The outbreak of Ebola virus disease ( Evd ) in 2014-2015 was the largest known, with around 28,000 cases and 11,000 deaths, mainly affecting West Africa ( Guinea, Liberia and Sierra Leone ). Evd was declared over in June last year.


The Scottish nurse, Pauline Cafferkey, infected while working in Sierra Leone in 2014, has been cleared of misconduct charges by the Nursing and Midwifery Council. On her fourth admission to hospital ( Queen Elizabeth University Hospital, Glasgow ) since returning from West Africa, she tested negative for the virus ( October 2016 ).


There’s still a chance, hopefully small, that cases of Evd may occur in Africa.


We’ve known about Evd for over 40 years, but it took the last outbreak to stimulate overdue investments in vaccines and drug treatments.


Several " candidate " vaccines have been developed and tested in clinical trials. As there is no identifiable high-risk population that can be targeted without the presence of an Evd epidemic, and Evd outbreaks are unpredictable, it’s just as well that vaccine trials are now already established.


Treatments need to be based on good evidence, not anecdotes.


Clinical trials must be regulated and judged ethical. They are usually staged in four " phases " - involving progressively larger groups of people.


Trials of Ebv vaccines may involve " ring vaccination " of " clusters " of individuals at high risk of infection, due to social /geographical connection to a known case. Ring vaccination helped smallpox eradication in the 1970s.


Towards the end of last year final trial results showed a highly effective vaccine for preventing Evd, now being " fast tracked " for regulatory approval. This was an " open-label " trial ( both researchers and participants knew whether vaccination was immediate OR delayed by 21 days ). It wasn’t possible for the more common " blind " trial, where those taking part don’t know the treatment being given. The vaccine was also " recombinant " ( from more than one source, possible because DNA molecules from all organisms share similar chemical structure ), and " vector-based " ( " carried " by a harmless virus, to make more effective ).


The vaccine WAS effective in preventing Evd in all of almost 6,000 people receiving it.


It could be available by next year ( far less time than most new vaccines take ), and the manufacturer ( Merck ) has made 300,000 doses available, thanks to $5m from " GAVI " ( Global Vaccine Alliance).


Good news indeed, although more lives could be saved if countries invested in vaccines and treatments BEFORE outbreaks, rather than during them - unfortunately NOT always possible to predict, whether ‘flu, Zika, or other infection.