Image copyright Getty Images Image caption In Cambodia, flu has already broken out
The US has been racing to vaccinate young children, just in time for winter flu season, but some European countries are holding back.
According to the US Centres for Disease Control and Prevention (CDC), 4.5 million youngsters are expected to get the vaccine this season.
But Europe says it is not “sufficiently developed”.
Cambodia has already seen a flu outbreak, while Romania has warned of a possible rise in cases.
The World Health Organization says there is “evidence of decreased vaccine availability in some countries in Europe, while others, including some in southern Europe, have weak demand”.
In the UK, the vaccination is free for all under-fives and there are up to 36 doses available each year.
Scientists and health officials recommend everyone between five and 64 years old be vaccinated, and the same age range gets a shot alongside the child.
There is no one-size-fits-all vaccine and in some situations parents may want to wait until their child has reached the maximum suggested age.
It takes about two weeks for the body to develop antibodies.
Vaccinations are available at community health clinics and have been shown to be safe and effective for young children, the elderly and people with underlying health conditions, such as asthma, diabetes and heart conditions.
In Cambodia, a country of 12 million, 2,026 children aged six months to 15 months have died from the flu since 2008, and 64 children aged one to three have died, according to the latest data from the government.
Health officials have warned of a rise in severe flu cases and the country has already seen a spate of flu, including one child who died last week.
But given the timing, last week’s increase in flu cases was partly due to pre-season preparations, the media reports.
Patients also come from long distances and travel by public transport and that raises the risk of severe illness, because of air pollution and overcrowding.
Image copyright Pixabay Image caption In Singapore, people tend to avoid hospitals unless they have an illness
Some areas of the country are still under a state of emergency and in Singapore the country’s swine flu cases have also risen after low numbers last year.
In Malaysia, which has also faced local flu, the government has urged people to stay at home if they have flu-like symptoms, such as fever and body aches.
In countries like the Netherlands, Italy and Greece, health experts say communities are reluctant to shell out their money to have vaccines given at local clinics for fear they may not benefit from it.
“This is the last year before local clinics in these countries will be able to offer the vaccine locally, because it has been tested for just a few months and has not been approved by national authorities,” said Paola Stanisic from the European Public Health Alliance.
What are the side effects?
Some parents do not take their children to flu clinics because of the risk of rare side effects, such as hearing loss, and conditions like serious allergic reactions, according to critics.
Influenza can sometimes lead to pneumonia, so vaccinations can be used to prevent lung problems.
The vaccine is largely made of dead and weakened virus particles, and a live virus is added in the final steps so the body recognises it as a real influenza infection and produces antibodies to fight it.
How to protect yourself from the flu