SHOOTING ADULTS
A group of health advocates expounds on the value of protecting adults from many vaccine-preventable diseases
Through vaccination, potentially fatal and as yet incurable diseases can be prevented.
Because of the persisting notion that vaccination is something that only infants and children should undergo, most adults are unaware of the fact that they continually expose themselves to a wide range of possibly fatal diseases. And since most of those that are susceptible to these diseases are in their most productive years, morbidity and mortality bring with them significant economic costs.
This problem is not unique to the public--even health-care practitioners themselves are not always fully aware of the significance of vaccination. Because of this, the need to administer vaccines is rarely ever broached to patients.
To make doctors--and in effect adult Filipinos--more attuned to the significance of vaccination, the Philippine Society for Microbiology and Infectious Diseases (PSMID), together with the Philippine Foundation for Vaccination (PFV), published Handbook on Adult Immunization for Filipinos last year.
Dr. Remedios Coronel, chair of the PSMID task force on adult immunization, wrote in her preface to the handbook that their "objective is to provide standards of care for the prevention of the common infectious diseases" in the country, with emphasis "on the local epidemiology…and on the vaccines." Dr. Lulu Bravo, PFV executive director, pointed out that vaccine-preventable diseases in adults are "sometimes ignored in less developed countries because priority is usually given to very young infants and children, [among whom] mortality rate from such diseases is highest."
And so for the protection of adults, vaccination is a must.
Back to basics
Immunity is the ability of the body to protect itself from infectious diseases. It does this by recognizing and tolerating the presence of material indigenous to the body (self) and eliminating foreign material (nonself). Immunity is often characterized by the presence of antibodies that are specific to a single antigen.
Immunity may be acquired two ways--actively or passively. Active immunity develops when a person's own immune system produces antibodies, either through an infection or through vaccination. This is usually more permanent. Passive immunity occurs when antibodies are transferred from another person or animal. In nature, this occurs through the transfer of maternal antibodies to the offspring, either transplacentally or through colostrum. Immunoglobulins can also be obtained from previously infected humans and animals to provide protection to the person receiving them. This kind of immunity is transient and disappears once the transferred antibodies become destroyed.
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There are two general types of vaccines: live attenuated vaccines and inactivated vaccines. Live attenuated vaccines are weakened forms of the live organism. For this vaccine to be effective, the organism must replicate within the body to incite an immune response that is similar to the natural infection. This makes the vaccine unstable and susceptible to interference from circulating antibodies in that factors that could kill the attenuated organism, before or after it has been injected into the body, could render the vaccine ineffective. Usually, one dose is enough to incite immunity. However, since the vaccine is an attenuated version of the natural organism, it can incite severe reactions just as the wild forms can.
Inactivated vaccines, on the other hand, are not alive and therefore cannot replicate. The immune response to these vaccines is humoral and therefore minimally affected by the presence of circulating antibodies. However, these vaccines are not as effective as live attenuated vaccines in inducing an immune response: they generally require three to five doses before effective protection is achieved and antibody titers fall over time. Inactivated vaccines can contain the whole organism or just fragments of the organism. In general, the more similar a vaccine is to the natural disease, the better is the immune response to the vaccine.
Although the widespread administration of vaccines following a set of guidelines has been encouraged, there are certain contraindications to the giving of vaccines. For example, live vaccines are not to be given to pregnant women or to immunocompromised patients. The only permanent contra-indications to vaccination are severe allergies to a prior dose of the vaccine/vaccine component or encephalopathy following administration of pertussis vaccine.
Over the years, there have been concerns about the perceived adverse reactions following vaccinations. In fact, some of these concerns are without basis. For instance, the tetanus toxoid was rumored to be abortifacient, causing a significant setback to many countries' safe motherhood programs. Through proper education, and with the help of their doctors, patients will learn to separate the fact from the myth.
Guidelines to keep in mind
In a forum on adult vaccination organized by GlaxoSmithKline, Coronel gave a quick rundown of the most important
things a clinician must remember when administering vaccines to adults.
Tetanus and Diphtheria
All susceptible adults should be targeted, especially pregnant women and health-care workers. Pregnant women should be vaccinated beginning the second trimester of pregnancy and should complete all three doses two weeks before delivery. Health-care workers are immunized at zero and four weeks, and then six or 12 months later. A booster dose is given every 10 years to improve waning immunity.
Varicella
All individuals 13 years and above with no history of varicella infection or immunization should be targeted for varicella vaccination. This is especially true for health-care workers, teachers, and women of childbearing age. The live attenuated vaccine is given subcutaneously as a single dose to those under 13 years old. For individuals who are thirteen or older, two doses are given a month apart.
Measles, Mumps, and Rubella
All susceptible adolescents and adults should be immunized with this live attenuated vaccine. Specifically, nonpregnant women of reproductive age must receive the rubella vaccine. It is administered in two subcutaneous doses four weeks apart.
Pneumococcus
The pneumococcal vaccine is an inactivated vaccine and is given intramuscularly. Healthy adults under 60 and those considered at high risk must be given the vaccine. The vaccine affords immunity after a single dose. However, revaccination after five years is required to maintain protection.
Typhoid
Vaccination against typhoid is recommended to those who are at an increased risk of exposure to the disease or those who are already infected and are at risk of transmitting the disease to others. The vaccine comes as an oral enteric-coated capsule, which is a live attenuated vaccine, or an intramuscular Vi capsular polysaccharide Ty 21. The capsule is given in three doses, given every other day, one hour before a meal, with a cold drink. The intramuscular vaccine is given as a single dose. A booster dose is also recommended every two to three years.
Rabies
These unique set of individuals are given preexposure prophylaxis against rabies: health-care workers in hospitals that treat dog-bite and rabies cases, rabies-research diagnostic workers, veterinarians and veterinary-medicine students, and field workers.
Influenza
Vaccination with with the influenza vaccine is recommended for those at risk of developing complications, like those with chronic diseases, who are 50 years and above, and are pregnant. It should be given between February and June every year.
Hepatitis A
Vaccination is recommended for those living in high-prevalence areas like the Philippines. Various preparations are given as one or two doses, with an additional booster dose.
Hepatitis B
As for hepatitis B, universal immunization should be considered. The vaccine is usually given at zero, one, and six months, but special circumstances may require accelerated administration.
Special Focus
Hepatitis and influenza
Three crucial vaccine-preventable diseases need stronger attention among health-care professionals--hepatitis A and B, and influenza.
Dr. Salvacion Gatchalian, assistant director of the Research Institute for Tropical Medicine, said that many liver diseases "account for millions of infections worldwide." Viral hepatitis (A, B, and C), has a rate of 7.6 per 100,000 in the Philippines.
Hepatitis A is a viral infection that commonly manifests with flu-like symptoms and anorexia. Up to two-thirds of patients with the disease may exhibit icteresia. Although the disease does not have chronic sequelae, its tendency to occur in sporadic and epidemic cyclic patterns carries with it a heavy burden to an affected society. The virus is transmitted via the fecal-oral route. It is therefore prevalent in poor areas with low levels of sanitation.
The vaccine has been recommended for routine use in high-prevalence areas, the Philippines included, where all susceptible individuals may be considered for active immunization. Of special mention are persons traveling or working in countries with high or intermediate rates of disease, children, individuals engaged in high risk behavior, patients with chronic liver disease, food handlers and those that work with primates who are also sources of transmission.
Various vaccine preparations are available and are given as one to two doses with an additional booster dose. But in general the vaccine is highly immunogenic, so much so that after the first dose, 90- to 95-percent seropositivity can be expected. After the second dose, there is 100-percent seropositivity and seroconversion.
Meanwhile, over two billion people worldwide are infected with hepatitis B. The Philippines ranks as one of the hyperendemic areas for hepatitis B where the lifetime risk of developing the infection is more than 60 percent. Unlike hepatitis A, the disease carries with it a gamut of serious, chronic sequelae--fulminant hepatitis, cirrhosis, hepatocellular carcinoma, and death.
In the Philippines, the most frequent route of transmission of hepatitis B is vertical transmission from mother to baby. In the light of this, it is recommended that the first dose of the vaccine be given at birth for all Filipino infants. A universal hepatitis B immunization program is actually the strategy of choice. The World Health Organization recommends mass immunization of all infants, children, and adults to afford significant global reduction of hepatitis B infect-ion. Failing this, routine immunization with the inactive hepatitis B vaccine is recommended for all immigrants from hyperendemic areas, hemodialysis patients, IV drug users, homosexual males, household contacts of all HBV carriers, recipients of blood pro-ducts, and health-care workers with frequent blood contacts.
The ideal hepatitis B vaccination schedule is a three-dose regimen at zero, one, and six months. However, should special circumstances require it, an accelerated schedule can be done to complete the course within a shorter period (zero, seven, and 21 days, with a booster dose at 12 months).
Newer vaccines both for hepatitis A and B have recently been introduced into the market. These new preparations carry with them the benefit of improved convenience, and fewer visits to the physician, which then improve compliance with the vaccination regimen. The dosing schedule for this combined vaccine is zero, one, and six months, at the end of which time there is a nearly 100-percent seroconversion protective against both hepatitis A and B.
Dr. Cecilia Montalban, chair of the Philippine General Hospital Therapeutics Committee, discussed the need to protect patients from influenza, which is often taken for granted, but always carries the threat of an epidemic. She said: "It is one of the oldest diseases known to man, and…can only be one of the deadliest."
Common in the country during the rainy season--particularly June to August--influenza has three clinical pictures: the "traditional," fulminant, and complicated types. Montalban said that doctors should beware of fulminant influenza, because it is the one often seen in pandemics. It spares practically no one, has pulmonary mani-festations, and does not respond to antibiotics. The complicated type, meanwhile, can open itself up to bacterial superinfections (otitis media, bacterial pneumonia, and other respiratory disorders) and can lead to decompensation of chronic diseases.
Vaccination with the inactivated influenza vaccine is recommended to everyone, but is more strongly recommended in certain groups. These include the following: those at risk of developing complications, 50 years or older, with chronic diseases, who are immunosuppressed, living in nursing homes, and who are pregnant (in the second or third trimester). Health workers, household contacts, and caretakers of those who are at high risk must also be vaccinated. The vaccine is given yearly, preferably between February and June.
Said Montalban: "Due to the shift phenomenon, which is a major antigenic change, which has intervals of 25 to 30 years, a new severe pandemic can occur, and it is really due any time this year or the next few years. That's why we have to be prepared for this."
It is hoped that through vaccination, potentially fatal and as yet incurable diseases can be prevented. Said Dr. Remedios Coronel: "We have to increase the [vaccination] coverage level for adults. Vaccination is among the best public-health success stories in our lifetime."
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