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Chronic diseases such as heart disease, diabetes, and respiratory conditions continue to set significant challenges for communities worldwide not only posing a threat to the individual's health but also contributing to high mortality rates.

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Chronic diseases are the leading cause of illness, disability, and death in America.

Most chronic diseases are caused by risk factors: smoking, poor nutrition, poor physical activity, and alcohol use.

Some groups are more affected than others because of factors that limit their ability to make healthy choices.

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Chronic diseases are the leading cause of illness, disability, and death in America.

Most chronic diseases are caused by a short list of risk factors: smoking, poor nutrition, physical inactivity, and excessive alcohol use.

Some groups are more affected than others because of factors that limit their ability to make healthy choices.

Chronic diseases in America

Definition‎

Chronic diseases such as  heart disease,  cancer, and  diabetes are the leading causes of death and disability in the United States. They are also leading drivers of the nation's $4.5 trillion in annual health care costs.

Many preventable chronic diseases are caused by a short list of risk behaviors: smoking, poor nutrition, physical inactivity, and excessive alcohol use.

Risk factors

Smoking

Cigarette smoking  causes more than 480,000 deaths each year in the United States, and over 16 million Americans are living with a disease caused by smoking. Smoking causes cancer, heart disease, stroke, lung diseases, diabetes, and chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis.

Poor nutrition and physical inactivity

Poor nutrition and  physical inactivity  are significant risk factors for obesity and other chronic diseases, such as type 2 diabetes, heart disease, stroke, certain cancers, and depression.

Excessive alcohol use

Over time,  excessive alcohol use  can lead to serious problems, including alcohol use disorder and problems with learning, memory, and mental health. Chronic health conditions linked to excessive alcohol use include high blood pressure, heart disease, stroke, liver disease, and some kinds of cancer.

Who is at risk

Some groups are at higher risk of chronic diseases because of conditions where they are born, live, work, and age. These nonmedical factors, called social determinants of health, can be positive or negative. When they are negative, they limit the opportunities to make healthy choices and get good medical care.

For example, some communities lack safe spaces like parks for people to be active, or grocery stores that sell fresh fruits and vegetables. In some rural areas, it's hard to get medical care because of doctor shortages, hospital closures, or long distances to care. This makes it challenging to get preventive screenings or specialist follow-up care.

What CDC is doing

CDC's National Center for Chronic Disease Prevention and Health Promotion supports state, local, tribal, and territorial public health organizations to reduce chronic disease risk factors. Funded programs like REACH and Getting Further Faster focus on addressing the social determinants of health, so that everyone can have the same opportunity to live their healthiest life.

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The most common chronic diseases in America, risk factors, and why some groups are more affected.

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Poverty impacting the rise of Chronic Diseases

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Poverty impacting the rise of Chronic Diseases

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Poverty doesn't just mean trouble making ends meet and having few assets. According to data from the Gallup-Healthways Well-Being Index, Americans in poverty are more likely to suffer from a variety of chronic health problems, both psychological and physical.

Of the illnesses tracked in a Gallup report on the data, depression has the greatest gap between those in poverty and not in poverty. Nearly 31 percent of adults who lived below the poverty line in 2011 said they had been diagnosed with depression at some point, almost twice as high as the rate for those not in poverty - 15.8 percent. The share of adults in poverty with asthma (17.1 percent) or obesity (31.8 percent) was also roughly 6 percentage points higher in each case than the share of adults not in poverty. The study also showed that diabetes, high blood pressure, and heart attacks were slightly more likely to afflict those in poverty than those who are not.

"It was interesting to see that depression appears to disproportionately affect those in poverty more than other chronic conditions - and to see the extent of the difference," says Elizabeth Mendes, deputy managing editor at Gallup, in an email to U.S. News.

While that finding is striking, the Gallup report points out that the causal relationship between depression and poverty - not to mention the other diseases listed in the study - is complicated. Depression can be associated with other chronic illnesses, and depression can both lead to and result from poverty. In addition, outside factors could contribute to any of these problems.

One outside factor is health habits. Smoking was far more prevalent among adults in poverty, 33 percent of whom said they were smokers, compared to 19.9 percent of those not in poverty.

The differences for exercise and eating habits are much smaller. Just over half - 51.5 percent - of adults above the poverty line said that they exercise for at least 30 minutes, three or more days a week, compared to 48 percent for adults in poverty.

Meanwhile, 56 percent of adults who are not in poverty said that they eat five or more servings of fruits and vegetables, four or more days a week - nearly 6 percentage points higher than the share of adults in poverty who said they did the same. However, the share who said that they ate healthy all day "yesterday" was virtually identical for both groups - around 65 percent.

That may point to differences in perceptions about what it means to be healthy, says Mendes.

"It is interesting that we find that those in poverty are just as likely as those who aren't to say they ate healthy, but are less likely to say they ate fruits and vegetables frequently. This may point to the two groups having different frameworks for what qualifies as healthy eating," she writes.

But also contributing to lower produce consumption among the poor may simply be lower availability. Only 83.7 percent of those in poverty said it was "easy to get affordable fresh fruits and vegetables," compared to 91.7 percent of those not in poverty.

It's also important to remember, when looking at any data about poverty, that while poverty is a binary measure, income is not. That is, a person just barely above the poverty line and a person just barely below it likely have similar living situations, despite being classified in two different groups. All of which means that these data only begin to describe the health differences between people at varying points on the income distribution.

Danielle Kurtzleben is a business and economics reporter for U.S. News & World Report. Connect with her on Twitter @titonka or via E-mail at dkurtzleben@usnews.com.

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Americans in Poverty at Greater Risk for Chronic Health Problems

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A new report from Gallup shows the relationship between illness, healthy habits, and economic status.

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Preventive medicine plays a crucial role in managing chronic diseases by focusing on early detection, lifestyle modifications, and proactive health management.

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The benefits of exercise confirm that exercise improves health and can extend your life.

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The secret to better health - exercise - Harvard Health

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This article is part of a series of explainers on vaccine development and distribution. Learn more about vaccines - from how they work and how they're made to ensuring safety and equitable access - in WHO's Vaccines Explained series.

COVID-19 vaccines have proven to be safe, effective and life-saving. Like all vaccines, they do not fully protect everyone who is vaccinated, and we do not yet know how well they can prevent people from transmitting the virus to others. So as well as getting vaccinated, we must also continue with other measures to fight the pandemic.

Vaccine efficacy and effectiveness

All COVID-19 vaccines by WHO for approved emergency use listing have been through randomized clinical trials to test their quality, safety and efficacy. To be approved, vaccines are required to have a high efficacy rate of 50% or above. After approval, they continue to be monitoredfor ongoing safety and effectiveness. But what is the difference between efficacy and effectiveness?

A vaccine's efficacy is measured in a controlled clinical trial and is based on how many people who got vaccinated developed the 'outcome of interest' (usually disease) compared with how many people who got the placebo (dummy vaccine) developed the same outcome. Once the study is complete, the numbers of sick people in each group are compared, in order to calculate the relative risk of getting sick depending on whether or not the subjects received the vaccine. From this we get the efficacy - a measure of how much the vaccine lowered the risk of getting sick. If a vaccine has high efficacy, a lot fewer people in the group who received the vaccine got sick than the people in the group who received the placebo.

So, for example, let's imagine a vaccine with a proven efficacy of 80%. This means that - out of the people in the clinical trial - those who received the vaccine were at a 80% lower risk of developing disease than the group who received the placebo. This is calculated by comparing the number of cases of disease in the vaccinated group versus the placebo group. An efficacy of 80% does not mean that 20% of the vaccinated group will become ill.

Vaccine effectiveness is a measure of how well vaccines work in the real world. Clinical trials include a wide range of people - a broad age range, both sexes, different ethnicities and those with known medical conditions - but they cannot be a perfect representation of the whole population. The efficacy seen in clinical trials applies to specific outcomes in a clinical trial . Effectiveness is measured by observing how well the vaccines work to protect communities as a whole. Effectiveness in the real world can differ from the efficacy measured in a trial, because we can't predict exactly how effective vaccination will be for a much bigger and more variable population getting vaccinated in more real life conditions.

Vaccine protection and timing

Vaccines offer strong protection, but that protection takes time to build. People must take all the required doses of a vaccine to build full immunity. For two-dose vaccines, vaccines only give partial protection after the first dose, and the second dose increases that protection. It takes time before protection reaches its maximum level a few weeks after the second dose. For a one-dose vaccine, people will have built maximum immunity against COVID-19 a few weeks after getting vaccinated.

Vaccine protection and infection

Vaccines can stop most people from getting sick with COVID-19, but not everyone.

Even after someone takes all of the recommended doses and waits a few weeks for immunity to build up, there is still a chance that they can get infected. Vaccines do not provide full (100%) protection, so 'breakthrough infections' - where people get the virus, despite having been fully vaccinated - will occur.

If vaccinated people do get sick, they are likely to have milder symptoms, in general 'It is very rare for someone vaccinated to experience severe illness or die.

Vaccine protection and transmission

COVID-19 vaccines are crucial tools in the pandemic response and protect against severe disease and death. Vaccines provide at least some protection from infection and transmission, but not as much as the protection they provide against serious illness and death. More evidence is needed to determine exactly how well they stop infection and transmission.

After being vaccinated, individuals should continue taking simple precautions, such as physical distancing, wearing a mask, keeping rooms well ventilated, avoiding crowds, cleaning hands, and coughing into a bent elbow or tissue. Get tested if you are sick, even if you've been vaccinated. Check local advice where you live and work. Do it all!

Vaccine protection and variants

When cases increase and transmission accelerates, it's more likely that new dangerous and more transmissible variants emerge, which can spread more easily or cause more severe illness.

Based on what we know so far, vaccines are proving effective against existing variants, especially at preventing severe disease, hospitalization and death. However, some variants are having a slight impact on the ability of vaccines to guard against mild disease and infection.

Vaccines are likely staying effective against variants because of the broad immune response they cause, which means that virus changes or mutations are unlikely to make vaccines completely ineffective.

WHO continues to constantly review the evidence and will update its guidance as we find out more. For the latest updates on what we know about the COVID-19 variants, read our latest weekly epidemiological updates and our explainer on ' the effects of virus variants on COVID-19 vaccines '.

One of the best ways of guarding against new variants is to continue applying tried-and-tested public health measures and rolling out vaccines. All COVID-19 vaccines approved for emergency use listing by WHO have been thoroughly tested and proven to provide a high degree of protection against serious illness and death. As stronger virus variants emerge, it's important to take your vaccine when it's your turn.

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Vaccine efficacy, effectiveness and protection

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This article is part of a series of explainers on vaccine development and distribution. Learn more about vaccines - from how they work and how they're made to ensuring safety and equitable access - in WHO's Vaccines Explained series. COVID-19 vaccines have proven to be safe, effective and life-saving.

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Managing a chronic illness can be overwhelming and challenging, it’s always best to try to avoid developing a disease by practicing preventative measures, however, if a disease does arise there are successful ways that can reverse or maintain the symptoms.