Many doctors feel that one of the ongoing problems which makes these individuals even more vulnerable is the sluggish uptake of booster vaccines, even in high-risk groups. While in the UK all over 50s and anyone younger with underlying health conditions qualify for a booster jab on the NHS this autumn – a total of 26 million eligible individuals – the latest statistics show that only half of those people have received their vaccines so far. Booster hesitancy is even more concerning in the US, with only 29.6% of Americans over 65 receiving their latest dose.