The package, delivered in January, forced the evacuation of all buildings within a 100-metre radius while explosive ordnance disposal experts were also called to the scene.
Production of the vaccine was halted, though the batch was able to be salvaged later.
X-ray images revealed the parcel contained equipment that could be used to make a viable explosive, including electrical wiring. A robot was subsequently used to move the item to a safe location before a controlled explosion was carried out as a precaution. Following the controlled detonation, it was confirmed the package did not contain a viable explosive.
Various pieces of paper were removed from the parcel, including several pages from a science manual and a calculator. There was also a letter addressed to Collins and a receipt for a supermarket transaction.
Kent police used supermarket CCTV to confirm that Collins was the owner of the receipt. A search of the address where Collins was detained also revealed a science book, with several pages missing. The missing pages were the same ones which had been placed in the parcel.
In custody, Collins admitted sending the package, Kent Police said. It added that Collins also provided extra detail that would only be known by the culprit.
He told detectives that he thought the items in the package would be useful to the people at the factory, but conceded that his actions may have caused harm.
His trial heard similar packages were also sent by Collins to 10 Downing Street, AstraZeneca, a US Air Force base in Gloucestershire, a laboratory in Wuhan and what appeared to be the leader of North Korea, Kim Jong-un, were intercepted.
Collins had developed an “obsessive interest” in the virus and vaccines, his trial was told.
Defence barrister Janice Brennan said Collins has a diagnosed personality disorder and has had an “obsession” with sending letters and packages for around 30 years.
She added: “He is a lonely and bored individual who does find it very difficult to deal with normal life.”
Passing sentence, Judge David Griffith-Jones QC told Collins: “A compulsion to send bizarre communications to different bodies or authorities is one thing and may be considered a harmless idiosyncrasy.
“It doesn’t explain your behaviour here, which was deliberately to send a bomb hoax knowing perfectly well that it would cause fear and mayhem.”
He said Collins’ insistence that the contents of the package were intended to help scientists at the Wockhardt site was “childish and quite perverse”.
Collins denied posting the package with the intention of causing a bomb scare but was found guilty at Maidstone Crown Court. He was handed a 27-month jail sentence on Wednesday, with the significant time he has already spent on remand to be deducted.
Detective inspector Adam Marshall, Kent Police’s senior investigating officer for the case, said: “Collins was fully aware of the impact his actions would have and chose to impede the vaccine rollout when the programme was still in its infancy.
“Although the device he sent was not a viable explosive, the people at the site had every reason to believe there was a threat to their safety and they acted in a diligent and thoroughly appropriate way.
“Thankfully the disruption Collins caused was not substantial, but his actions were an unnecessary distraction. I am pleased that we have been clearly able to prove his guilt and that he has been held to account.”