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Retaining flavor while removing caffeine − a chemist explains the chemistry behind decaf coffee

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theconversation.com – Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami University – 2024-07-23 07:13:15

Several processes can take most of the caffeine out of coffee.
AP Photo/John Minchillo

Michael W. Crowder, Miami University

For many people, the aroma of freshly brewed coffee is the start of a great day. But caffeine can cause headaches and jitters in others. That’s why many people reach for a decaffeinated cup instead.

I’m a chemistry professor who has taught lectures on why chemicals dissolve in some liquids but not in others. The processes of decaffeination offer great real-life examples of these chemistry concepts. Even the best decaffeination method, however, does not remove all of the caffeine – about 7 milligrams of caffeine usually remain in an 8-ounce cup.

Producers decaffeinating their coffee want to remove the caffeine while retaining all – or at least most – of the other chemical aroma and flavor compounds. Decaffeination has a rich history, and now almost all coffee producers use one of three common methods.

All these methods, which are also used to make decaffeinated tea, start with green, or unroasted, coffee beans that have been premoistened. Using roasted coffee beans would result in a coffee with a very different aroma and taste because the decaffeination steps would remove some flavor and odor compounds produced during roasting.

The carbon dioxide method

In the relatively new carbon dioxide method, developed in the early 1970s, producers use high-pressure CO₂ to extract caffeine from moistened coffee beans. They pump the CO₂ into a sealed vessel containing the moistened coffee beans, and the caffeine molecules dissolve in the CO₂.

Once the caffeine-laden CO₂ is separated from the beans, producers pass the CO₂ mixture either through a container of water or over a bed of activated carbon. Activated carbon is carbon that’s been heated up to high temperatures and exposed to steam and oxygen, which creates pores in the carbon. This step filters out the caffeine, and most likely other chemical compounds, some of which affect the flavor of the coffee.

These compounds either bind in the pores of the activated carbon or they stay in the water. Producers dry the decaffeinated beans using heat. Under the heat, any remaining CO₂ evaporates. Producers can then repressurize and reuse the same CO₂.

This method removes 96% to 98% of the caffeine, and the resulting coffee has only minimal CO₂ residue.

This method, which requires expensive equipment for making and handling the CO₂, is extensively used to decaffeinate commercial-grade, or supermarket, coffees.

Swiss water process

The Swiss water method, initially used commercially in the early 1980s, uses hot water to decaffeinate coffee.

Initially, producers soak a batch of green coffee beans in hot water, which extracts both the caffeine and other chemical compounds from the beans.

It’s kind of like what happens when you brew roasted coffee beans – you place dark beans in clear water, and the chemicals that cause the coffee’s dark color leach out of the beans into the water. In a similar way, the hot water pulls the caffeine from not yet decaffeinated beans.

During the soaking, the caffeine concentration is higher in the coffee beans than in the water, so the caffeine moves into the water from the beans. Producers then take the beans out of the water and placed them into fresh water, which has no caffeine in it – so the process repeats, and more caffeine moves out of the beans and into the water. The producers repeat this process, up to 10 times, until there’s hardly any caffeine left in the beans.

The resulting water, which now contains the caffeine and any flavor compounds that dissolved out from the beans, gets passed through activated charcoal filters. These trap caffeine and other similarly sized chemical compounds, such as sugars and organic compounds called polyamines, while allowing most of the other chemical compounds to remain in the filtered water.

Producers then use the filtered water – saturated with flavor but devoid of most of the caffeine – to soak a new batch of coffee beans. This step lets the flavor compounds lost during the soaking process reenter the beans.

YouTube video
This animation shows the steps to the Swiss water process.

The Swiss water process is prized for its chemical-free approach and its ability to preserve most of the coffee’s natural flavor. This method has been shown to remove 94% to 96% of the caffeine.

Solvent-based methods

This traditional and most common approach, first done in the early 1900s, uses organic solvents, which are liquids that dissolve organic chemical compounds such as caffeine. Ethyl acetate and methylene chloride are two common solvents used to extract caffeine from green coffee beans. There are two main solvent-based methods.

In the direct method, producers soak the moist beans directly in the solvent or in a water solution containing the solvent.

The solvent extracts most of the caffeine and other chemical compounds with a similar solubility to caffeine from the coffee beans. The producers then remove the beans from the solvent after about 10 hours and dry them.

In the indirect method, producers soak the beans in hot water for a few hours and then take them out. They then treat the water with solvent to remove caffeine from the water. Methylene chloride, the most common solvent, does not dissolve in the water, so it forms a layer on top of the water. The caffeine dissolves better in methylene chloride than in water, so most of the caffeine stays up in the methylene chloride layer, which producers can separate from the water.

A diagram showing some of the ways to decaffeinate coffee.
A few chemical processes can remove the caffeine from coffee beans.
Andy Brunning/Compound Interest, CC BY-NC

As in the Swiss water method, the producers can reuse the “caffeine-free” water, which may return some of the flavor compounds removed in the first step.

These methods remove about 96% to 97% of the caffeine.

Is decaf coffee safe to drink?

One of the common solvents, ethyl acetate, comes naturally in many foods and beverages. It’s considered a safe chemical for decaffeination by the Food and Drug Administration.

The FDA and the Occupational Safety and Health Administration have deemed methylene chloride unsafe to consume at concentrations above 10 milligrams per kilogram of your body weight. However, the amount of residual methylene chloride found in roasted coffee beans is very small – about 2 to 3 milligrams per kilogram. It’s well under the FDA’s limits.

OSHA and its European counterparts have strict workplace rules to minimize methylene chloride exposure for workers involved in the decaffeination process.

After producers decaffeinate coffee beans using methylene chloride, they steam the beans and dry them. Then the coffee beans are roasted at high temperatures. During the steaming and roasting process, the beans get hot enough that residual methylene chloride evaporates. The roasting step also produces new flavor chemicals from the breakdown of chemicals into other chemical compounds. These give coffee its distinctive flavor.

Plus, most people brew their coffee at between 190 F to 212 F, which is another opportunity for methylene chloride to evaporate.

Retaining aroma and flavor

It’s chemically impossible to dissolve out only the caffeine without also dissolving out other chemical compounds in the beans, so decaffeination inevitably removes some other compounds that contribute to the aroma and flavor of your cup of coffee.

But some techniques, like the Swiss water process and the indirect solvent method, have steps that may reintroduce some of these extracted compounds. These approaches probably can’t return all the extra compounds back to the beans, but they may add some of the flavor compounds back.

Thanks to these processes, you can have that delicious cup of coffee without the caffeine – unless your waiter accidentally switches the pots.The Conversation

Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Coastal economies rely on NOAA, from Maine to Florida, Texas and Alaska – even if they don’t realize it

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theconversation.com – Christine Keiner, Chair, Department of Science, Technology, and Society, Rochester Institute of Technology – 2025-02-28 07:46:00

Coastal economies rely on NOAA, from Maine to Florida, Texas and Alaska – even if they don’t realize it

U.S. fishing industries, both commercial and recreational, rely on healthy coastal areas.
Wolfgang Kaehler/LightRocket via Getty Images

Christine Keiner, Rochester Institute of Technology

Healthy coastal ecosystems play crucial roles in the U.S. economy, from supporting multibillion-dollar fisheries and tourism industries to protecting coastlines from storms.

They’re also difficult to manage, requiring specialized knowledge and technology.

That’s why the National Oceanic and Atmospheric Administration – the federal agency best known for collecting and analyzing the data that make weather forecasts and warnings possible – leads most of the government’s work on ocean and coastal health, as well as research into the growing risks posed by climate change.

The government estimates that NOAA’s projects and services support more than one-third of the nation’s gross domestic product. Yet, this is one of the agencies that the Trump administration has targeted, with discussions of trying to privatize NOAA’s forecasting operations and disband its crucial climate change research.

As a marine environmental historian who studies relationships among scientists, fishermen and environmentalists, I have seen how NOAA’s work affects American livelihoods, coastal health and the U.S. economy.

Here are a few examples from just NOAA’s coastal work, and what it means to fishing industries and coastal states.

Preventing fisheries from collapsing

One of the oldest divisions within NOAA is the National Marine Fisheries Service, known as NOAA Fisheries. It dates to 1871, when Congress created the U.S. Commission of Fish and Fisheries. At that time, the first generation of conservationists started to worry that America’s natural resources were finite.

By conducting surveys and interviewing fishermen and seafood dealers, the fish commissioners discovered that freshwater and saltwater fisheries across the country were declining.

YouTube video
Looking back on 150 years of NOAA’s fisheries history.

Oil spills and raw sewage were polluting waterways. Fishermen were using high-tech gear, such as pound nets, to catch more and more of the most valuable fish. In some areas, overfishing was putting the future of the fisheries in jeopardy.

One solution was to promote aquaculture, also known as fish or shellfish farming. Scientists and entrepreneurs reared baby fish in hatcheries and transferred them to rivers, lakes or bays. The Fish Commission even used refrigerated railroad cars to ship fish eggs across the country.

Today, U.S. aquaculture is a US$1.5 billion industry and the world’s fastest-growing food sector. Much of the salmon you see in grocery stores started as farm-raised hatchlings. NOAA provides training, grants and regional data to support the industry.

Men stand in line with pails to deposit them in a train car on a siding.
Men carry pails of fish specimens to a U.S. Fish Commission ‘fish car’ – a train car designed specifically for transporting fish or fish eggs to stock U.S. rivers, lakes and coastal waters – in this historical photo.
Smithsonian Institution Archives

NOAA Fisheries also helps to regulate commercial and recreational fishing to keep fish populations healthy and prevent them from crashing.

The 1976 Magnuson-Stevens Fishery Conservation and Management Act and other laws implemented catch limits to prevent overfishing. To develop fair regulations and combat illegal practices, NOAA and its predecessors have worked with fishing organizations through regional fishery management councils for decades.

These industries generate $321 billion in sales and support 2.3 million jobs.

Restoring coral reefs to help marine life thrive

NOAA also benefits U.S. coastal communities by restoring coral reefs.

Corals build up reefs over centuries, creating “cities of the sea.” When they’re healthy, they provide nurseries that protect valuable fish species, like snapper, from predators. Reefs also attract tourism and protect coastlines by breaking up waves that cause storm-driven flooding and erosion.

The corals of Hawaii, Florida, Puerto Rico and other tropical areas provide over $3 billion a year in benefits – from sustaining marine ecosystems to recreation, including sport fishing.

However, reefs are vulnerable to pollution, acidification, heat stress and other damage. Warming water can cause coral bleaching events, as the world saw in 2023 and 2024.

NOAA monitors reef health. It also works with innovative restoration strategies, such as breeding strains of coral that resist bleaching, so reefs have a better chance of surviving as the planet warms.

Battling invasive species in the Great Lakes

A third important aspect of NOAA’s coastal work involves controlling invasive species in America’s waters, including those that have menaced the Great Lakes.

Zebra and quagga mussels, spiny water flea and dozens of other Eurasian organisms colonized the Great Lakes starting in the late 1900s after arriving in ballast water from transoceanic ships. These invaders have disrupted the Great Lakes food web and clogged cities’ water intake systems, causing at least $138 million in damage per year.

Hoses on a boat covered in zebra mussels.
Zebra mussels found attached to this boat at an inspection station in Oregon show how easily invasive species can be moved. The boat had come from Texas and was on its way to Canada.
Oregon Department of Fish & Wildlife, CC BY-SA

In the Northwest Atlantic, Caribbean and Gulf of Mexico, invasive lionfish, native to Asia and Australia, have spread, preying on native fish essential to coral reefs. Lionfish have become one of the world’s most damaging marine fish invasions.

NOAA works with the Coast Guard, U.S. Geological Survey and other organizations to prevent the spread of invasive aquatic species. Stronger ballast water regulations developed through the agency’s research have helped prevent new invasions in the Great Lakes.

Understanding climate change

One of NOAA’s most crucial roles is its leadership in global research into understanding the causes and effects of climate change.

The oil industry has known for decades that greenhouse gases released into the atmosphere from burning fossil fuels would raise global temperatures.

Evidence and research from around the world have connected greenhouse gas emissions from human activities to climate change. The data have shown how rising temperatures have increased risks for coastal areas, including worsening heat waves and ocean acidification that harm marine life; raising sea levels, which threaten coastal communities with tidal flooding and higher storm surges; and contributing to more extreme storms.

NOAA conducts U.S. climate research and coordinates international climate research efforts, as well as producing the data and analysis for weather forecasting that coastal states rely on.

Why tear apart an irreplaceable resource?

When Republican President Richard Nixon proposed consolidating several different agencies into NOAA in 1970, he told Congress that doing so would promote “better protection of life and property from natural hazards,” “better understanding of the total environment” and “exploration and development leading to the intelligent use of our marine resources.”

The Trump administration is instead discussing tearing down NOAA. The administration has been erasing mentions of climate change from government research, websites and policies – despite the rising risks to communities across the nation. The next federal budget is likely to slash NOAA’s funding.

Commercial meteorologists argue that much of NOAA’s weather data and forecasting, also crucial to coastal areas, couldn’t be duplicated by the private sector.

As NOAA marks its 55th year, I believe it’s in the nation’s and the U.S. economy’s best interest to strengthen rather than dismantle this vital agency.The Conversation

Christine Keiner, Chair, Department of Science, Technology, and Society, Rochester Institute of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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As flu cases break records this year, vaccine rates are declining, particularly for children and 65+ adults

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theconversation.com – Annette Regan, Adjunct Associate Professor of Epidemiology, University of California, Los Angeles – 2025-02-28 07:46:00

As flu cases break records this year, vaccine rates are declining, particularly for children and 65+ adults

It’s not too late to get a flu shot.
Fat Camera/E+ via Getty Images

Annette Regan, University of California, Los Angeles

In February 2025, flu rates spiked to the highest levels seen in at least 15 years, with flu outpacing COVID-19 infections and hospitalizations for the first time since the beginning of the COVID-19 pandemic. The Centers for Disease Control and Prevention has classified this flu season as having “high” severity across the U.S.

The Conversation asked epidemiologist Annette Regan to explain why this flu season is different from last year’s and what people can do to help reduce the spread.

How do flu cases and hospitalizations this year compare with previous years?

Beginning in late January and extending through February 2025, flu hospitalizations have been higher than any other week since before 2009.

Most flu cases appear to be from influenza A strains, with a split between influenza A/H3N2 and influenza A/H1N1. These are two different subtypes of the influenza A virus.

Researchers believe that historically seasons that are predominated by influenza A/H3N2 infections tend to be more severe, but infections from influenza A/H1N1 can still be very severe.

This year’s season is also peaking “late” compared with the past three flu seasons, which peaked in early or late December.

Unfortunately, there have been a number of deaths from flu too this season. Since Jan. 1, 2025, alone, over 4,000 people, including 68 children, have died from flu. While the number of deaths do not mark a record number, it shows that flu can be a serious illness, even in children.

YouTube video
Unless directed otherwise, everyone ages 6 months and older should get a flu shot.

Why are flu cases so high this year?

There are a number of factors behind any severe season, including poor community protection from low immunization rates and low natural immunity, virus characteristics, vaccine effectiveness and increased human contact via travel, office work or schools.

Unfortunately, flu vaccination rates have declined since the COVID-19 pandemic. At the end of the 2023-24 flu season, 9.2 million fewer doses were administered in pharmacies and doctors’ offices compared with an average year before the pandemic.

In addition, since 2022, fewer and fewer doses of flu vaccine have been distributed by private manufacturers. Flu vaccination rates for adults have historically been in the 30% to 60% range, much lower than the recommended 70%. Before the COVID-19 pandemic, flu vaccination rates were increasing by around 1% to 2% every year.

Flu vaccination rates began dropping after the COVID-19 pandemic, especially in higher-risk groups. Flu vaccination in children has dropped from 59% in 2019-20 to 46% in 2024-25. In adults 65 years and older, the group with the greatest risk of hospitalization and death, flu vaccination rates dropped from 52% in 2019-20 to 43% in 2024-25.

Lower vaccination rates mean a greater portion of the population is not protected by vaccines. Data shows that vaccination reduces the risk of flu hospitalization. Even if a vaccinated person gets infected, they may be less likely to experience severe illness. As a result, low vaccination rates could contribute to higher flu severity this season.

However, low vaccination rates are probably not the only reason for the high rates of flu this season. In previous severe seasons, genetic changes to the viruses have made them better at infecting people and more likely to cause severe illness.

The effectiveness of annual flu vaccines varies depending on how well the vaccine matches the circulating virus. The effectiveness of vaccines ranges from 19% to 60% in any given season. In the 2023-24 flu season, the vaccine was 42% effective.

Similarly, early 2024-25 data from the U.S. shows that the vaccine was 41% to 55% effective against flu hospitalizations in adults and 63% to 78% effective against flu hospitalizations in children.

YouTube video
Something as simple as regular handwashing could keep you from getting the flu.

How do seasonal flu symptoms differ from COVID-19 and other illnesses?

It’s important to remember that people often incorrectly refer to “the flu” when they have a common cold. Flu is caused only by the influenza virus, which tends to be more severe than common colds and more commonly causes a fever.

Many of the signs and symptoms for flu, COVID-19 and other respiratory viruses are the same and can range from mild coldlike symptoms to pneumonia and respiratory distress. Common flu symptoms are fever, cough and fatigue, and may also include shortness of breath, a sore throat, nasal congestion, muscle aches and headache.

Some symptoms, such as changes in or loss of taste and smell, are more common for COVID-19. For both COVID-19 and flu, the symptoms do not start until about one to four days after infection, and symptoms seem to last longer for COVID-19.

The only way to know what virus is causing an infection is to test. This can be done using a rapid test, some of which now test for flu and COVID-19 together, or by seeing a doctor and getting tested using a nasal swab. There are prescription antiviral medications available to treat flu and COVID-19, but they need to be taken near the time that symptoms start.

Some people are at high risk of severe flu and COVID-19, such as those who are immunosuppressed, have diabetes or have chronic heart or lung conditions. In these cases, it is important to seek early care and treatment from a health care professional. Some doctors will also prescribe via telehealth calls, which can help reduce the strain on doctors’ offices, urgent care centers and emergency rooms when infection rates are high.

What can people do now to help steer clear of the flu?

There are a number of ways people can reduce their risk of getting or spreading flu. Since the flu season is still underway, it’s not too late to get a flu vaccine. Even in seasons when the vaccine’s effectiveness is low, it is likely to offer better protection compared with remaining unvaccinated.

Handwashing and disinfecting high-traffic surfaces can help reduce contact with the flu virus. Taking efforts to avoid contact with sick people can also help, including wearing a mask when in health care facilities.

Finally, remember to take care of yourself. Exercising, eating healthy and getting sufficient sleep all help support a healthy immune system, which can help reduce chances of infection.

Those who have been diagnosed with flu or are experiencing flu-like symptoms should avoid contact with other people, especially in crowded spaces. Covering coughs and sneezes can help reduce the amount of virus that is spread.The Conversation

Annette Regan, Adjunct Associate Professor of Epidemiology, University of California, Los Angeles

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Texas records first US measles death in 10 years – a medical epidemiologist explains how to protect yourself and your community from this deadly, preventable disease

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theconversation.com – Daniel Pastula, Professor of Neurology, Medicine (Infectious Diseases), and Epidemiology, University of Colorado Anschutz Medical Campus – 2025-02-28 07:46:00

Texas records first US measles death in 10 years – a medical epidemiologist explains how to protect yourself and your community from this deadly, preventable disease

Young children are especially vulnerable to measles.
Bilanol via Getty Images

Daniel Pastula, University of Colorado Anschutz Medical Campus

On Feb. 26, 2025, Texas health officials announced the death of a child in a measles outbreak – the first measles death in the United States since 2015. The outbreak was first identified in early February in Gaines County, Texas, where just 82% of kindergartners are vaccinated against measles, compared with 93% on average across the country. As of Feb. 27, there were at least 124 confirmed cases in Texas and nearby towns in New Mexico.

In an interview with The Conversation U.S. associate health editor Alla Katsnelson, neurologist and medical epidemiologist Daniel Pastula explains why measles is so dangerous and how people and communities can protect themselves from the virus.

What is measles, and where does it come from?

Measles is an ancient disease caused by a virus that probably evolved in cattle and jumped into humans around 500 B.C. One of the first written accounts of it comes from a Persian physician named Rhazes in the ninth century C.E., and measles epidemics were described in medieval Europe and western Asia regularly beginning around 1100-1200. The virus got brought over to the Americas in the 1500s, and it wiped out large populations of native people as Europeans colonized the continent.

By the 1950s in the United States, there were 500,000 reported cases of measles each year – though the true number was probably closer to 4 million . It was so contagious, every kid was thought to have gotten measles by age 15. At that time, measles caused close to 50,000 hospitalizations annually and about 500 deaths, usually in children. It also caused over 1,000 cases of severe brain inflammation every year.

The first measles vaccine became available in 1963, and scientists improved it over the following decades, causing the number of cases to plummet. In 2000, measles was declared eliminated from the U.S.

Since then, there have been occasional minor flare-ups, usually brought in by international travelers, but by and large, measles outbreaks have been rare. No one had died of it in the United States in nearly a decade.

Today, measles infections in the U.S. are almost completely preventable with vaccination.

A vial of MMR vaccine with syringe
For most people, two doses of the MMR vaccine protects against measles for life.
Sergii Iaremenko/Science Photo Library via Getty Images

What are the typical symptoms of measles?

About 10 to 14 days after infection, people suffering from measles experience a very high fever, cold-like symptoms including a runny nose and sneezing, and eye inflammation called conjunctivitis.

Next, they may develop white spots called Koplik spots inside their mouth and a diffuse, spotty, red rash that starts at the head and neck, then descends across the entire body. This rash is where the disease gets its name – the word “measles” is thought to come from a medieval Dutch word for “little blemishes.”

Symptoms of measles infection take about three weeks to resolve. People are contagious from about four days before symptoms emerge to four days after the rash starts.

What are the possible severe outcomes of measles?

Epidemiologists estimate that 1 in 5 people who are infected with measles get sick enough to be hospitalized. About 1 in 10 develop ear infections, some of which may result in permanent deafness.

About 1 in 20 people develop severe measles pneumonia, which causes trouble breathing. Reports from west Texas this month suggest that many infected children there have measles pneumonia.

About 1 in 1,000 people develop severe brain swelling. Both measles pneumonia and brain swelling can be fatal. About 3 in 1,000 people die after contracting measles.

In about 1 in 10,000 who get sick with measles and recover from it, the virus lies dormant in the brain for about a decade. It then can reactivate, causing a severe, progressive dementia called subacute sclerosing panencephalitis, which is fatal within one to three years. There is no treatment or cure for the disease. I have seen a couple of suspected cases of subacute sclerosing panencephalitis, and none of these patients survived, despite our best efforts.

Given how contagious measles is and how severe the outcomes can be, physicians and public health experts are gravely concerned right now.

How does measles spread?

Measles is one of the most contagious infectious diseases on the planet. The virus is so infectious that if you are in a room with an infected person and you are not vaccinated and have never had measles before, you have a 90% chance of becoming infected.

The measles virus is transmitted by droplets released into the air by infected people when they cough, sneeze or simply breathe. Virus particles can survive suspended in the air or on indoor surfaces for up to two hours, so people can get infected by touching a surface carrying virus particles and then touching their face.

Who should get the measles vaccine, and how effective is it?

The vaccine for measles has historically been called the MMR vaccine because it has been bundled with vaccines for two other diseases – mumps and rubella. Most children in the U.S. receive it as a two-dose regimen, which is 97% effective against measles.

Children generally get the first dose of the vaccine at 12-15 months old and the second dose when they are 4-6 years old. Infants who haven’t reached their first birthday generally do not receive it since their immune system is not yet fully developed and they do not develop quite as robust of an immune response. In an emergency, though, babies as young as 6 to 9 months old can be vaccinated. If an infant’s mother previously received the MMR vaccine or had been infected herself as a child, her transferred antibodies probably offer some protection, but this wanes in the months after birth.

People born before 1957 are considered immune without getting the vaccine because measles was so widespread at that time that everyone was presumed to have been infected. However, certain people in this age group, such as some health care workers, may wish to discuss vaccination with their providers. And some people who had the original version of the vaccine in the 1960s may need to get revaccinated, as the original vaccine was not as effective as the later versions.

YouTube video
In recent years, vaccination rates for measles and other diseases have fallen.

Based on available evidence, the vaccine is effective for life, so people who received two doses are most likely protected.

A single dose of the vaccine is 93% effective. Most people vaccinated before 1989 got just one dose. That year, an outbreak in vaccinated children with one dose spurred public health officials to begin recommending two doses.

People with certain risk factors who received only one dose, and everyone who has never received a dose, should talk to their health care providers about getting vaccinated. Because the vaccine is a live but weakened version of the virus, those who are severely immunocompromised or are currently pregnant cannot get it.

People who are immunocompromised, which includes those who have chronic conditions such as autoimmune disorders, are undergoing certain cancer treatments or have received an organ transplant, are more susceptible to measles even if they have been vaccinated.

In the current measles epidemic in Texas, the vast majority of people falling ill are unvaccinated. Public health officials there are urging unvaccinated people in affected areas to get vaccinated.

What measures can protect communities from measles outbreaks?

Vaccination is the best way to protect individuals and communities from measles. It’s also the most effective way to curb an ongoing outbreak.

High rates of vaccination are important because of a phenomenon called herd immunity. When people who are vaccinated do not get infected, it essentially stops the spread of the virus, thereby protecting those who are most susceptible to getting sick. When herd immunity wanes, the risk of infection rises for everyone – and especially for the most vulnerable, such as young children and people who are immunocompromised.

Because measles is so contagious, estimates suggest that 95% of the population must be vaccinated to achieve herd immunity. Once vaccine coverage falls below that percentage, outbreaks are possible.

Having robust public health systems also provides protection from outbreaks and limits their spread. Public health workers can detect cases before an outbreak occurs and take preventive steps. During a measles outbreak, they provide updates and information, administer vaccines, track cases and oversee quarantine for people who have been exposed and isolation for people who are contagious.The Conversation

Daniel Pastula, Professor of Neurology, Medicine (Infectious Diseases), and Epidemiology, University of Colorado Anschutz Medical Campus

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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