There was a broad welcome for the World Health Organisation's declaration of a "public health emergency of international concern" in relation to the Zika virus.
Jonathan Ball, professor of molecular virology at the University of Nottingham, said: "Whilst a direct link between Zika virus infection in pregnancy and babies born with microcephaly needs to be established, the severity of the disease and the strong association with recent and ongoing Zika outbreaks is clearly sufficient cause for concern to declare an international health emergency.
"This makes sense as it will help mobilise international effort and collaboration.
"Regarding the reluctance to impose travel or trade bans, the real difficulty is balancing the risk of further international spread with the needs of the those countries experiencing the worst of the current outbreak.
"A kneejerk response would be to ban travel and trade with countries affected, but the truth is that the potential problem is much wider. It wouldn't really be feasible to lock down the affected countries to try to stop the spread of a virus that is carried by the Aedes mosquito, especially when affected and unaffected countries border one another.
"Until populations can build up sufficient immunity, either through natural infection or through vaccination then the risk to pregnant women is real and therefore this group need to take extra care to avoid becoming exposed."
Professor Trudie Lang, director of the Global Health Network at the University of Oxford, added: "It is excellent news that the WHO have taken this step to make this announcement today. There are many key research questions that must now be addressed in order to understand, manage and ultimately treat and prevent this apparent effect that the Zika virus is having on foetal development during pregnancy.
"This essential research needs to be coordinated, supported and prioritised and this will require rapid international collaboration and strong leadership from a neutral organisation, and this surely must be the WHO rather than any one country?"
Dr Jeremy Farrar, director of the Wellcome Trust, added: "The WHO faced heavy criticism for waiting too long to declare the Ebola outbreak a public health emergency and they should be congratulated for being far more proactive this time. Today's declaration will give the WHO the authority and resources it needs to lead the international response to Zika.
"Research efforts should focus immediately on trying to resolve the many unanswered questions about the infection, including the suspected link with microcephaly as well as determining the true incidence and geographical spread. Armed with this information, the world will be much better placed to develop preventative strategies and control measures to contain the spread of infection within the Americas and beyond.
"There is a long road ahead. As with Ebola, Zika has once again exposed the world's vulnerability to emerging infectious diseases and the devastation they can unleash. Alongside the emergency response that Zika necessitates, we must put in place the permanent reforms, health systems strengthening and proactive research agenda that are needed to make the global health system more resilient to the threat of future pandemics."
Dr Ed Wright, senior lecturer in medical microbiology at the University of Westminster, said: "With 23 countries in the Americas now reporting human cases of Zika virus infection, a prediction of three to four million cases in the next 12 months and the WHO's announcement that it considers this outbreak a 'public health emergency of international concern' due to the possible link to microscopy in newborns, this gives some indication of the potential devastating impact this virus could have.
"This is especially alarming with the outbreak of Ebola in West Africa so fresh in our minds."
However, Dr Wright added: "Towards the end of 2014 it was predicted that the number of Ebola cases could rise to over one million by 2015. But the true number was only a tiny fraction of that. Hopefully the prediction regarding the number of Zika virus cases will be an over-estimation too."
Dr Derek Gatherer, lecturer in the division of biomedical and life sciences at Lancaster University, said: "A PHEIC (public health emergency of international concern) is like a declaration of war, in this case on Zika virus.
"As in real wars, a formal declaration is not necessary for hostilities to begin, and, conversely, formal declarations of war can be followed by periods of "phoney war" where nothing happens.
"The war against Zika has already begun, at street level across Latin America and in many research labs across the world. This is unlikely to be a 'phoney war' from WHO's point of view either."
Dr Gatherer added: "Sensitivity to the criticism of their Ebola response, where the PHEIC only came nine months into the outbreak, means that we can expect to see some vigorous activity in the coming months."
Professor Michael Bonsall, professor of mathematical biology at University of Oxford, added: "Now that microcephaly associated with Zika has been declared as a PHEIC by the WHO it warrants immediate and swift action. I agree with all the points raised by the WHO."