Tag: travel alert

When is Measles Season?

For a while, especially once we eliminated the endemic spread of measles, we weren’t thinking about measles seasons anymore.

In addition to the recent rise in measles cases, this slide shows the patterns of measles seasons in different parts of the world.
In addition to the recent rise in measles cases, this slide shows the patterns of measles seasons in different parts of the world.

Unfortunately, with ongoing outbreaks and rising cases, many people are asking again – just when is measles season?

When is Measles Season?

Traditionally, the time when measles case counts are the highest occurs:

  • during the late winter and early spring (temperate climates, like the United States)
  • after the rainy season (tropical climates)
  • when kids are in school

So just like flu season, it’s always measles season somewhere…

And in areas of the world where measles is still highly endemic, you can expect cycles of larger measles epidemics every 1 to 4 years.

Can you guess why?

“As higher uniform population immunity is achieved the scale of epidemics, both their duration and absolute number of cases, progressively decreases. Epidemic frequency simultaneously decreases with increasing time intervals between epidemics. Another uniform feature as elimination is approached is the loss of epidemic seasonality.”

Durrheim et al on Measles – The epidemiology of elimination

I’ll give you a hint – there is nothing different about the measles virus during those years.

Eventually though, as the number of people susceptible to measles builds up, there is the opportunity for bigger outbreaks. Of course, that doesn’t happen if most people are vaccinated and protected.

When is Measles Season in the United States?

What about in the United States in the post-vaccine era?

Visiting a place with a lot of measles, especially if you aren't vaccinated and protected, increases the risk that you will bring measles home with you and start an outbreak.
Visiting a place with a lot of measles, especially if you aren’t vaccinated and protected, increases the risk that you will bring measles home with you and start an outbreak.

We don’t really have a measles season, as all of our cases are now imported from other parts of the world.

  1. Where and when are folks traveling?
  2. Where is measles on the rise?

That’s when we will see more measles cases here.

“Source countries included Philippines (14 cases), Ukraine (8), Israel (5), Thailand (3), Vietnam (2), Germany (2), and one importation each from Algeria, France, India, Lithuania, Russia, and the United Kingdom.”

Increase in Measles Cases — United States, January 1–April 26, 2019

In the early part of 2019, we saw a lot of cases because unvaccinated travelers were returning from Philippines, Ukraine, and Israel, countries in peak measles season.

Are Europe's measles outbreaks slowing down yet?
Are Europe’s measles outbreaks slowing down yet?

As cases in those countries hopefully slow down over the summer, unfortunately, we might see a rise in other parts of the world.

Of course, there is an easy way to end our measles seasons once and for all.

Two doses of MMR is your best protection against measles.

Get vaccinated and protected, especially before traveling out of the country.

More on Measles Season?

Mapping the 2019 Measles Outbreaks

Cases of measles continue to rise, as we pass 1,000 cases in the United States.

2019 Measles Outbreaks

With a record high number of cases, there are measles cases and outbreaks in 31 states, including:

Alaska1Massachusetts2
Arizona1Michigan44
California61Mississippi1
Colorado1Missouri2
Connecticut3Nevada1
Florida2New Hampshire1
Georgia3New Jersey13
Hawaii2New York804
Idaho2Ohio1
Illinois7Oklahoma4
Indiana1Oregon11
Iowa2Pennsylvania6
Kentucky2Tennessee3
Maine1Texas20
Maryland4Virginia1
Washington85

What’s the first thing you notice about this measles outbreaks?

Where Are the Measles Outbreaks

They aren’t spread out evenly through the United States.

A simple tilegram of the United States.
A simple tilegram of the United States.

In fact, the largest outbreaks are clustered in just a few states, including California, Michigan, New York (Rockland County and Brooklyn), and Washington (Pacific Northwest Outbreak and the Puget Sound Outbreak).

Mapping the 2019 Measles Outbreaks

What does that look like when you map it?

It looks a little strange…

A tilegram mapping the 2019 measles outbreaks in the United States.

And that’s because, amazingly, about 70% of cases this year are in just one state – New York!

But that doesn’t mean that you don’t have to be concerned if you don’t live in New York. After all, measles is on the rise all over the world and it is still just a plane ride away. And there are plenty of other communities with low immunization rates where folks are at risk for outbreaks.

Also consider that even without the big outbreaks, this would still rank as a big year for measles.

Bottom line?

Get vaccinated and protected and stop the outbreaks. The MMR vaccine is safe, effective, with few risks. And it is obviously necessary.

More on Mapping the 2019 Measles Outbreaks

Is Measles Still Eliminated in the United States?

Do you remember when measles was eliminated in the United States?

You probably should.

Remember when we eliminated measles and we used to only have about 100 cases of measles in the United States each year?
Remember when we eliminated measles and we used to only have about 100 cases of measles in the United States each year? Pensacola News Journal July 2000

It wasn’t that long ago…

When Measles Was Eliminated in the United States

After several years of declining numbers of measles outbreaks in the United States, the endemic spread of measles was declared eliminated in March 2000.

“The data indicated that, during 1997–1999, measles incidence has remained low (<0.5 cases per 1,000,000 population) and that most states and 99% of counties reported no measles cases. In addition, measles surveillance was sensitive enough to consistently detect imported cases, isolated cases, and small outbreaks. Evidence of high population immunity included coverage of >90% with the first dose of measles vaccine in children aged 19–35 months since 1996 and 98% coverage among children entering school. In 48 states and the District of Columbia, a second dose of measles vaccine is required for school entry. A national serosurvey indicated that 93% of persons aged >6 years have antibody to measles.”

Measles — United States, 1999

What did that mean?

It is easy to understand when you note that we still had 86 cases of measles in the United States that year.

So, measles wasn’t gone yet. It was just that most cases were imported from outside the country. Only imported strains of the measles virus were causing outbreaks.

“The end of endemic measles transmission in the United States has both domestic and international importance. Domestically, the absence of endemic exposure to measles means few persons in the United States will be infected and risk complications of measles. This decreased risk of exposure provides protection to groups not protected directly by vaccination: children too young for routine vaccination; the few persons who, although vaccinated, are not protected, primarily from failure to mount an adequate response to vaccine; persons for whom vaccine is contraindicated (e.g., those with immunodeficiency); and persons who choose not to be vaccinated.”

Wharton on Measles Elimination in the United States

Unfortunately, the “choose not to be vaccinated” group might be endagering our claim to have eliminated measles.

Is Measles Still Eliminated in the United States?

As we break more and more measles records this year, it would be easy to just say that the endemic spread of measles is no longer eliminated in the United States.

“Endemic measles transmission is the existence of any continuous indigenous chain of transmission of measles virus that persists for >1 year in any defined geographic area (e.g., the United States).”

Orenstein on Defining and Assessing Measles Elimination Goals

Still, when you look at the numbers, technically, measles isn’t yet spreading endemically in the United States.

Although we are seeing measles cases in 27 states, about 70% of them are in just two outbreaks in one state - New York.
Although we are seeing measles cases in 27 states, about 70% of them are in just two outbreaks in one state – New York.

We are getting close though.

The outbreaks in Rockland County and Brooklyn started in September and October 2018. If they aren’t stopped soon, will it be easier to make a case that measles is no longer eliminated in the United States?

“Outbreaks in New York City and Rockland County, New York have continued for nearly 8 months. If these outbreaks continue through summer and fall, the United States may lose its measles elimination status.”

U.S. measles cases in first five months of 2019 surpass total cases per year for past 25 years

It sounds like it.

One thing to consider though, after an unvaccinated visitor introduced measles to Brooklyn from Israel back in October, measles has been reintroduced into the community at least seven other times! This includes travelers from Israel, UK, and Ukraine.

So the outbreak isn’t necessarily a “continuous indigenous chain of transmission of measles virus.”

It is multiple chains in the same community.

“There have been additional cases of measles from international travelers to Rockland, exposing more people to measles.”

2018 – 2019 Measles Outbreak in Rockland County

The same thing has happened in Rockland County after the initial importation from Israel in September.

Measles Elimination Criteria

Does that matter?

It likely should, but let’s also look at how we do with other criteria that are often used to assess the absence of the endemic spread of measles:

  • Few measles cases/low measles incidence – we will have the most cases in 2019 since 1992, but most cases are clustered in just a few big outbreaks
  • The duration of outbreaks is short – outbreaks are getting longer and harder to contain, but part of the problem is the global rise in measles and the reintroduction of measles into existing outbreaks
  • Most cases are associated with international importation – still very true
  • No endemic measles virus strain – outbreaks this year have been associated with strains that are commonly seen in Ukraine, the Philippines, and a few other areas
  • Long periods with no unknown-source cases – most cases are linked to international travel
  • High population immunity – except for pockets of susceptibles, folks who intentionally don’t vaccinate their kids or get themselves vaccinated, we do have high population immunity
  • Low levels of transmission from reported cases – in most outbreaks, that it is still true, unfortunately, there are more outbreaks this year
  • Adequate measles surveillance system – definitely true

What is the best argument that the endemic spread of measles has still been eliminated in the United States?

“A small number of cases have occurred outside of these neighborhoods but have, to date, not resulted in sustained transmission of measles.”

Measles Cases Rise to 466 Including in Two Unvaccinated Children Spending Time in Areas with Measles Activity

Even where there are big outbreaks, measles isn’t spreading outside of very specific communities of intentionally unvaccinated children and adults.

And that’s because most people are vaccinated and protected and aren’t letting measles spread endemically!

Losing Measles Elimination Status

If we did lose our status of having eliminated measles, we wouldn’t be the first.

“As of 30 June 2018, measles transmission in Venezuela has been ongoing for over one year. Therefore, endemic transmission of measles is considered to have been reestablished in Venezuela.”

Fourth ad hoc Meeting of the Technical Advisory Group (TAG) on Vaccine-preventable Diseases

Tragically, since their outbreaks began a few years ago, there have been nearly 10,000 cases and at least 78 deaths. Cases have also spread to many other countries in South America.

Venezuela isn’t the only country where we have seen the return of measles though.

In 2017, the European regional verification commission verified the reestablishment of the endemic spread of measles in the Russian Federation and in Germany.

“Countries in all six WHO regions have adopted goals for measles elimination by 2020.”

Progress Toward Regional Measles Elimination — Worldwide, 2000–2017

Surprisingly, some other countries in Europe, like Belgium, France, and Italy, never eliminated measles.

What’s next?

Hopefully, instead of a new normal, the rise in cases gets us back on track to eliminating and one day eradicating measles.

More on When Measles Was Eliminated in the United States

What’s Your Chance of Getting Measles Right Now?

It shouldn’t be a surprise that a lot of folks are thinking about their risk of getting measles right now.

But with record levels of measles cases this year, some of us are thinking about our level of risk much differently than others.

rIf you are unvaccinated and exposed to someone with measles, you risk is actually 1,000,000 times higher…

While most of us simply want to make sure we are vaccinated and protected, anti-vaccine folks are taking every opportunity to downplay their risks.

What’s Your Chance of Getting Measles Right Now?

So what’s your chance of getting measles?

“Measles is one of the world’s most contagious diseases. It is spread by coughing and sneezing, close personal contact or direct contact with infected nasal or throat secretions. The virus remains active and contagious in the air or on infected surfaces for up to 2 hours. It can be transmitted by an infected person from 4 days prior to the onset of the rash to 4 days after the rash erupts.”

WHO on Measles

That’s actually not that simple to figure out, but depends on:

Those who have had two doses, with no plans to travel, and who live in an area with no reported cases, are at extremely low risk to get measles – the risk won’t be zero until measles is eradicated.

In this kind of low risk situation, kids don’t need early doses of MMR vaccines and most adults can probably get away with just having one dose of MMR.

“Measles is highly contagious and spreads through the air when an infected person coughs or sneezes. It is so contagious that if one person has it, 9 out of 10 people of all ages around him or her will also become infected if they are not protected.”

CDC on Measles is Highly Contagious

On the other hand, if you are unvaccinated and were at the AMC Theater on Lemon Street in Fullerton, between 11 p.m. and 4 a.m. on April 25, then your chance of getting measles is about 90%!

Wait! That’s a little more than the 0.000092% chance that anti-vaccine folks are throwing around…

The odds of being hit by lightning are low because we practice storm safety and don’t run around outside when we see lightning!

To think of it another way, if you knew that your chances of getting hit by lightning were a little over 1 in a million, would that make you think it is okay to go outside and play golf during a severe thunderstorm?

Would you think the risk is so low that you could let your kids play outside if you heard thunder and saw lightning flashes nearby, or would you all rush inside?

That’s right! The risk of getting hit by lightning is low because most of us don’t take chances when we hear thunder or see lightning.

It’s the same with measles and other vaccine-preventable diseases.

The overall risk is low because most people are vaccinated and protected!

If you aren’t vaccinated and protected, as we see more and more cases, your risk of getting sick, and getting others sick, is going to continue to get higher and will always be much higher than someone who is fully vaccinated, no matter how much you want to believe in shedding, mild measles, or whatever myths help you justify keeping your kids unvaccinated and unprotected during an outbreak.

Remember, you can’t hide in the herd if you are scaring away too much the herd

Vaccines are safe, with few risks, and are obviously necessary.

You can avoid getting measles.
You can greatly reduce your family’s risk of getting measles.

Make sure your family is protected so they don’t get caught up in a measles outbreak

More on Your Chance of Getting Measles