needed.
Israel has begun giving a fourth dose to the over-60s and new evidence suggests it increases antibody levels by five times. There isn't yet evidence that it results in fewer hospital admissions, though.
The benefits of any medicine need to clearly outweigh any risks. Even though those risks are low with the vaccine it would be part of the decision making, as would the cost and logistics for the health service.
I am an 80-year-old season ticket holder at West Ham who had a booster at the beginning of October. Should I go to games?
This doesn't constitute medical advice Jeff, but these are the things you need to weigh up.
First the booster is 88% effective at preventing people ending up in hospital with Omicron. Or flip it round: if they get infected they run slightly more than a one in 10 risk of going to hospital.
There is no evidence yet that the protection from the booster against serious disease is waning, so that shouldn't be a problem.
Even if you are admitted to hospital you are likely to be less sick than if you had been infected with Delta back in the summer when you had only two doses of the vaccine.
Consider also the environment of the stadium. You'll be watching the games outside, which reduces the risk, though there is obviously a crowd and you'll have to go through more confined spaces to get to your seat. You can reduce your risk by wearing an FFP2 or FFP3 mask, which filters out almost all viruses in the air you breathe.
Against those risks you have to consider the benefits. There is a huge psychological boost to being at a game 鈥� particularly, in your case, with the Hammers having a great season.
With more and more cases, will there be more chances of mutations?
I hear talk of a new variant in France, could you elaborate on this news?
French researchers have detected a new variant with 46 mutations in 12 people living in the southeast of the country. They called it IHU and they believe the first case was a man who returned from Cameroon.
But just because the variant has lots of mutations, doesn't mean that it will spread rapidly, particularly with Omicron racing through the population, building up the nation's immunity as it goes.
New variants are more likely to evolve when there are lots of COVID cases. In reasonably healthy people who have been vaccinated, the virus causes a relatively short-lived infection.
But in people with immune systems that aren't working quite as well, the infection can linger for many weeks, giving the virus more time to evolve and then escape.
So, making sure effective vaccines reach every country as fast as possible will reduce cases 鈥� and the chances of new variants cropping up.
Where has the flu gone this year?
You're right, flu rates are really low at the moment. GP consultations for flu-like illness are slightly higher than last year 鈥� but only a fraction of what they were in the years before the COVID pandemic.
That's almost certainly because the same behavioural measures we use to reduce our risk of COVID 鈥� masks, hand hygiene, social distancing, etc 鈥� also slow the spread of flu.
Medical authorities had urged us all to have the flu jab this winter because the threat of Delta had been receding and more normal behaviour was returning.
But then came Omicron.
The flu season lasts well into the spring though, so the virus may yet surprise us!
If PCR tests are no longer required if a positive lateral flow test is returned, how are scientists going to track and monitor for new variants going forward? Surely this is not a great idea right now?
By scrapping PCR tests and relying on LTFs instead, how is the government's recording of data going to be accurate when it is guaranteed that many people will test positive but won't be bothered to record their result?
There are two really important downsides to not having a PCR test.
One is about tracking variants, as you say, SaraM. Some types of PCR test are able to detect the presence or absence of the virus's "S-gene". Delta comes back positive; Omicron is negative.
That was the first alert in South Africa that a new variant was beginning to spread 鈥� a scientist was puzzled why so many PCRs were coming back S-gene negative when Delta was, at the time, the dominant strain.
Without PCR tests the spread of a new variant is less likely to be picked up at an early stage 鈥� although if the next variant was also S-gene negative, the PCR test wouldn't flag it against the background of Omicron cases.
The second downside is rightly raised by Debbie CP. Scientists will lose sight of the size of the Omicron wave without widespread PCR testing. Not everybody reports their lateral flow result so the official stats are likely in future to be an underestimate of the real number of COVID cases.
But you have to balance those problems with the PCR testing system which is currently overwhelmed. More than 30% of tests are coming back positive 鈥� far higher than the 5% recommended by the World Health Organisation 鈥� which suggests there are many other cases going undetected because not enough testing is being done.
The need for a PCR test is only being dropped for those without symptoms. Anyone with a new cough, a high temperature or a loss of taste or smell still needs to self-isolate and take a PCR.
You can read more about the current rules surrounding PCR tests in the link below.
Sarah: