With HIN1 vaccine shortage expected, highest-risk groups go to front of line
Who is at risk for serious infections and why?
By Gary Evans
Senior Managing Editor
Hospital Infection Control & Prevention
With a vaccine shortage projected for novel H1N1 influenza A, only the highest priority groups are likely to be offered the shot when initial lots are cleared for distribution this fall. These groups include critical support personnel such as health care workers, as well as people at risk of severe complications if infected: pregnant women, young children, and those ages 5 to 18 with chronic medical conditions.
Time is of the essence. The estimated mid-October initial vaccine release date is expected to coincide with a resurging wave of the first pandemic flu virus in 41 years. "There is a lot of circulating H1N1 virus in the Southern Hemisphere right now causing a lot of trouble," says Donald Kennedy, MD, a professor of infectious diseases who is running clinical trials on the H1N1 vaccine at St. Louis University. "The anticipation is that this is coming back."
A wider risk pool of H1N1 vaccinees was initially identified, but public health officials are now expected to target the highest-risk groups because there will be considerably fewer doses than the 120 million originally projected.
"It appears we are going to have about half [of what was estimated]," Kennedy says. "The second half is going to take longer to manufacture. It may not be until December or later and that's a problem."
Public health officials estimate that up to 195 million doses may be distributed incrementally by the end of 2009. However, with two doses required per vaccinee, many people will remain at risk if H1N1 spreads as widely as anticipated. In particular, the immunocompromised still could be in jeopardy even if vaccinated. No vaccine is 100% effective in any case, but they may also struggle to mount an immune response. That essentially means that the people at risk for H1N1 complications also warrant immediate consideration for antiviral treatment if symptomatic. Though it was unclear which group would be at the absolute front of the line, the people cited by the Centers for Disease Control and Prevention to receive H1N1 vaccine during a shortage are detailed as follows:
• Health care and emergency services personnel with direct patient contact
Frontline health care workers are a high priority because immunization will protect both them and patients, particularly those with underlying conditions. In a case that set an ominous tone for the resurging pandemic, a healthy 51-year-old oncology nurse who worked in Carmichael, CA, died in July of a coinfection with H1N1 influenza A and methicillin-resistant Staphylococcus aureus (MRSA). With MRSA endemic in many hospitals, this deadly bacterial-viral coinfection may hit other health care workers as the pandemic unfolds. In general, older people seem to have some residual immunity to H1N1, so younger health care workers may be at more risk of infection. There are concerns about maintaining adequate staffing to deal with a pandemic if health care workers are infected, or for that matter, not offered the vaccine. "I don't want to come to work and take care of an H1N1 patient if I am not vaccinated against H1N1," Kennedy says.
• Pregnant women
Historically at risk of flu infection, pregnant women appear to be highly vulnerable to H1N1 infection. "The highest-priority message is to treat pregnant women with influenza-like illness as soon as possible; treatment should not be withheld pending results of testing for influenza, if testing is done," the CDC reports on its H1N1 web site. An excess of influenza-associated deaths among pregnant women was reported during the pandemics of 1918-1919 and 1957-1958. Adverse pregnancy outcomes have likewise been reported following previous influenza pandemics, with increased rates of spontaneous abortion and preterm birth, especially among women with pneumonia, according to the CDC.
The reasons pregnant women are so vulnerable are not completely understood, but prevailing theories include some compromise of the immune system, Kennedy says. "This is an observed phenomenon — when pregnant women get the flu, they get it bad," he says. "They can have a lot more morbidity and mortality compared to age-matched controls that were not pregnant."
• People who live with or care for children younger than 6 months of age
"When a child is born the only immunity he has is what is passed from the mother at the time of birth," Kennedy notes. Of course, if the mother has been immunized during pregnancy, some residual protection against H1N1 may occur in the infant. In general, however, unless their caregivers are immunized, infants with fledgling immune systems could be infected with H1N1. Safety concerns trump risk in terms of actually vaccinating babies, who may not have an immune response to the shot anyway, he adds.
• Children 6 months through 4 years of age
This group is expected to be able to achieve immunity, though the six-month cut point is somewhat arbitrary. "The older they get, the better they respond to protective immunity," Kennedy says. Some think this group and possibly older children may be particularly prioritized because children do not generally practice hygiene etiquette and are robust viral shedders when infected. Thus, immunizing children could have the secondary effect of protecting their adult contacts.
• Children 5 through 18 years of age who have chronic medical conditions
"People with underlying medical conditions — diabetes and renal failure, etc. — their immune systems are not normal," Kennedy says. "When they get flu infections they tend to be more severe. If you're going to target a protective strategy with limited resources you are going to be looking at who is likely to get [HIN1], but also who is going to do poorly if and when they get it."
According to the CDC, underlying conditions that could complicate H1N1 infection in all age groups include cancer, blood disorders (including sickle cell disease), chronic lung disease [including asthma or chronic obstructive pulmonary disease (COPD)], heart disease, kidney disorders, liver disorders, neurological disorders (including nervous system, brain, or spinal cord), neuromuscular disorders (including muscular dystrophy and multiple sclerosis), and people with weakened immune systems (including people with AIDS or those who are receiving chemotherapy).1
CDC recommendations for people with chronic conditions during the pandemic include:
— Seek medical attention if you have a fever and symptoms of the flu.
— Limit contact with crowds and avoid crowded places. If you can't avoid crowded settings, consider wearing a facemask or respirator to decrease your chances of getting infected.
— Be careful not to touch your face, and wash your hands often.
— It is estimated that staying at least 6 feet away from a person who sneezes or coughs may be a safe distance.
— Talk with your doctor about having a two-week supply of medication.
— Keep the name, phone number, and office address of your doctor or health care provider with you at all times. Find out the best way to communicate with your doctor.
— Get a written record of the kind of chronic disease(s) you have and the treatment you are receiving. Keep this information with you at all times.
— Prepare a typed or printed list of all medications usually taken and the times of day they are taken. Also include necessary medical supplies or equipment such as syringes, strips, lancets (if you have diabetes), or oxygen (if you have COPD).
— Determine how you will access ongoing medical care such as chemotherapy or radiation therapy. Ask your health care provider if they have a plan to deal with a severe flu outbreak.
— If you use medications for your condition, continue taking them even if you become sick with the flu, unless your doctor or health care provider says otherwise.
— Be alert to changes in your breathing, especially if you have heart failure, congestive heart disease, or COPD. Promptly report changes to your doctor or health care provider.
Reference
- CDC. Information about the Flu — including the new H1N1 Flu — for People with Certain Medical Conditions. Available at: http://www.cdc.gov/flu/professionals/flugallery/2009-10/pdf/certain_medical.pdf.
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