Today’s blog post is by History of Vaccines advisor Thomas Fekete, MD, FCPP. Dr. Fekete is infectious diseases section chief at Temple University School of Medicine. This piece follows my post from Tuesday, which looks at mandatory influenza vaccination policies and implementation at Childrens Hospital of Philadelphia and other area health systems.
In the community, influenza can be transmitted at home, at school, at work or in other public venues. During the influenza pandemic of 1918-1919, large public events in cities like Philadelphia were followed by enormous waves of influenza illness and death.
Over the years, recommendations for seasonal influenza vaccine for the public have evolved, but there has always been a push for higher levels of vaccination for health workers. The logic for this is clear: health workers may have a higher risk of exposure at the workplace, and they may have a higher risk of passing on the illness to vulnerable populations. Furthermore, during an epidemic, influenza could incapacitate health workers, and this could compromise many aspects of patient care and public health.
As a scientist, the most appealing way to answer a policy question is to look at research data. Expert recommendations are common but seldom rewarding. However, there is so much literature (going back decades) on influenza vaccination that it can be hard to sort out the relevant studies to address specific questions. In any given year, potential benefits of influenza vaccination are strongly influenced by the degree of match between the circulating strains of influenza virus and those in the vaccine. Although public policy has long encouraged universal influenza vaccination of the elderly, old and chronically ill patients are known to have weaker responses to this vaccine. Since direct immunization is not very protective, the best way to avoid influenza in high-risk patients is to surround them with people who do not transmit infection.
Patients in nursing homes are not exposed to large groups of outsiders, so aside from family and visitors, the people most likely to infect these patients are the staff. Several studies have analyzed influenza rates in nursing home residents in which staff members are immunized versus those where immunization is not required, and the results in terms of patient outcomes do not strongly support worker immunization. Some of the shortfalls of these studies include incomplete worker immunization, inclusion of years in which the vaccine was not likely to be protective, or incomplete recording of eventual influenza. A meta-analysis of these studies (basically an aggregate of the best studies on the subject), showed little evidence of benefit to nursing home residents from health worker immunization. There is very little data regarding benefits to patients from health worker immunization in acute-care or general hospitals.
What a quandary! The current flu vaccines are inexpensive and safe. The live virus vaccine for children and younger adults does not even require a needle and is as good as or better than the vaccine given by injection. But even in a good year, the vaccines do not afford perfect protection. As a health worker, I have come to the selfish conclusion that reducing my risk of getting influenza in exchange for a small injection in my upper arm just makes sense for me. And if others are out sick with flu, I hope that I can be spared from illness so that I can still be here to minister to the needs of my patients. I know that if I am spared influenza, I cannot infect my patients, and perhaps they will avoid getting influenza entirely. Or, they may avoid getting influenza until their overall health is more stable.
In the fullness of time, I expect to see better influenza vaccines with greater activity against more strains. This vaccine could have a much longer period of protection and thus lead to lower total influenza morbidity. A universal vaccine would be a game changer as it could available worldwide. Eventually, it would come off patent protection and be less expensive, an especially crucial benefit in developing countries. A more widely protective flu vaccine could really change the equation of the benefits of health worker vaccination, especially if newer vaccines still fail at a higher rate in the frail and elderly.