As the number of deaths and new cases of COVID-19 continue to fall in the UK, hopes of swift return to normality have been tempered by news that another variant of the virus has been added to the country's watchlist.

Public Health England confirmed 16 cases of a new variant that was first identified on February 15. The country's executive agency is now investigating the variant and has confirmed all individuals who tested positive and their contacts have been told to isolate.

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The latest discovery is a similar mutation to those identified in South Africa and Brazil, a variant that may help the virus evade the immunity offered by vaccination or prior infection say experts.

The cases were first identified by the UK surveillance system, which deploys some of the most advanced genomic testing techniques in the world.

It is thought this variant, which is currently considered a Variant under Investigation (VUI), probably originated in the UK. There are eight variants on the UK watch list: four are under investigation and four have been listed as a concern.

Officials are still trying to trace an individual known to have been infected with the mutation discovered in Brazil whose details on the test were incomplete.

That search is now focused on a group of nearly 400 households in the South of England as Public Health England revealed 85 cases have been confirmed in individuals who have not traveled abroad recently.

Friday also marks the sad anniversary of the first official fatality from COVID-19 in the UK – believed to have been a woman in her 70s who died in a hospital in southern England on March 5, 2020.

There have since been reports of other patients who have died earlier, perhaps as far back as January 2020, when COVID-19 was suspected but not officially registered either with Public Health England or the World Health Organization.

Scientists say variants continuing to appear may be of concern but is not unexpected. The sophistication of the UK genomic testing system could go some way to explaining why more variants are being identified in Britain.

All viruses mutate as they make new copies of themselves to spread and thrive and medical authorities do accept this may affect how well the current batch of vaccines will continue to work.

New vaccines, particularly "tweaks" of existing products, are already in the development pipeline, but their necessity raises the prospect of long-term repeat-vaccination programs being needed for some time to come.