Experts have warned that the Omicron variant of coronavirus "poses a greater risk" to people with blood cancer.
Meanwhile, experts from the Francis Crick Institute and The Royal Marsden NHS Foundation Trust are examining the effects of a fourth booster dose in blood cancer patients.
They are currently examining antibody levels in blood cancer patients which help to protect the body by identifying and attacking viruses - the team is focusing on Omicron-protecting antibodies, reports Wales Online.
Read more:
While patients with solid tumours generate normal amounts of antibodies, those with blood cancer who have received three doses of the Covid-19 vaccine produce them less frequently.
According to the study, only 56 per cent of those with blood cancer generated neutralising antibodies.
This means after receiving three doses of the vaccine, 44 per cent of patients with blood cancer did not generate antibodies that could protect against Omicron.
The researchers note that antibodies are not the only line of defence with other parts of the immune system offering protection.
But they have added that the study supports the need for a fourth jab for immunocompromised groups of people.
“We found that a third vaccine dose boosted the neutralising response against omicron in patients with cancer, but the effect was blunted in patients with blood cancer compared to those with solid cancer,” they wrote.
It supports UK policy which offers a fourth jab of the vaccine to some patients.
In the UK, people with severe immunosuppression aged 12 and over are offered three Covid-19 jabs as an initial course of vaccination - they are then offered a fourth boster.
Dr Samra Turajlic, lead author and group leader at the Crick and consultant medical oncologist at The Royal Marsden, said: “The pandemic has been especially difficult for people living with cancer and up-to-date information about immunity levels are particularly important for this vulnerable group.
"We now know that the immune response to vaccines in patients with solid cancers are robust after three doses as compared to people without cancer, even against the new Omicron variant.
“But for people with blood cancers, Omicron poses a greater risk. These patients should remain cautious and come forward for their fourth booster dose as soon as it’s available to them.
“Protecting this vulnerable group is important, especially in the light of the recent easing of Covid-19 restrictions in the UK such as ending mandates requiring people to wear a face mask.
"Public health measures must be inclusive and supportive of everyone, including vulnerable people and their carers.”
