For Shawn Broomfield and his wife, there was never a question whether or not to have their four children vaccinated.

Broomfield, a software engineer, and his wife, a veterinarian, trusted in the extensive body of research showing vaccines are safe.

“We never seriously considered [not having them vaccinated],” says the 39-year-old, waiting for his bus in a coffee shop in the southern Washington city of Vancouver in Clark County. “We don’t think the science supports that.”

Not everybody agrees. As Clark County reels from an outbreak of measles that has infected at least 54, almost all of them young children, the community is having to confront some harsh truths – namely that only around 75 per cent of its children are vaccinated, compared to a national average of 92 per cent. Across the state, the figure is 85 per cent.

A combination of anti-vaccine propaganda, a state law that allows parents to opt their children out of being immunised, and a reported cultural suspicion of state medicine among elements of its immigrant population, has made Clark County an anti-vaccination “hotspot”.

The famous faces of the anti-vaccine movement Show all 7 1 /7 The famous faces of the anti-vaccine movement The famous faces of the anti-vaccine movement Charlie Sheen Sheen fought a legal battle against ex-wife Denise Richards to try and block her from vaccinating their children. Richards of course won and Sheen was reportedly so bitter that he paid the paediatrician bill entirely in nickels Getty The famous faces of the anti-vaccine movement Gwyneth Paltrow Paltrow's "health and wellness" company Goop hosted a notorious anti-vaccine speaker at their 2018 Goop Summit Getty The famous faces of the anti-vaccine movement Rob Schneider Schneider demanded the freedom to decline vaccination Getty The famous faces of the anti-vaccine movement Jenny McCarthy McCarthy has claimed that "people are dying from vaccinations", believes that her son caught autism from a vaccine and has pushed her opinions on the topic publicly for many years AFP/Getty The famous faces of the anti-vaccine movement Bill Maher Maher has long spoken against vaccines sating on Larry King live that "a flu shot is the worst thing you can do." His stance appears to stem from a distrust of government AFP/Getty The famous faces of the anti-vaccine movement Alicia Silverstone In Silverstone's book The Kind Mama, she wrote that "there is increasing anecdotal evidence from doctors who have gotten distressed phone calls from parents claiming their child was ‘never the same’ after receiving a vaccine." Getty The famous faces of the anti-vaccine movement Andrew Wakefield Godfather of the anti-vax movement, disgraced doctor Andrew Wakefield famously published a report in the medical journal Lancet claiming a link between the MMR vaccine and autism in 1998. The Lancet retracted the report in 2010 and Wakefield was struck off the medical register PA

Governor Jay Inslee last month declared the outbreak to be a public health emergency. “Measles is a highly contagious infectious disease that can be fatal in small children,” he said.

Dr Alan Melnick, the county health director, is heading efforts to tackle the outbreak.

“There is lot of diversity in our unvaccinated population,” he says. “There is a lot of anti-vaccine propaganda on social media, and some of this stuff is pretty sophisticated. It’s dangerous nonsense.”

He says the fact Washington is one of 17 states that permits parents to object “philosophically” to their children being vaccinated – not just on medical or religious grounds – further compounds the problem.

The quiet city of Vancouver, which sits across the Columbia river from Portland, Oregon, is just the latest community to find itself combatting an outbreak of measles, which is fatal in one to two cases per thousand. The last death from measles in the US was in 2015, but the disease can also cause hearing loss, diarrhoea and swelling of the brain. An outbreak among an Orthodox Jewish population in New York made 2018 the second-worst year for measles since 2000. It is always more perilous for children.

The state Centres for Disease Control and Prevention says online: “In 2018, 349 individual cases of measles were confirmed in 26 states and the District of Columbia. This is the second greatest number of annual cases reported since measles was eliminated in the US in 2000. The greatest was 667 cases reported in 2014.”

Shawn Broomfield and his wife had their four children vaccinated (Andrew Buncombe)

Last November, a North Carolina school with an anti-vaccine community at its heart endured its worst outbreak of chickenpox in more than two decades.

In some of the outbreaks, such as one that struck the Somali-American population of Minneapolis in 2017, experts pointed to the role of disgraced British doctor Andrew Wakefield, as a factor in people’s decision not to have their children vaccinated. Wakefield, who claimed in the 1990s to have found a possible link been the measles, mumps, and rubella vaccination (MMR) and autism, was found guilty of professional misconduct and struck off by the British Medical Council.

In the years since, he has moved to America where he continues to promote his anti-vaccine beliefs. In the case of Washington state, one of the most high-profile anti-vaccine campaigners is Robert F Kennedy Jr, an environmentalist and nephew of the assassinated president John F Kennedy.

The 65-year-old has been leading efforts to block state legislation that would remove parents’ “philosophical” right to object to children being vaccinated if they wanted to attend private or state school. (They could still object on religious or medical grounds.)

John Wiesman, Washington’s health secretary, recently told politicians the proposal was “about safe schools and protecting vulnerable children”.

At least 17 studies have shown no link between autism and the MMR vaccine, but Kennedy continues to argue the contrary. He did not respond to enquiries from The Independent, but according to The News Tribune, he told the meeting of legislators: “We don’t know the risk profile of the MMR vaccine. There is no safety testing for the vaccine.”

Kennedy is a man with powerful connections. In January 2017, he met president-elect Donald Trump, who during a primary debate had falsely claimed vaccines could cause autism.

Kennedy said Trump had asked him to head a commission to investigate their safety. That idea never materialised. However, some of those in Trump’s circle continue to make claims about the dangers of vaccines, despite them being denied by the government’s own scientists.

Andrew Wakefield describes his relationship with Donald Trump

Earlier this month, the wife of White House communications director Bill Shine, Darla Shine, claimed “childhood diseases such as measles keep you healthy and fight cancer”.

She also tweeted: “I had the #Measles #Mumps #ChickenPox as a child and so did every kid I knew - Sadly my kids had #MMR so they will never have the life long natural immunity I have. Come breathe on me!”

In the days since a state of emergency was declared in Washington over measles, residents have reacted in different days. Officials ordered hundreds of children to stay home from school, parents cancelled play-dates and some elderly residents reportedly wore face masks to visit the supermarket. There has also been a 500 per cent increase in the number of vaccinations being provided compared to the same three-month period last year.

Shawn Brannan, of the Sea Mar clinic, says he has seen a jump in the number of parents bringing in their children to be vaccinated. He says a number were from the area’s 40,000-strong Russian and Ukrainian community.

He says he had been told some members of the community are suspicious of state medicine – a holdover from Soviet days – and he had witnessed parents weeping as their children were vaccinated. “Some of them have been in tears,” he says.

Indeed, at least eight of more than 20 outbreak sites in Clark County or Portland were in Slavic churches or schools. “Many Slavic immigrants endured the harshness of the Soviet regime under a totalitarian government,” Yuriy Stasyuk, a data analyst with the Washington Health Alliance, told Komo News. “This has led to a lot of anti-government sentiment and a distrust of academia, science, and public health, which were sponsored by the government.”

Last year, US researchers said Russian social media trolls and bots linked to alleged efforts to meddle in the 2016 presidential election had been pumping anti-vaccine information to “create social discord”.

Researchers, who studied tweets produced by the St Petersburg-based Internet Research Agency, which has been named in indictments filed by special prosecutor Robert Mueller, found it had made claims such there was “a secret government database of vaccine-damaged children”.

David Broniatowski from George Washington University says: “A significant portion of the online discourse about vaccines may be generated by malicious actors with a range of hidden agendas.” It is not known whether the Russian-produced anti-vaccination has been read by people in Clark County.

Peter Tishenko, head pastor of Church of Christ the Saviour, one of the Slavic churches named as an outbreak site, says there is no prohibition against vaccinations. A member of the congregation, who asked not be identified, says both of their children were vaccinated and it was wrong if people in city believed the Russian-speaking community opposed their use. “I know there is a social media frenzy that is going on,” says the church member.

Recently, Hillary Parkin and her 15-month-old son and three-year-old daughter were preparing to dodge the rain as they left a Dollar General store in the north of Vancouver. It is one of three locations of the discount chain listed among the outbreak sites.