(CNN) An outbreak of measles is spreading across Italy, with more than 1,600 cases of the disease reported in 2017, across 19 of the country's 21 regions.

The number of cases seen so far this year is already higher than the total number of cases seen during all of 2016, according to the European Centers for Disease Control.

The outbreak adds to concern among European health officials who have been monitoring an ongoing outbreak in Romania, where almost 4,800 cases have been reported since the start of 2016. The country has also seen 21 deaths, according to the World Health Organization

"Italy is one of two main countries affected across the (European) region at the moment," said Dr. Robb Butler, Program Manager of the Vaccine-preventable Diseases and Immunization Program of the WHO Regional Office for Europe.

The United Stated Centers for Disease Control and Prevention has now issued recommendations for anyone traveling to Italy to ensure they are vaccinated against measles. Recommendations for travel to Romania have been in place since 2016.

The Americas were declared measles-free in 2016, something the European region of WHO is still working towards.

Almost 40% of cases in Italy were admitted into hospital and the median age of those affected was 27 years, according to the country's Ministry of Health

The European Center for Disease Control state most cases were in patients older than 15 years of age, meaning babies and young children are not the ones becoming infected but instead people who failed to be vaccinated as children.

"Italy has had suboptimal coverage for many years now," said Butler, adding that vaccine coverage for measles has fallen every year since 2012. The country saw a large outbreak in 2014, when 4,350 people were infected.

Of the 1,603 cases reported this year, as of April 16, 88% are known to be unvaccinated.

More than 95% of the population need to be vaccinated for the measles virus not to persist within a population, known as the herd immunity threshold. In 2015, WHO data shows coverage in Italy at 83% for those who received a second dose of a measles vaccine. Some regions within Italy are as low as 70%, said Butler.

Butler believes the fall in confidence towards vaccines is fueled by both a rise in the anti-vaccine movement across Europe as well as complacency towards the disease, with some not receiving vaccinations due to lack of concern about the risk of contracting measles.

"Parents are under the impression measles cases have been consigned to history," he said. "Until they see an outbreak."

But he is more worried about the increasing refusal of the vaccine by people fearing adverse effects, which stems as far back as the MMR scare ignited by a now discredited and retracted paper published by UK scientist Andrew Wakefield. "We have seen vaccine refusal increasing," said Butler.

"Our advise is clear: everyone should be vaccinated," he said.

While negative attitudes are also playing a role in Romania's ongoing epidemic, experts add the country's health system, and it's inability to reach everyone in the population has an equally crucial part to play in the outbreak. "Vaccines are in good supply ... but a large percentage of the population are hard to reach," said Butler. Officials in Romania, however, are currently reporting temporary supply issues for measles containing vaccines which have slightly stalled their response.

There are 630,000 registered Roma in Romania and many more unregistered that are under-served by the system and need particular attention, said Butler.

"There's a convergence of these different concerns," said Heidi Larson, Director of the Vaccine Confidence Project at the London School of Hygiene & Tropical Medicine. "But the main issue is safety anxieties."

Falling confidence, rising infections

In 2016, Larson led a study exploring the state of vaccine confidence across 67 countries worldwide in which people were asked four simple questions: whether vaccines were important, safe, effective and compatible with their religious beliefs.

"(Italy) was the second worst in the world, second only to France," in terms of negativity towards vaccines, said Larson.

Approximately 20% of those surveyed in Italy (20.6%) and Romania (19.8%) disagreed with the statement that vaccines were safe. In France, more than 40% disagreed, while the global average was 13%, said Larson. France has also experienced a measles outbreak this year.

"Measles is the first thing you will see after non-vaccination, said Larson. "Because it's so highly infectious."

Larson fears that anti-vaxxers in positions of power will further aid these outbreaks by increasing uncertainty and anxiety among populations and feels that those in support of vaccines now need to be more vocal, like their opposition.

"We shouldn't ignore it," she said, adding that health professionals and public health officials should have conversations with people and not be dismissive of their concerns.

Dr. Andrea Ammon, European Centers for Disease Control acting director, said: "It is worrying to see the accumulation of unvaccinated individuals and as a consequence outbreaks of measles in several European countries, particularly considering the availability of a highly effective and safe vaccine against the disease."

What's being done

Health officials within Italian and Romanian departments of health as well as the WHO and European Centers for Disease Control are working to control the current outbreaks.

"Opportunities for the identification of unvaccinated individuals and catch-up vaccination need to be reinforced," said Ammon. "Closing immunisation gaps in adolescents and adults who did not receive vaccination in the past, as well as strengthening routine childhood immunisation programmes, are vital to prevent future outbreaks and ensure adequate levels of protection."

Join the conversation See the latest news and share your comments with CNN Health on Facebook and Twitter.

In Romania, large-scale vaccination campaigns are underway to reach those who remain unvaccinated. "These are driving people towards immunization sites," said Butler.

In Italy, national vaccination campaigns are not underway but there is national support to increase investment and communication of the importance of getting vaccinated to protect populations. "They need to reach underperforming regions," said Butler.

While confident that the increased investment and campaigns in Romania are a step in the right direction to control that country's outbreak, Butler admits controlling the epidemic in Italy is a "tough job."

"We are in a very vulnerable place," added Larson, believing officials must not drop the ball on public confidence. "If we resist and say this is still fringe, we risk losing."