A laboratory and clinical training centre that pivoted to run a Covid testing operation says it is now processing up to 5,000 tests a day - and that it "cannot recruit fast enough".
Liverpool-based BioGrad Diagnostics is one of the cheapest approved providers of PCR testing firms on the Government's official list.
The Liverpool Science Park-based firm has had a whirlwind year - creating jobs and opening new clinics across the country - and is now expanding its footprint in Merseyside.
People travelling to or arriving from abroad are required to take pre-departure and post-arrival Covid PCR tests, regardless of whether the destination is on the Government's green, amber or red list of countries.
At the time of writing, BioGrad's tests were the fourth cheapest on the approved list of over 350 providers.
The firm's CEO, Dr Natalie Kenny said: "We cannot take on enough people, because our website is selling out within an hour. Then we restock back up again and it sells out again - it's constant, so that is great."
Asked whether she expected the firm to achieve such success when launching Covid testing early on in the pandemic, Dr Kenny said: "It wasn't planned. It wasn't organised. We just wanted to help out and do the right thing. I think that came through.
"A lot of our clients are clients we've already dealt with previously, and then they would recommend us to other people who would recommend us to other people.
"We are a small company because we fly under the radar. We don't really shout too much - it's all word of mouth."
The firm in February announced it was creating 150 jobs in a major investment drive and push into London.
Now, it is expanding further, opening a site in Bootle to complement the existing Liverpool Science Park site.
The new premises, located at St Hugh's House on Stanley Road, will offer operations including a new clinic, clinic administration, a customer service call centre, marketing and HR departments across two floors totalling more than 7,500 sq ft.
Looking ahead, the firm is looking forward to focussing on its clinical and lab-based training for science students, researchers and teachers once more.
Dr Kenny added: "We want to maintain our our credibility and morality in amongst amongst all this. We're a very strong advocate for the Northern Powerhouse and Liverpool and business.
"We want to fly the flag for Liverpool internationally, which we have been doing through our training programme, but we want to be able to maintain that standard of service and the ethical code through testing too."
