A needle-stick injury - where a needle used to treat a patient accidentally pierces the skin of a health worker - is a potentially serious source of infection.
The English authorities say the health care workers have been admitted for assessment to the Royal Free Hospital in London. The hospital says they are "likely to have been exposed" to the virus but have not been diagnosed with Ebola and do not have symptoms.
According to Public Health England (PHE), the first individual arrived in England on January 31st and the second on February 2nd.
They will be monitored for a total of 21 days of incubation period, in line with PHE procedures for returning health care workers.
Both individuals were exposed to the virus in a frontline care setting in Sierra Leone, via needle-stick injuries that occurred while treating patients diagnosed with Ebola.
PHE say decisions on the immediate and ongoing care of the individuals will be made by the clinical team at the Royal Free Hospital and ask that their "confidentiality is respected at this time."
The two Ebola needle-stick incidents "appear to be unrelated"
Professor Paul Cosford, Director for Health Protection and Medical Director at PHE, says strict protocols were followed on bringing the individuals back to England, and:
"We would like to emphasize that there is no risk to the general public's health. Our thoughts are with both of the health care workers, and their families, affected at this time."
Mark Francois, Minister of State for the Armed Forces, says the two incidents - although similar and occurring within a short space of time - appear to be unrelated, and notes:
"Our personnel receive the highest standard of training and briefing prior to deployment, including on the use of the specialized personal protective equipment."
He says on a recent visit he witnessed "first-hand the bravery and commitment of the personnel who are doing such a fantastic job in Sierra Leone. Their efforts are deserving of the highest praise and we wish all the best for their 2 colleagues who are now in the UK."
Needle-stick injuries are a potentially serious source of infection
Needle-stick injuries are accidental wounds caused by needles puncturing the skin. They can occur at any time when health care workers are treating patients with hypodermic syringes or when they take the needles apart or dispose of them.
Injuries caused by "sharps" such as needles, blades and scalpels are a potentially serious source of infection because there is a high risk of a blood-borne virus entering directly into the bloodstream.
The Ebola epidemic in West Africa is the largest since the virus was first discovered in 1976. The countries worst affected are Guinea, Liberia and Sierra Leone.
There have been over 22,000 probable and suspected cases of Ebola virus disease and over 8,700 deaths since cases were first notified to WHO in March 2014. Among these, 816 health workers have become infected and 488 have died.
Meanwhile, Medical News Today recently learned that the latest WHO situation report says the number of new cases in a week in West Africa has fallen below 100, the focus of the response to Ebola is now shifting from slowing transmission to ending the epidemic.