So far, so good.

Three weeks since a programme to vaccinate a million children against dengue by June began, the Philippines has reached nearly one-sixth of its target.

More importantly, only a fraction of those who have been given the vaccine are showing adverse effects such as fever, headaches and dizzy spells.

It is too early to tell if the vaccine Dengvaxia, manufactured by French drugmaker Sanofi, is effective and safe enough for everyone to use.

But initial results are encouraging for nations in Asia and Latin America where dengue, a mosquito-borne disease that afflicts some 390 million globally each year, is widespread.

Last week, the Philippine Health Ministry reported that 148,431 fourth-grade pupils in 44 public schools had received the first dose of Dengvaxia. Only 240 children - 0.16 per cent - suffered side effects.

A World Health Organisation (WHO) expert group has recommended the use of the vaccine, based on a review of data from 25 clinical studies in 15 countries. Dengvaxia protected two-thirds of people against dengue in those aged nine or older in two large clinical trials in Asia and Latin America involving more than 40,000 children and adolescents. It was most effective at protecting against severe dengue, which could be fatal. The WHO's recommendations have silenced critics here who said the Health Ministry might have been too eager to use the vaccine on so many children.

Still, concerns remain.

Public health advocates warn that the vaccine may increase dengue's severity, a phenomenon known as "antibody dependent enhancement", three years down the road. Vaccination programmes also do not come cheap, especially for nations with small healthcare budgets.

For now, though, the consensus here has been that it is still far better to do something now than to just wait and do nothing at all.