Childhood Immunization

Diphtheria use to be a major cause of childhood illness and death. Through the 1920's about 150,000 people got diphtheria each year in the U.S. and about 10% of them died. “The word diphtheria struck fear into the hearts of parents in those days, but today there are only a few cases a year. This change is due largely to our parents and grandparents, who got their children immunized.” ¹

Diphtheria is a disease caused by bacteria called Corynebacterium diphtheriae. These bacteria live in the mouth, throat and nose of an infected person, and are easily spread to others through coughing or sneezing. Some people with diphtheria might not even seem ill, but they can still spread the disease.

Two to four days after a child is exposed to diphtheria, he might get a sore throat, a slight fever, and chills. If diphtheria is not properly diagnosed and treated, it can then produce a powerful toxin, which spreads throughout the body. Serious complications are heart failure or paralysis. Sometimes a thick membrane forms in a child’s throat, making it hard to swallow or even breathe. The mortality is about 10%. A child with diphtheria is contagious for about 2 to 4 weeks.

Diphtheria vaccine protects children by creating immunity to the toxin that causes symptoms of illness, rather than immunity to the bacteria itself. Because it acts on the toxin, it is called a toxoid.

Diphtheria toxoid is almost always given to children together with tetanus toxoid and pertussis vaccine in a combined vaccination shot known as DTaP. Diphtheria toxoid was developed around 1921. In 1921 there were 206,939 cases reported; in 1931 there were 70,839 cases; in 1941 there were 17,987; in 1951 there were 3,983; and in 1961 there were 617 cases. Today there are only a few cases a year. ¹

Tetanus enters the body through cuts in the skin. It can get in through even a tiny pinprick or scratch, but it prefers deep puncture wounds or cuts, like those made by nails or knives. Tetanus can be transmitted following severe burns, ear infections, tooth infections, or animal bites. Rusty nails are often blamed for causing tetanus, but it is the tetanus bacteria, and not rust, that causes the disease. You can get tetanus from a shiny nail as easily as from a rusty one. Tetanus is not contagious. People get it only from the environment and not from other people.

Tetanus bacteria can live anywhere, but they are usually found in soil, dust, and manure. Once they get into the body through a wound, it can take from 3 days to 3 weeks (usually about 8 days) for the first symptoms to appear. These are usually a headache, crankiness, and spasms of the jaw muscles.

Tetanus produces a toxin inside the body. As this toxin spreads, it causes muscle spasms in the neck, arms, legs, and stomach. It can cause painful muscle contractions strong enough to break a child’s bones. Children with tetanus might have to spend several weeks in the hospital under intensive care. There are only about 50 cases of tetanus a year in the U.S. It has a 30% mortality rate.

As with the diphtheria vaccine, tetanus vaccine is really a toxoid, which protects against the toxin produced by tetanus bacteria. Tetanus toxoid is almost always given to children in DTaP vaccine, along with diphtheria and pertussis. Tetanus toxoid was first produced in 1924. In the 1940’s about 400-500 tetanus cases were reported each year. By the mid-1970's this had dropped to 50-100 cases, and by the 1990's to between 40 and 50. ¹

Pertussis causes a child to cough violently and rapidly, over and over, until the air is gone from his lungs. The child is then forced to inhale with the loud whooping sound that gives the disease its nickname, Whooping Cough. Then the coughing begins again. These severe coughing spells can go on for weeks. The child becomes cyanotic or vomits after a coughing spell. A child with Whooping Cough can have difficulty eating, drinking, or even breathing.

Pertussis is a very contagious disease, and one that is fairly common. It is caused by bacteria called Bordetella pertussis that live in the mouth, nose, and throat. Pertussis is spread by personal contact, coughing and sneezing.

It usually takes a week to 10 days from the time a child is exposed until symptoms appear. At first, pertussis looks like a common cold. The initial symptoms are sneezing, runny nose, fever and a mild cough. But after 1 or 2 weeks the severe coughing spells begin. This stage of the disease usually lasts 1 to 6 weeks, but can last longer. After the coughing stage has passed the child usually recovers gradually over 2 to 3 weeks. A child with pertussis can give the disease to another child from about a week after exposure till about 3 weeks after the severe coughing starts.

Pertussis is most severe in infants under 1 year old. More than half of these infants who get the disease must be hospitalized. Older children and adults can get pertussis too, but it is much less severe and might not even be recognized as pertussis. Many infants who get pertussis catch it from their older brothers and sisters or from their parents.

Pertussis can cause serious complications. About 10% of children with pertussis also get pneumonia, and about 2% will have convulsions. 0.4% of people who get pertussis develop encephalopathy. Pertussis causes about 10-15 deaths a year in the U.S.

The first pertussis vaccine was developed in the 1930's. In the early 1990's a new cellular pertussis vaccine became available. It works as well as the older vaccine but has fewer side effects. Pertussis vaccine is almost always given in DTaP vaccine, along with diphtheria and tetanus toxoids. The series of pertussis vaccinations give immunity until the age of 10.  Pertussis vaccine is not licensed for older children, so we cannot give booster doses to keep protection from fading. However, pertussis vaccine for older children and adults might be available in the near future.

The number of pertussis cases reported to CDC has dropped by more than 98%. There were over 183,000 cases reported in 1940, about 120,000 cases in 1950, fewer than 15,000 cases in 1960, and fewer than 5,000 cases most years since 1970. ¹

Polio was one of the most dreaded childhood diseases of the 20th Century in the U.S. An epidemic in 1916 killed 6,000 people and left 27,000 more paralyzed. Since polio vaccine became available in 1955 the disease has disappeared from the U.S., and may soon be gone from the rest of the world as well. The number of cases of paralytic polio in the U.S. has fallen from more than 20,000 in 1952 to only a few cases a year today. ¹ The few cases that have occurred in recent years have not been caused by the natural disease, but by one type of polio vaccine.

But even though there is no polio in the U.S. or in fact in the Western hemisphere it is still common in some parts of the world. A single infection brought into the country by someone traveling from one of these regions could lead to polio epidemics all over again if we were not protected. That is why we continue to vaccinate. Polio is caused by a virus that lives in the throat and intestinal tract. It is spread through contact with the bowel movements of an infected person (for instance, by changing diapers).

Some children who get polio don’t feel ill at all. For others, polio simply feels like a cold, with symptoms appearing about 6-20 days after exposure. Sometimes these children will also feel some pain and stiffness in their neck, back, and legs, but this soon goes away.

However, some children who get polio become paralyzed. This is called paralytic polio. Paralytic polio can start like a common cold, but often with severe muscle pain. Paralysis usually comes within the first week. Most often it affects the child’s legs, but sometimes it affects other muscles including those that control breathing. Some children recover from their paralysis, but many will be permanently disabled.

There is no treatment for polio, and some children die from it. Polio is most contagious from about 7-10 days before symptoms appear till about 7-10 days afterward.

There are two types of polio vaccine: Inactivated (killed) polio vaccine (IPV), which is a shot; and live oral polio vaccine (OPV), which is a liquid that is swallowed. CDC recommends only IPV, except in very limited circumstances. Children should get 4 doses of IPV at these ages:

• A dose at 2 months of age
• A dose at 4 months of age
• A dose at 6-18 months of age
• A booster dose at 4-6 years of age

OPV is an excellent vaccine. “Without it we could not have eliminated polio from the western hemisphere, and would not be so close to eliminating it from the rest of the world.” 1 Until recently, OPV was recommended for most children in the U.S. But OPV can also, in some situations, actually cause polio. This is rare about once in every 2.4 million doses.

When the vaccine was preventing thousands of cases of polio a year, having it occasionally cause a case was a small price to pay. But now that the risk of getting polio is extremely low, and because IPV is available, experts have decided that routinely using the oral vaccine in the U.S. is no longer worth the small risk. OPV is still used in parts of the world where the risk of polio disease is much higher. Four doses of polio vaccine will protect most children for life.  However for certain people, for instance, those traveling to countries where polio is still common, a booster dose is recommended.

Not everyone recognizes measles as the serious disease it really is, possibly because it used to be a routine part of everyone’s childhood and also because we don’t see it nearly as much as we used to. But measles can be deadly. Measles still kills about a million people a year around the world. Measles can also make a pregnant woman have a miscarriage or give birth prematurely.

For most children, measles means a rash and a cold, and missing a few days of school. But about 10% children who get measles also get an ear infection. And up to 5% of them get pneumonia. About 0.1% will get encephalitis. Out of every 1,000 children who get measles, 1 or 2 die from it. ¹

Measles is caused by a virus. It spreads so easily that any child who is exposed to it and is not immune will probably get it. You can get measles from an infected person who coughs or sneezes around you or even talks to you. Before measles vaccine was available, nearly all children got measles by the time they were 15 years old. Around 500,000 cases a year were reported in the U.S. during the 10 years before measles vaccine, and there were probably another 3 million cases a year that were not reported. During each of these years more than 450 people died because of measles, 48,000 were hospitalized, 7,000 had seizures, and about 1,000 suffered permanent brain damage or deafness. ¹

The first signs of measles are a fever, runny nose, and cough, which appear about 10-12 days after a child is exposed. The rash appears several days later. A child with measles is contagious from about 4 days before the rash appears to about 4 days after.

Measles vaccine became available in 1963. As children started getting the vaccine, measles quickly began to disappear. Today we see only about a hundred cases a year. But even though the number of measles cases each year is only a fraction of what it used to be, this doesn’t mean that our children cannot get measles.

In 1989 and 1990 we saw a large jump in measles cases and deaths, partly because many parents weren’t getting their preschool-aged children vaccinated. In response to this outbreak, doctors and health departments stepped up their efforts to vaccinate children, and measles cases have since dropped to all-time low levels.

The measles vaccine used today is a live, attenuated vaccine. In other words, the virus that is used to make the vaccine is not killed, but it is weakened so that doesn’t cause measles. Measles vaccine can be given by itself, but it is usually given together with mumps and rubella vaccines in a shot called MMR.

Before vaccines, mumps was a common childhood disease. The most obvious sign of mumps is swelling of the cheeks and jaw, which is caused by inflammation in the salivary glands. Children with mumps usually also get a fever and headache. Generally, Mumps is a mild disease, but it does have its serious side:

• About 10% of those who get mumps also get meningitis.

• Occasionally mumps also causes encephalitis, which is inflammation of the brain itself. Usually the child recovers without permanent damage.

• About 25% of teenage or adult men who get mumps develop a painful swelling of the testicles.

• Mumps can, rarely, cause deafness (about 1 in 20,000 cases) or death (about 1 in 10,000 cases).

Children get mumps through contact with others who are already infected with the mumps virus. The virus is spread through the air by coughing, sneezing, or simply talking. Children start to show signs of mumps 2 to 3 weeks after they are exposed. They are contagious from about 12 to 24 days after exposure.

The mumps vaccine we use today was licensed in 1967, and is a live, attenuated (weakened) vaccine. The number of reported cases has dropped from over 150,000 in 1968 to only 666 in 1998. ¹ Mumps vaccine is usually given together with measles and rubella vaccines in a shot called MMR.

When children get rubella, it is usually a mild disease, with a slight fever that lasts for about 24 hours, and a rash on the face and neck that lasts two or three days. Rubella is also called German measles or 3-day measles. It is caused by the rubella virus, and usually strikes in the winter and spring. It is spread through close contact such as coughing, sneezing, or talking. Most children recover quickly and completely.

Rubella also strikes adults, and outbreaks can occur among teenagers and adults who have not been immunized. Adults who get rubella may get swollen glands in the back of the neck and pain, swelling, or stiffness in their joints (arthritis).

But the greatest danger from rubella is not to children or adults, but to unborn babies. If a woman gets rubella in the early months of her pregnancy, there is an 80% chance that her baby will be born with birth defects. This is called Congenital Rubella Syndrome (CRS). Babies with CRS may be born deaf or blind. They may have damaged hearts or small brains. Many are mentally retarded. Miscarriages are also common among women who get rubella while they are pregnant.

It takes about 12-23 days from the time of exposure for people to start showing signs of the disease. Rubella is most contagious while the rash is visible, but it can be spread from about a week before the rash starts until about a week after. Rubella Fact: The last major rubella epidemic in the U.S. was in 1964-65. An estimated 12½ million people got the disease, including 20,000 babies born with congenital rubella syndrome. This epidemic cost the country an estimated $1.5 billion.

Rubella vaccine was first licensed in the U.S. in 1969, and the vaccine we use today was licensed in 1979. It is a live, attenuated (weakened) vaccine. There are now only several hundred cases reported each year, with the record low (128 cases) reported in 1995.  Rubella vaccine can be given by itself, but it is usually given together with measles and mumps vaccines in a shot called MMR.

Most children get Measles, Mumps and Rubella vaccines all together in one shot called MMR. All three of these vaccines work very well, and will protect most children for the rest of their life.

Children should get two doses of MMR vaccine. The first is given between 12 and 15 months of age. The second may be given at any time, as long as it is at least 28 days after the first. It is usually given at 4-6 years of age, before the child enters kindergarten or first grade.

Measles, mumps, and rubella vaccines can be given separately, too. But this is not usually done because it means giving a child three shots instead of one. Sometimes, usually during a measles outbreak, children might be given measles or MMR vaccine before their first birthday. This is for short-term protection only. These children should still be given two doses of MMR vaccine at the usual ages.

Haemophilus influenzae type b or Hib disease is a childhood disease that is not as well known, but is just as dangerous as other previously mentioned childhood diseases. Even though the word influenza is part of its name, Hib is not related to influenza (flu).

As recently as the mid-1980's, Hib disease struck 0.5% of children under 5 years old in the U.S. Every year about 12,000 children got meningitis as a result of Hib. In fact, Hib disease was the leading cause of bacterial meningitis in children under five. About 25% of these children suffered permanent brain damage, and about 5% died. In addition, about 8,000 children a year suffered from other serious complications, such as pneumonia. ¹

Hib is a bacterial disease. It is spread through the air by coughing, sneezing, or even breathing. Hib bacteria enter a child’ system through the nose or throat, and if they stay in the nose and throat the child will probably not become sick. But sometimes the bacteria spread into the lungs or bloodstream. This is called invasive Hib disease, and it can cause serious complications. In addition to meningitis, invasive Hib disease can lead to: pneumonia, epiglottitis, arthritis, and other problems.

Most invasive Hib disease occurs in children under 5 years old, and up to 60% in children younger than 1 year. The disease is not common in older children or adults. Most Hib disease today strikes infants who are not immunized. It probably takes about 2-4 days from the time a child is exposed to Hib bacteria until symptoms appear. An infected person can spread the disease to others for as long as the bacteria remain in the body. Antibiotics can stop the spread within 2-4 days.

Hib vaccine has had a dramatic impact on Haemophilus influenzae type B. As soon as the first vaccine came into use in 1985 the disease began to disappear. Several improved vaccines have been licensed since then, and the age for the first shot has been lowered from 24 months to 2 months. There were an estimated 20,000 cases of Hib disease a year in the mid-1980's, but now there are only a few hundred cases a year. ¹ Hib vaccine is an inactivated (killed) vaccine. It is made from only a part of the Hib bacteria.

Several different companies make Hib vaccine. Children should get either 3 or 4 doses, depending on which company’s vaccine your doctor or clinic is using. All children should get the vaccine at 2 and 4 months of age, and a booster dose between 12 and 15 months. Some children should get an additional dose at 6 months. Children who have passed their 5th birthday do not need Hib vaccination.

Hib vaccine can be combined (that is, given in the same shot) with DTaP vaccine, or with hepatitis B vaccine. Your doctor or nurse might offer the vaccines in these combination forms. They work just as well, and are just as safe, as if the vaccines were given separately.

The Streptococcus pneumoniae bacteria kills more people in the U.S. each year than all other vaccine-preventable diseases combined. It is commonly thought of as a disease of the elderly, but it also takes its toll among our children. Each year the pneumococcal bacteria cause invasive disease (mostly blood infection, or bacteremia) in about 16,500 children under 5 years old, including more than 700 cases of meningitis. It is the leading cause of bacterial meningitis in the country, hitting children under one year old the hardest. About 200 children die from invasive pneumococcal disease each year.

In addition, pneumococcal disease causes 25% - 40% of all middle ear infections in children. Middle ear infections are responsible for more visits to a pediatrician than any other complaint, and they are the number one reason for prescribing antibiotics to children. All children are susceptible to pneumococcal disease, but some groups have higher rates of the disease, including African Americans, American Indians, Alaska Natives, and children with certain medical conditions such as sickle cell disease or HIV infection, or who don’t have a functioning spleen.

The pneumococcal bacteria are spread from person to person, mainly through the air. The disease can be spread by anyone who is infected, even if they don’t have symptoms. Pneumococcal infections are more common during the winter and early spring.

Treating pneumococcal infections with penicillin and other antibiotics used to be effective, but the disease is becoming more and more resistant to antibiotic treatment, making immunization increasingly important.

Pneumococcal conjugate vaccine is the second part of our one-two punch against bacterial meningitis (Hib vaccine is the first). Until very recently, pneumococcal vaccine was recommended mostly for adults over 65 years old, and was not licensed at all for children under 2. This is because the only type of vaccine that was available (pneumococcal polysaccharidel vaccine) doesn’t work very well for young children. Now a different type of vaccine (pneumococcal conjugate vaccine) has been licensed that works for children under 2, and it is finally possible to prevent pneumococcal disease in that vulnerable age group.

Pneumococcal conjugate vaccine is an inactivated (killed) vaccine. It gives immunity against the 7 strains of the pneumococcal bacterium that cause most of the serious infections in children. This vaccine should prevent most meningitis and bacteremia caused by pneumococcal bacteria. However, there are other causes of bacteremia and meningitis, and this vaccine will not prevent them. It will also not prevent all ear infections. Some ear infections are caused by pneumococcal disease, but many are caused by other germs too, and the vaccine will not prevent these.

Children should routinely get 4 doses of the vaccine, one dose each at 2, 4, 6, and 12-15 months of age. Children who begin the series later may not need as many doses. Children over 5 years old will generally not get the pneumococcal conjugate vaccine. Older children who need protection from pneumococcal disease (those with certain chronic diseases or damaged immune systems) can get the polysaccharide vaccine, or may get a series that includes both vaccines. Your doctor or clinic staff will tell you if our older children need protection from pneumococcal disease. Pneumococcal vaccine may be given at the same time as other childhood vaccines.

Hepatitis B is a disease that affects the liver. It is one of several hepatitis diseases (for example, hepatitis A and hepatitis C). These are caused by different germs, but are similar in that they all affect the liver (hepatitis comes from the Greek words for liver and inflammation). Hepatitis B is caused by a virus. Some people who are infected with the hepatitis B virus never feel sick. Others have symptoms that might last for several weeks. Those symptoms can include: loss of appetite and tiredness, pains in muscles, joints or stomach, diarrhea, vomiting or jaundice. This is called acute hepatitis B.

Some people never recover from hepatitis B. They develop what is called chronic hepatitis B virus infection. They might not look or feel sick, but they will probably carry the hepatitis B virus in their blood for the rest of their lives, and they can infect other people. Many of these chronically infected people will suffer from serious health problems, such as cirrhosis or liver cancer. In fact, the hepatitis B virus causes most of the liver cancer in the world. In the U.S. alone, there are more than 1 million people chronically infected with the hepatitis B virus. In 1996, an estimated 200,000 people became infected with hepatitis B virus, and about 4,000 to 5,000 people a year die from hepatitis B. ¹

Hepatitis B virus is spread through contact with the blood, or other body fluids, of an infected person. People can get hepatitis B by having unprotected sex, by sharing drug needles, or by sharing personal items like razors or toothbrushes with someone who is infected. Doctors, nurses, and other health care workers can get hepatitis B through exposure to blood from infected patients. Police, fire fighters, and paramedics who are exposed to blood are also at risk.

Why, then, do we immunize children against hepatitis B when they don't have sex, don’t take drugs, and are not nurses or police officers? One important reason is that babies can get infected too. If a mother is chronically infected with hepatitis B, her baby could become infected during birth. If these babies are not immunized immediately, most of them will become chronically infected too. One out of 4 of these babies will eventually die from cirrhosis or liver cancer.

Also, children can be infected through exposure to blood, saliva, or other fluids from infected children or adults. While this is not common, vaccination is a reasonable precaution, particularly since the vaccine is a very safe one. Hepatitis B is a major cause of liver cancer, and hepatitis B vaccine can prevent the disease. Therefore, hepatitis B vaccine is the first vaccine that prevents cancer.

You can protect children from hepatitis B by getting them vaccinated with three doses of hepatitis B vaccine. Newborn babies whose mothers either are infected with the hepatitis B virus or have not been tested should get their first shot within 12 hours of birth, the second shot at 1-2 months of age, and the third shot at 6 months of age. Other babies can get their first shot between birth and 2 months of age, the second at 1-4 months of age, and the third at 6-18 months of age. ¹

Babies born to infected mothers should also get Hepatitis B Immune Globulin (HBIG) within 12 hours of birth. These babies should also be checked when they are 9-15 months old to make sure the vaccine worked and that they do not have chronic hepatitis B virus infection.

The second shot should always be given at least one month after the first shot, and the third shot at least 2 months after the second and 4 months after the first. If you miss a dose or get behind schedule, there is no need to start over. Just get the next dose as soon as possible and continue on schedule. After the third shot, most children will be protected. They do not need booster shots.

Varicella or chickenpox is one of the most common childhood diseases. It is caused by the varicella-zoster virus. Most people in the U.S. get chickenpox while they are still children. Until the late 1990's there were about 4 million cases a year. But now that people are using varicella vaccine, that number has begun to drop. The most recognizable feature of chickenpox is an itchy rash all over the body. Children with chickenpox can also be drowsy and have a fever. The reason varicella is called chickenpox has nothing to do with chickens. Chickenpox got its nickname because the blisters look like chickpeas.

Chickenpox can be spread very easily from person to person. It is spread through the air, by coughing or sneezing, or even talking. It can also be spread by contact with fluid from the blisters. It usually takes 2-3 weeks from the time a child is exposed to chickenpox virus until he or she becomes ill. The disease is contagious from 1 or 2 days before the rash appears until all the blisters are dried up, which usually takes 4 to 5 days.

Chickenpox is usually a mild disease, uncomfortable but not dangerous. Still, serious problems do occur. The blisters can become infected, and some children get encephalitis. Of every 100,000 infants under one year old who get chickenpox, about 4 die. For older children, 1 to 14 years old, about 1 in 100,000 dies. ¹

If a woman gets chickenpox just before or after giving birth, her baby can get very sick, and about 33% of these children die if they are not treated quickly. Even when chickenpox is not serious, it can create problems for the family because the parents may have to miss work to care for the sick child. About 1 child out of 500 who get chickenpox must be hospitalized. For adults who get chickenpox, 1 in 50 must be hospitalized. ¹ After a person has chickenpox, the virus stays in the body. Years later, it can cause a painful disease called zoster, or shingles.

Varicella vaccine is a live-virus vaccine. It has been used in some parts of the world, such as Japan, for over 20 years. It was licensed in the U.S. in 1995. A single dose of varicella vaccine is recommended for children between 12 and 18 months of age. It is usually given at the same time as the MMR shot. Children who miss this shot can still get a single dose of the vaccine up to their 13^th birthday. Adolescents or adults who haven’t gotten the vaccine by their 13^th birthday will need two doses, 4 to 8 weeks apart. A child who has already had chickenpox disease does not need to get the shot.

It appears that the vaccine prevents chickenpox in about 70% to 90% of people who get the shot, and prevents severe chickenpox in over 95%. The vaccine used in Japan is still protecting those people who were vaccinated 20 years ago. In the U.S., people who were vaccinated during testing, before the vaccine was licensed, are still immune to chickenpox. The vaccine is expected to give life-long immunity. Occasionally even children who respond to the vaccine get a very mild case of chickenpox (about 1-2 children out of a hundred).

There is some concern that a child who gets chickenpox vaccine can actually give chickenpox to other, unprotected, family members. This appears to happen extremely rarely, and only when the child who was vaccinated develops a rash. To be safe, anyone with a suppressed immune system should consider avoiding contact with a child who develops a rash after getting the chickenpox vaccination just as they should avoid anyone who has a case of chickenpox.

Hepatitis A, like other types of hepatitis, is a disease that affects the liver. It is the most common type of hepatitis reported in the U.S., with an estimated 125,000 - 200,000 cases each year. About 3 cases out of 10 occur in children under 15 years old. ¹

Hepatitis A is caused by a virus. Children under 6 years old who get infected often don’t show any signs of illness. But for most older children, signs of hepatitis can come on quickly. They include: fever, loss of appetite and tiredness, stomach pain, vomiting, dark urine or jaundice. Hepatitis A cannot be distinguished from other types of hepatitis except by blood testing.

Hepatitis A does not cause long-term illness or liver damage like hepatitis B does. But every year about 100 people die from liver failure caused by severe hepatitis A.

Hepatitis A virus is found mainly in bowel movements, and is spread through personal contact or by eating contaminated food or drinking contaminated water. For almost half the cases in the U.S. the source of the infection is not known. An infected person can spread the virus to other people from about a week before symptoms appear through about a week after. People without symptoms can still spread the disease. Even though the diseases are quite different, the hepatitis A virus is closely related to the polio virus.

Hepatitis A vaccine is an inactivated (killed) vaccine. It can be given to children 2 years old or older. Two doses are needed, the second dose given 6-18 months after the first. Hepatitis A vaccine is recommended for children in certain states: Alaska, Arizona, California, Idaho, Nevada, New Mexico, Oklahoma, Oregon, South Dakota, Utah, and Washington. It may also be considered for children in Arkansas, Colorado, Missouri, Montana, Texas and Wyoming. The vaccine is also recommended for communities with high levels of hepatitis A, including Alaska native villages, American Indian reservations, some Hispanic communities and some religious communities. It is also recommended for others who are at high risk, including people traveling to countries where the disease is common.

The following is the vaccination schedule recommended by the Center for Disease Control (CDC). If you click on the yellow highlighted words in blue font, in this section, it will open the Internet to a CDC web page with more information on that subject.

1. Centers for Disease Control, (August 2, 2001).Parents Guide to Childhood Immunization, National Immunization Publication, Retrieved 10/25/03 from http://www.cdc.gov/nip/publications/Parents-Guide/default.htm.