Simply put, vaccines have been designed and created to help reduce significant morbidity and mortality associated with a number of illnesses and diseases. To best put this in perspective, we'd like to share with you some of the specifics surrounding these vaccine-preventable diseases.
Diphtheria, Tetanus and Pertussis (DTaP): Diphtheria manifests as a membranous coat in the tonsillar and pharynx region. Although a mild form of the disease may appear as a simple upper respiratory like infection (cold) accompanied by fever, more severe complications include obstruction of the airway, paralysis, cardiac complications, and even death with a 5-10% case mortality rate. In the U.S., actual cases have dramatically decreased, but worldwide, outbreaks continue to occur, particularly in the former Soviet Union. Tetanus, yes, the disease we think about when we cut ourselves on a chain-linked fence, can appear in a generalized form: with severe muscular spasms and even a locking of the jaw with a case mortality rate of 10%, a localized form: spasms around the site of infection, and a cephalic form: where cranial nerve involvement occurs following wounds to the head and neck. Specifically, it is a neurotoxin produced by the Clostridium tetani that causes the disease. The very contagious pertussis (AKA whooping cough) may appear as a simple cold but in infants, can cause apnea, seizures, and death. Based on data from in the 1990s, the case mortality rate is 1% for children less than 2 months of age and <0.5% in infants 2 months to 1 year…which serves as a good reminder for adults to get their booster as earlier in this decade we were finding adults (fully immunized as children) were acquiring the disease secondary to waning immunity and then infecting infants not completely immunized. And for those interested in what the “a” represents in the DTaP…it stands for acellular. It was designed secondary to some concerning adverse reactions to the original DTP vaccine.
Polio: Spread via person-to-person contact via infected stools or oral/nasal secretions, polio was so very prevalent before the first vaccine was produced over 50 years ago (please see my Immunization I discussion for a bit more on the polio vaccine history). Although many infected persons never have any visible symptoms, approximately 1% develop paralysis often leading to permanent disability and occasional death. These days, there are two vaccines available, one being an oral form and the other being an inactivated form which is injected (and the one used in the U.S.).
Haemophilus influenzae b (Hib): Infections caused by Hib include meningitis, pneumonia, and epiglottitis (a very very bad throat illness). This vaccine has been remarkable in preventing the just-mentioned infections (where invasive disease has been decreased by 99%).
Hepatitis B: This disease attacks the liver and besides leading to lifelong infection, it can cause cirrhosis or scarring of the liver, liver cancer, liver failure, and death. In infants, the primary concern is perinatal transmission…not so much from in utero exposure (pregnant mom to developing fetus), but during the time of delivery. This is why pregnant women are tested for Hepatitis B status during pregnancy.
Pneumococcal Infections: The vaccine (the13 serotype form…i.e., covering for 13 different types of the Streptococcus pneumoniae bacteria) is used to prevent a variety of childhood illnesses ranging from ear infections to sinus infections to serious pneumonias to meningitis. Since 2000, when this vaccine was first used, all invasive disease caused by this bacteria has decreased by 80% for children less than 2 years of age.
Rotavirus: Although a different vaccine existed a few years back for prevention of rotavirus…which happens to be the leading cause of gastroenteritis (AKA “stomach bugs”) among children worldwide, the two oral vaccines that currently exist are the newest on the block as far as what is available during the first year. In the 2-3 years since we’ve been using this vaccine, there has been a tremendous reduction in the number of cases here in the U.S., and therefore, emergency room visits and hospitalizations. And, to date, no increased incidence of intussusception (a concern of the vaccine from a few years ago)…where a blockage of the intestine occurs following the “telescoping” of one part of the small intestine into another part.
Varicella (AKA chicken pox): Many of us had the chicken pox…those 400-500 lesions scattered all over our bodies. The lesions tend to be very itchy and often accompany symptoms of fever, fatigue, and that overall sense of just feeling crummy. Prior to the vaccine, spread from person to person didn’t require too much…just being in the same room is all that it took. Spread can also occur from direct contact with the lesions and the incubation period (from time of exposure to disease symptoms) is about 2-3 weeks. Unfortunately, one is contagious in the 24-48 hours prior to any lesions appearing and lasts until they all have scabbed over. Prior to the vaccine, 1 out of 500 children with chicken pox required hospitalization (with some of these children developing encephalitis) and of 100,000 infants who acquired the illness, about 4 would die. Furthermore, if a pregnant woman acquires the infection during the latter stages of pregnancy (just prior to giving birth or just after delivering), a great percentage of these newborns die. Since the vaccine was introduced in the mid-1990s, the above numbers and concerns have certainly subsided.
Hepatitis A: Although quite often a self-limited illness, symptoms usually include poor appetite, jaundice, fever and again, that overall sense of feeling crummy, but it should be noted in children less than 6 years of age, only 30% will be symptomatic. Acute liver failure is rare with a case-fatality rate of about 0.5% and chronic liver disease does not occur with Hepatitis A. Transmission typically occurs via the fecal-oral route and the incubation period (the development of symptoms) is about 28 days (but even up to nearly 2 months), so by the time a community has an obvious outbreak, many members of the community will already by exposed.
Measles, Mumps, and Rubella (MMR): The characteristics of measles includes, fever, rash, cough, runny nose, “red eyes”, and some unique lesions…Koplik spots…which can be found inside the mouth. A wide range of complications can occur, but the more concerning ones include encephalitis (1 in 1000 cases), subacute sclerosing panencephalitis (SSPE)…typified by a degenerative process in the central nervous system resulting in significant behavioral and cognitive loss and seizures, and death (1 to 3 children in 1000 cases). Mumps is characterized by swelling of the salivary glands, most often the parotid glands…which are found in the head and neck region. A wide range of complications can occur…including hearing deficits, neurological deficits and orchitis (inflammation of the testicles) which can result in sterility. The symptoms of rubella typically are mild and usually involve rash, swollen lymph nodes and a low grade fever but there still exists (albeit very small) some complications including encephalitis. The greatest concern surrounding rubella, however, involves a woman acquiring rubella during pregnancy, which can result in miscarriage, fetal death or congenital rubella syndrome…which can include eye, heart, hearing, and neurological consequences.
Meningococcal disease: The story often associated with this illness involves a college student living in the dorms (or a military recruit living in close quarters with other recruits) who becomes infected with the bacteria (Neisseria meningitides) and causes either a serious bloodstream disease or meningitis or both…often leading to limb loss, neurological deficits, or even death. When the bloodstream is involved, a rash that includes little red spots scattered through out the body or purplish/reddish skin discoloration will occur. And as with any meningitis, presentation is often with fever, vomiting, headache, and neck stiffness but the greatest concern is because things may move so rapidly, death may follow (in up to 10-15% of those who become infected) in just 24-48 hours. Dorms, military bases, summer camp lodging are among the locales where easy spread of this disease may occur among non-immunized individuals. Furthermore, those with spleen issues and certain immune system disorders also need to be protected from this disease.
Human Papillomavirus (HPV): Although many different types of the virus exist, HPV Types 16 & 18 cause about 70% of cervical cancer cases and Types 6 & 11 cause 90% of genital warts cases. This virus is transmitted by genital sexual contact and many infected persons do not realize they are infected or have transmitted the virus to someone else. And although it is very uncommon, genital HPV can also be transmitted to a newborn during delivery…where warts can ultimately develop in the throat of the child. And how common is HPV? Well, these days about 20 million individuals in the U.S. are infected and estimates include 11,000 U.S. women were diagnosed with cervical cancer just last year. A two or three dose vaccine schedule (depending on what age the vaccine is first given) exists to cover the HPV Types mentioned above and others. Think of it as the second cancer preventing vaccine we have (after the Hepatitis B vaccine)…a remarkable thing indeed. As far as any concerning adverse events, after 20 million doses of the vaccine, there is no evidence indicating an increased incidence of GBS above what we would expect to see in the general population.