The outbreak was linked to a single nightclub in Canterbury over one weekend and saw 21 people diagnosed with invasive meningococcal disease in one week. All those affected required hospital treatment, nine needed intensive care and two people tragically died.

The analysis revealed the outbreak bacteria had acquired new traits from harmless bacteria circulating nearby making them more likely to cause disease.

It also revealed that same changes that made it so dangerous may also explain why it did not continue to spread widely.

The public health organisation said that thanks to every culture-confirmed case of meningitis in England being routinely whole-genome sequenced as part of its national surveillance programme since 2010, scientists were able to identify the outbreak strain, trace its genetic background and assess important characteristics at speed.

The UKHSA said this information supported the rapid public health response, including contact tracing, antibiotic prophylaxis and targeted vaccination, which was operating within days of the first case being confirmed, helping to bring the outbreak under control and prevent further spread.