A vaccine which could help prevent ear infections in young children has been developed by Czech scientists.
Ear infections are common in childhood
Also known as acute otitis media, the infections can be very painful and - very rarely - cause long term damage.
The vaccine was effective against two bacteria - the streptococcus pneumoniae and haemophilus influenzae, the Lancet reported.
But a UK ear expert said there concerns about vaccinating children against what was generally a mild infection.
The vaccine tested contained proteins derived from both streptococcus pneumoniae and haemophilus influenzae.
Almost 5,000 infants were either given this vaccine, or a hepatitis A vaccine, at various ages between three and 15 months.
When the researchers followed them up at the age of two, 333 of the children given the new vaccine had a middle ear infection, compared with 499 in the control group.
The vaccine was shown to be effective against both disease-causing bacteria.
Dr Roman Prymula, from the University of Defence at Hradec Kralove, who led the study, said: "We found a reduction in ear, nose and throat specialist-confirmed episodes of acute otitis media by about a third in infants in the vaccine group compared with controls."
The researchers say the findings are important because both bacterium are significant causes of lower respiratory tract infections.
But Antony Tucker, an ear, nose and throat surgeon at Bradford Royal Infirmary, told the BBC News website: "The suggestion here is giving a vaccination against something that isn't a life-threatening condition."
He said there were also questions about the cost of immunising all children against a short-term, usually mild infection.
Mr Tucker added: "In addition, only a proportion of ear infections are caused by bacteria, and only some of those by these bacteria."