India became free of polio earlier this year, but it is 'difficult' to eradicate it completely across the globe by the target year of 2018 set by the Global Polio Eradication Initiative (GPEI), according to a leading expert in the field.
Currently, the three countries yet to eradicate polio are Pakistan, Afghanistan and Nigeria, where health professionals face considerable challenges, particularly in Pakistan, where some elements oppose vaccination because they associate it with a foreign science.
Emmanuel Vidor, a global expert in polio prevention and associate vice-president of vaccines giant Sanofi Pasteur, told a group of visiting journalists here that eradicating polio in India was a 'big achievement', but meeting GPEI's 2018 target was "difficult".
Last week, Prime Minister Narendra Modi announced that India would add an injectable vaccine to the national health programme as it would provide extra protection against reappearance of the disease in India.
Most of the world's injectable polio vaccine is produced in a new precision building on the Sanofi Pasteur complex that is reaching full production capacity after 10 years of construction, testing and scale-up.
In line with WHO guidelines, the injectable polio vaccines are increasingly used by countries due to its ability to eliminate the risk of vaccine-associated paralytic poliomyelitis that sometimes occurs with the use of oral vaccine.
Given security and other challenges to immunisation plans in Pakistan and people travelling across the border, Pakistan poses a risk to India, including the spectre of bio-terrorism, since a vial of live polio virus can affect an entire population.
Vidor said: "the situation in Pakistan is of concern, more cases of polio are being reported every day, it is deteriorating".
Sanofi Pasteur, which traces its origins to the iconic French microbiologist Louis Pasteur, produces vaccines for a range of diseases, but is best known for its oral and injectable vaccines for polio.