The World Health Organization (WHO) declared the end of the epidemic in November 2016, but noted that the virus still represents "a highly significant and long term problem".

In February 2016, the WHO declared the outbreak a Public Health Emergency of International Concern as evidence grew that Zika can cause birth defects as well as neurological problems.

As early as August 2014, physicians in Natal, in northeastern Brazil began to investigate an outbreak of illness characterized by a flat pinkish rash, bloodshot eyes, fever, joint pain and headaches.

[78][85] However, the outbreak in French Polynesia is known to have peaked and declined precipitously by February 2014, lending doubt to the suggestion the virus arrived later that year in Brazil with spectators and competitors.

[104] It is difficult to diagnose Zika virus infection based on clinical signs and symptoms alone due to overlaps with other arboviruses that are endemic to similar areas.

[111] On January 15, 2016, because of the "growing evidence of a link between Zika and microcephaly" the Centers for Disease Prevention and Control (CDC) issued a travel warning advising pregnant women to consider postponing travel to Brazil as well as the following countries and territories where Zika fever had been reported: Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and the Commonwealth of Puerto Rico.

[113] On January 22, eight more countries and territories were added to the list of those affected: Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde, and Samoa.

[128] By mid-August at least 37 people had contracted the virus in neighborhoods near the city of Miami, Florida, though officials estimated that the actual number of infections was much higher due to under-reporting of mild illness.

[citation needed] On October 17, Zika was declared as endemic in Vietnam by the country Health Ministry due to the number of local cases.

[146] The government of the republic hosting the "One Philippines against Zika" national summit on October 28 with church in the country has joint fight to curb the spread of the virus by issuing a pastoral guidance to help raise awareness about the mosquito-borne disease among local communities.

[98][168] Furthermore, the Centers for Disease Control and Prevention (CDC) recommends that containers holding water near homes either be sealed or scrubbed once per week, because mosquito eggs can stick to them.

[99] On February 1, 2016, WHO declared the cluster of microcephaly cases and other neurological disorders a Public Health Emergency of International Concern,[6] which may reduce the number of visitors to the Rio Olympics in 2016.

The committee reported that evidence was increasing for a causal relationship between Zika virus and microcephaly and other neurological conditions, and called for continued research, aggressive mosquito control, and improved surveillance and communication of risks to the public.

[171] On March 9, 2016, WHO announced that research should prioritise prevention and diagnosis, not treatment, and in particular non-live vaccines suitable for pregnant women and those of childbearing age, novel mosquito control measures, and diagnostic tests that can detect dengue and chikungunya as well as Zika.

[172] In January 2016, it was announced that, in response to the Zika virus outbreak, Brazil's National Biosafety Committee approved the releases of more genetically modified Aedes aegypti mosquitoes throughout their country.

[173] Previously, in July 2015, Oxitec had published results of a test in the Juazeiro region of Brazil, of so-called "self-limiting" mosquitoes, to fight dengue, chikungunya, and Zika viruses.

[182] In February, the Brazilian federal government mobilized 60% of the country's Armed Forces, or about 220,000 soldiers, to warn and educate the populations of 350 municipalities on how to reduce mosquito breeding grounds.

[186] In February 2016, Google announced that they were donating $1 million via UNICEF to fight the spread of the Zika virus and offering professional personnel to help to determine where it will hit next.

Dr Ed Wright, a senior lecturer and virologist at the University of Westminster, said: "All of the vaccines currently under development are many years away from being licensed and available for widespread public use."

Jonathan Ball, professor of molecular virology at the University of Nottingham, said: "We knew that these vaccines worked in mice and now the researchers have shown that they also protect non-human primates from Zika virus infection."

"We are eager to expand testing of our broad spectrum antivirals in Zika virus as they have shown compelling efficacy across other flaviviruses such as Dengue and West Nile and have the potential for long-term development.

Recent outbreaks have been connected to an alarming a spike in microcephaly, a birth defect that inhibits the proper development of a baby's brain, and Guillain-Barré syndrome, which causes paralysis.

[194] Other challenges include the lack of a safe and effective vaccine, a complicated diagnostic process, and faltering support for research funding in the federal government.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), said "There aren't any federally licensed vaccines or specific therapeutics currently available to prevent or treat Zika."

[200] On February 16, 2016, the Vatican condemned the UN for its call to action, deeming it "an illegitimate response" to the Zika crisis and emphasizing that "a diagnosis of microcephaly in a child should not warrant a death sentence".

[201] On February 18, 2016, after a trip to Latin America, Pope Francis stated that "avoiding pregnancy is not an absolute evil" in cases such as the Zika virus outbreak.

[203] The epidemic also caused a rise in tweets from college students upset that their spring break trips and study abroad plans had been changed or cancelled due to the virus' spread.

[204] The same study also found that tweets from reputable institutions and people holding scientific credentials demonstrated the ability of Twitter as a source to spread information quickly on the internet.

[212] Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases said that the NIAID was running out of funds, which would substantially slow down the development of vaccines.

[214] Senate Democrats urged Republicans to approve the full amount of funding more quickly rather than waiting for major transmission of Zika virus to begin in the United States.