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Pneumonia

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of pneumonia.

Prevention

The best way to prevent serious respiratory infections such as pneumonia is to avoid those who are sick (if possible), and to practice good hygiene. [For detailed information see the In-Depth Report #94 Colds and influenza. ]

Good Hygiene and Preventing Transmission

Colds and flus are spread primarily when an infected person coughs or sneezes near someone else. A very common method for transmitting a cold is by shaking hands. Everyone should always wash his or her hands before eating and after going outside. Ordinary soap is sufficient. Waterless hand cleaners that contain an alcohol-based gel are also effective for every day use and may even kill cold viruses. (They are less effective, however, if extreme hygiene is required. In such cases, alcohol-based rinses are needed.)

Antibacterial soaps add little protection, particularly against viruses. In fact, one study suggests that common liquid dish washing soaps are up to 100 times more effective than antibacterial soaps in killing respiratory syncytial virus (RSV), which is known to cause pneumonia. Wiping surfaces with a solution that contains one part bleach to 10 parts water is very effective in killing viruses.

Dietary Factors

Foods Containing Lactobacilli (Good Bacteria). Friendly bacteria inside the intestines may also help keep you healthy. Researchers are studying the possible protective value of certain strains of lactobacilli bacteria found in the intestines. One such strain is acidophilus, which is used to make yogurt. According to one Finnish study, children attending day care who drank milk containing the strain lactobacilli GG reduced their risk of respiratory infections by 10 - 20%. More research is needed. (The strain used in the Finnish study was not the kind found in most commercial yogurt products.)

Vitamins. Studies are mixed when it comes to whether or not vitamin supplements protect against upper respiratory infections. Large doses of vitamin C, for example, may help reduce the duration of a cold, but they do not appear to protect against one in the first place. Two studies in 2002 on multivitamins reported opposite results, with one finding fewer infections and one finding no difference. It is possible that vitamin C or multivitamin supplements may be helpful in specific people, such those who are vitamin deficient or have medical problems that impair their immune systems.

Studies on vitamin E specifically have been largely negative. A 2002 study reported a higher incidence and greater severity of respiratory infections in older adults who took 200 mg of vitamin E daily.

Factors That Lower The Risk for Respiratory Infections

Breastfeeding. Some evidence suggests that women who breastfeed reduce the risk of respiratory infections in their children.

Low Stress and Active Social Life. Several studies have reported that socially active people with low stress have fewer colds than people who have high stress levels or those who have low stress and few social connections.

Zinc

Zinc appears to have certain important effects on the immune system ,and it may have a direct effect on viruses. Zinc preparations in lozenge or nasal gel form are now available as cold treatments. However, research findings regarding zinc's benefits have varied. (The differing results may be due to different zinc preparations.)

• A nasal gel (Zicam), which contains zinc gluconate, has shown some success, possibly because the gel sticks to the nasal passages long enough for the zinc to interact with the virus. In a 2003 study, patients who took the nasal gel within 14 to 48 hours of getting sick had less severe symptoms and felt better faster than those who took a placebo. The finding supports earlier studies reporting that Zicam shortened the duration of a cold by about two days.
• Zinc lozenges are showing mixed results. One 2000 study suggested that the use of zinc acetate lozenges (e.g., Fast-Dry, Galzin) may be more effective and have a better taste than other formulations, such as zinc gluconate (Cold-Eeze, Orazinc). On the other hand, a 2002 study reported that zinc gluconate reduced cold duration significantly. To further confuse matters, the two zinc lozenge preparations were directly compared in a 2000 study, and neither was effective. The reasons for these conflicting results are not clear.
• A small 2001 study on a nasal spray preparation found no benefits. The spray preparation had less zinc than the nasal gel.

In any case, no one with an adequate diet and a healthy immune system should take zinc for prolonged periods for preventing colds.

Side Effects of Zinc. Side effects include:

• Dry mouth.
• Constipation.
• Nausea.
• Bad taste (possibly only with zinc gluconate lozenges).
• Overdose may cause severe vomiting, dehydration, and restlessness. Call a physician if any of these symptoms occur.
• In rare cases, an allergic response may occur.

Food and Drug Interactions. Zinc may also interact with drugs or other elements.

• It may reduce absorption of certain antibiotics.
• Foods high in calcium or phosphorus may reduce zinc absorption.
• In high doses and for long periods of time zinc can cause copper deficiencies.

Herbs and Supplements Herbal remedies and dietary supplements are not regulated by the FDA. This means that manufacturers and distributors do not need FDA approval to sell their products. In addition, any substance that affects the body's chemistry can, like any drug, produce side effects that may be harmful. There have been a number of reported cases of serious and even deadly side effects from herbal products. The following are special concerns for people taking natural remedies for colds: Echinacea. The herbal remedy echinacea is commonly taken to prevent onset and ease symptoms of cold or flu. Studies have been mixed on its effectiveness. It is difficult to test, however, since it is available in different species (notably, E . purpurea and E. augustifolia ) and preparations vary from using extracts to dried forms of just the root, the herb, or the whole plant. If echinacea is helpful at all, it may be more effective taken before symptoms develop than during the cold or flu. However, evidence suggests that it is not helpful at all. In addition, allergic reactions have been reported. People with autoimmune diseases or who have plant allergies should particularly avoid it. There have also been some reports of a reaction called erythema nodosum associated with echinacea. This involves a rash, sometimes accompanied by fever, headache, muscle and joint aches, and sore throat. Grapeseed extract is sometimes touted as a natural antihistamine. A 2002 study, however, reported no benefits from it. Chinese herbal cold and allergy medications may contain trace amounts of aristolochic acid, a chemical that is toxic to the kidneys and a carcinogen. Products containing aristolochic acid have been associated with several reports of kidney failure in Europe. Of specific concern are studies suggesting that up to 30% of herbal patent remedies imported from China having been laced with potent pharmaceuticals such as phenacetin and steroids. Most reported problems occur in herbal remedies imported from Asia, with one study reporting a significant percentage of such remedies containing toxic metals.

Anti-Viral Drugs: Neuraminidase Inhibitors

Brands and Benefits. Zanamivir (Relenza) and oseltamivir (Tamiflu) are called neuraminidase inhibitors. They are newer agents that have been designed to block a key viral enzyme called neuraminidase, which helps viruses spread (replicate).

Both zanamivir and oseltamivir have the following benefits:

• Neuraminidase inhibitors are effective for treating both A and B strains of influenza. M2 inhibitors, which prevent the virus from reproducing, are only effective against type A.
• They shorten the duration of the flu by one to three days.
• They may help reduce transmission of the virus, although evidence is needed to confirm these findings.
• They may have a lower risk than M2 inhibitors for emerging viral strains that are resistant to their effects. In fact, on January 14 2006, the Centers for Disease Control and Prevention (CDC) released a Heath Alert (the highest level of importance) regarding the use of M2 inhibitors (amantadine and rimantadine) for the prevention or treatment of flu. Due to significant increase in Influenza A resistance to this class of antiviral medication, the CDC recommended against its use for the remainder of the 2005-2006 flu season.
• They may reduce complications of influenza, although this needs to be confirmed. It is not yet known if they have any effect on overall survival rates.
• They have fewer serious side effects than the M2 inhibitors.
• Both have some benefits for preventing influenza. Only oseltamivir has been approved for this purpose, however, and only in people over 13.

Limitations and Side Effects. Although they have many advantages compared to the M2 inhibitors, they are much more expensive. They also need to be taken within two days of symptoms to be effective. There are also some differences between the two agents that could be significant for some individuals:

• Zanamivir (Relenza) is administered as a nasal spray or inhaler. People with asthma or other lung disorders may experience airway spasms and should use this drug with caution. Side effects are generally minor in most patients. Of concern, however, was a 2001 British study, which found that a majority of elderly patients were not able to properly use the zanamivir (Relenza) inhaler device, making the medicine virtually ineffective in these cases. The study was small, however, and other reports suggest that zanamivir is sill effective in this older group.
• Oseltamivir comes in capsule and liquid form. Side effects are also minor, but about 10 - 15% of patients experience nausea and vomiting. Patients with kidney dysfunction should take lower doses.

Antiviral Drugs for Prevention of The Flu To date both M2 inhibitors and oseltamivir have been approved for prevention of influenza. M2 inhibitors. Amantadine and rimantadine protect against the influenza A infection itself in about half of individuals. Rimantadine is preferred for prevention during outbreaks of influenza A because it has fewer adverse side effects. Neuraminidase Inhibitors. Both zanamivir (Relenza) and oseltamivir (Tamiflu) help prevent both influenza A and B. Only oseltamivir has been approved for this purpose, however, and only in people over 13. Both appear to be very effective in preventing influenza in people who have been exposed to family members with the flu. Antiviral drugs are not a substitute for vaccines. But, they are extremely important add-on therapy for people in certain high-risk groups. They may also be used: In combination with the flu vaccine during seasons where there is a poor match between the virus and vaccine. In high-risk individuals who are vaccinated after the flu season has started. In such cases, it takes about two weeks (or longer in children) for the vaccine to take effect. The anti-viral drugs offer protection during that period. As supplementary protection for vaccinated people in high-risk groups, such as the elderly or people with compromised immune systems. In people who cannot have vaccinations for whatever reason. For people who provide care for high-risk individuals. For high-risk individuals who cannot or will not be vaccinated.

Viral Influenza Vaccines (Flu Shot)

Description of Vaccines. Vaccines against the flu (or a "flu shot") use inactivated (not live) viruses. They are designed to provoke the immune system to attack antigens contained on the surface of the virus. Antigens are foreign molecules that the immune system specifically recognizes and targets for attack.

Unfortunately, the antigens in these influenza viruses undergo genetic alterations (called antigenic drift ) over time, so they are likely to become resistant to a vaccine that worked in the previous year. Vaccines are then redesigned annually to match the current strain.

• Influenza A. The influenza A virus is further categorized by primary molecular antigens (hemagglutinin and neuraminidase), which serve as the targets for the vaccines. Influenza A is a particular problem because it can infect other species, such as pigs or chickens, and undergo major genetic changes.
• Influenza B viruses tend to be more stable than influenza A viruses, but they too vary. Although influenza B has been far less common than A, a vaccine for type B is important because experts are concerned that small children will not have developed any immunity to the virus and will experience severe flu if they are exposed to type B.

A live but weakened intranasal vaccine (FluMist) for healthy people aged 5 to 49 years is approved by the FDA. It is known as a live, attenuated, trivalent, intranasal influenza vaccine (LAIV). The vaccine is engineered to grow only in the cooler temperatures of the nasal passages, not in the warmer lungs and lower airways. It boosts the specific immune factors in the mucous membranes of the nose that fight off the actual viral infections. FluMist is a nasal spray. In one study it protected up to 93% of children against the flu.

Timing and Effectiveness of the Vaccine. Ideally, people should get a flu shot every October or November. However, it may take longer for a full supply of the vaccine to reach certain locations. In such cases, the high-risk groups should be served first.

Antibodies to the influenza virus usually develop within two weeks of vaccination. Immunity peaks within four to six weeks, then gradually wears off. That is why most people should get a flu shot every year.

In healthy adults, the flu shot reduces the chance of illness by about 70 - 90%. The current flu vaccines may be slightly less effective in the elderly and those with certain chronic diseases. But, even in people with weak immune systems, the vaccine is usually protective against serious flu complications, particularly pneumonia. In fact, among the elderly, interesting studies are now suggesting that influenza vaccination may help protect against stroke, adverse heart events, and death from all causes.

Children Who Should Be Vaccinated. The American Academy of Pediatrics (AAP) and the CDC recommend flu shots for all healthy children between 6 and 23 months of age. (The flu shot is not approved for children less than 6 months of age.)

In addition, any child over the age of 2 years who has a condition that requires regular medical care or who has been hospitalized for a serious illness (particularly lung or kidney disease, diabetes, sickle cell anemia, or immune deficiencies) should also receive a flu shot. Children who are receiving long-term aspirin therapy should also be immunized against the flu because they are at higher risk for Reye's syndrome, a life-threatening disease, if they get the flu.

Children with Asthma. Recent and major studies have found that the flu shot is safe for children with asthma. It is very important for these patients to reduce their risk for respiratory diseases. Still, 90% of asthma patients remain unvaccinated.

Older Children and Adults Who Should Be Vaccinated. The following, in order of priority, are the population groups who should be vaccinated each year. The first two groups have the highest need for influenza vaccinations and are given top priority:

• All adults 65 years and older. Older adults who receive a flu shot have lower hospitalization rates than those who don't. Evidence now suggests that vaccination may help protect against adverse heart events (including after heart surgeries), stroke, and death from all causes in the elderly. Still, studies suggest that only two thirds of this group are vaccinated, mostly because of unwarranted fears of ineffectiveness or adverse effects.
• People of any age at high risk for serious complications from influenza. Such people include those with heart disease, lung problems, immune deficiencies, diabetes, kidney disease, or chronic blood disease. (There have been concerns about the safety of the vaccinations in certain high-risk patients such as those with HIV or asthma. Studies now suggest that the vaccine is generally safe in these patient groups. Furthermore, their risk for serious complications from influenza outweighs any potential adverse effects from the vaccines.)
• Adults between the ages of 50 and 64 who have chronic medical conditions. The US Advisory Committee on Immunization Practices (ACIP) suggests that all adults over age 50 should be vaccinated, although this is not recommendation of the CDC.

Other adults who should consider influenza vaccinations include:

• People at risk for flu complications who are traveling to the tropics at any time or to the Southern Hemisphere between April and September.
• Pregnant women who are at risk for flu complications who will be in their second or third trimester during flu season. (Vaccinations should usually be given after the first trimester.)
• Health care providers with direct patient contact, child care providers, and residents of long-term care facilities should also be vaccinated.

Side Effects. Possible side effects include:

• Allergic Reaction. Newer vaccines contain very little egg protein, but an allergic reaction still may occur in people with strong allergies to eggs.
• Soreness at the Injection Site. Up to two thirds of people who receive the influenza vaccine develop redness or soreness at the injection site for one or two days afterward.
• Flu-like Symptoms. Some people actually experience flu-like symptoms, called oculo-respiratory syndrome, which include cough, wheezing, tightness in the chest, and sore throat. Such symptoms tend to occur between 2 and 24 hours after the vaccination and generally last up to two days. These symptoms are not the flu itself, but an immune response to the virus proteins in the vaccine. (Anyone with a fever at the time the vaccination is scheduled, however, should wait to be immunized until the ailment has subsided.)
• Guillain-Barre Syndrome. Isolated cases of Guillain-Barre syndrome occurred in about one of every 100,000 people vaccinated with the swine-flu vaccine in 1976, but it has not been a problem with subsequent vaccines. Guillain-Barre disease can cause paralysis.

Pneumococcal Vaccines

The pneumococcal vaccine protects against S. pneumoniae bacteria, the most common cause of respiratory infections. There are two effective vaccines available: One called a 23-valent polysaccharide vaccine (Pneumovax, Pnu-Immune) for adults, and another called 7-valent conjugate vaccine (Prevnar or PCV7) for infants and young children. Experts are now recommending that more people, including healthy elderly people, be given the pneumococcal vaccine, particularly in light of the increase in antibiotic-resistant bacteria.

Pneumococcal Vaccine in Young Children. The pneumococcal vaccine (Prevnar or PCV7) is very effective in children. Evidence suggests that this vaccination, plus the vaccination against Haemophilus influenzae (an important cause of meningitis), has led to 25,000 fewer cases of serious bacterial infections each year.

The pneumococcal vaccine is now recommended by many experts for the following groups:

• All children up to age two. The pneumococcal vaccine (Prevnar or PCV7) has now been added to the Recommended Childhood Immunization Schedule. The pneumococcal vaccine (Prevnar or PCV7) is very effective in children. Studies are suggesting that it prevents common ear infections as well as serious infections, such as pneumonia. In one study, a similar vaccine under investigation protected not only children in day care from serious respiratory infections, but their younger unvaccinated siblings had fewer infections as well.
• Children up to age five who are at risk for pneumonia or complications of influenza, such as children with sickle disease, those with immune deficiencies, or children with chronic medical conditions.
• Other children age two to five who are higher risk for serious pneumococcal infections should be considered for vaccinations. They include African or Native Americans, children in group child care, socially or economically disadvantaged children, or those who have had frequent or complicated acute middle ear infections within the past year. (In one study, the vaccine reduced the number of ear infections episodes by 6%.)

The recommended schedule of immunization for Prevnar (PCV7) is four doses, given at 2, 4, 6, and 12 to 15 months of age. Infants starting immunization between 7 and 11 months should have three doses. Children starting their vaccinations between 12 and 23 months only need two doses. And those who are over two years old need only one dose.

Pneumococcal Vaccine in Older Children and Adults. The vaccine is proving to be help reduce the rate of pneumonia in young adults, although not to the degree that it protects young children. Its benefits for the elderly, other than protection against bloodstream infection, are unclear. Still, pneumonia is declining among adults, which may be due to fewer infections transmitted from vaccinated young children. Many experts now recommend the vaccine for the following older children or adults:

• All people over 65 years old. (Anyone vaccinated more than five years previously should be revaccinated.) The vaccination is protective against pneumococcal bacteremia (blood infection) in this group, but it does not appear to protect against community-acquired pneumonia itself.
• Adults with any chronic condition that increases the risk for pneumonia. This includes patients with heart disease, chronic lung disease (COPD or emphysema, but not asthma), or diabetes.
• Individuals with immune deficiencies, such as HIV, or those undergoing treatments to suppress the immune system.
• Patients with autoimmune diseases, such as rheumatoid arthritis and lupus. Unfortunately, studies suggest the vaccine may not be as effective in these patients as it is in those with healthy immune systems. Nevertheless they are at high risk for serious respiratory infections and should be vaccinated.
• Patients with kidney disease or kidney transplants. Older people who have had transplant operations or those with kidney disease may require a revaccination after six years.
• Patients with problems in the spleen.
• Alcoholics (especially those with cirrhosis).
• People living in long-term care facilities.
• Alaska Natives or American Indians who may be at increased risk for pneumonia.

Because the vaccine is inactive, it is safe for pregnant women and people with immune deficiencies. In fact, when the vaccine is administered to pregnant women, it may actually protect their infants against certain respiratory infections.

Protection lasts for over six years in most people, although it may wear off faster in elderly people than in younger adults. Anyone at risk for serious pneumonia should be revaccinated six years after the first dose, including those who were vaccinated before age 65. Subsequent booster doses, however, are not recommended.

Side Effects. Pain and redness at the injection site, fever, and joint aches are possible with the pneumococcal vaccine. Children are more likely to have fever side effects within 48 hours if they receive other vaccines at the same time. They are also likely to have fewer side effects after the second dose. In rare cases, such local reactions can be severe. Even if a person is mistakenly re-vaccinated before the effects of the first vaccination have worn off, the risk for severe side effects is very low. Allergic reactions are very rare.

• Review Date: 3/28/2006
• Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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