LONDON (Reuters) - At least 12 groups are now working to develop a Zika vaccine and health authorities said on Monday they were working to ensure development proceeded as rapidly as possible.

A medical researcher works on results of tests for preventing the spread of the Zika virus and other mosquito-borne diseases at the Gorgas Memorial institute for Health Studies laboratory in Panama City February 5, 2016. REUTERS/Carlos Jasso

The World Health Organization said it was important to establish speedy regulatory pathways, although all the vaccines remained in early-stage development and licensed products would take “a few years” to reach the market.

With no approved Zika vaccines or medicines and none even undergoing clinical studies, scientists and drugmakers are on the starting-block in fighting the mosquito-borne disease suspected of causing a spike in birth defects in Brazil.

However, Zika is similar to dengue, yellow fever and West Nile virus, for which vaccines exist or are being developed, and the hope is to try similar approaches against the latest hazard.

The London-based European Medicines Agency (EMA) said it had established an expert task force on Zika to advise companies working on vaccines and medicines, mirroring similar action during Ebola and pandemic flu outbreak in 2009.

“The agency is encouraging medicines developers to contact EMA if they have any promising projects in this area. EMA will also proactively reach out to companies already planning to work on investigational vaccines and offer scientific and regulatory advice,” it said in a statement.

“Early and regular interaction with the agency can significantly speed up the development of medicines.”

President Barack Obama will also ask the U.S. Congress for more than $1.8 billion in emergency funding to fight the virus, the White House said.

Several biotech and pharmaceutical companies are racing to develop a Zika vaccine, including France’s Sanofi, which already has vaccine for dengue.

But scientists know relatively little about Zika and the road to developing a preventative shot against the disease is strewn with hurdles - not least because the group viewed as most at risk are pregnant women.

Some research is also being done on prophylactic medicines against Zika, which would work in the same way as drugs to stop people catching malaria.

The development of better diagnostic tests is another high priority. Currently, it is hard to differentiate Zika from other similar so-called flaviviruses, such as dengue.

The WHO said diagnostics were “a top urgency”. It issued a call to interested companies on Feb. 5 to submit potential products for emergency quality assessment, so that successful tests could be put to use quickly.