VARIABILITY IN CLINICAL PRACTICE
Variations from clinical best practices can be influenced by many different factors, including experience, education, and
"real-life" clinician scenarios (e.g., multi-tasking, distractions, or work-flow pressure). While the vaccine enterprise in
the US is considered safe, there have been case studies that show that errors in preparation and administration can occur.
In 2010, Premier Safety Institute conducted a large study with more than 5000 clinicians to understand the "current injection
practice patterns to assist with targeting outreach and education." This study was done in response to "increasing reports
of outbreaks in the US involving transmission of Hepatitis B and C to patients associated with unsafe injection practices
and breakdowns in basic infection control" (8). For example, an outbreak occurred during the 2007–2008 influenza campaign
when a New York physician's office engaged in a practice of drawing six 0.5-mL influenza vaccine doses into a 3-mL syringe
and subsequently vaccinated six individuals with the same syringe while only changing the needle (9).
The Premier study revealed that this practice may be more widespread than perhaps anticipated: 0.9% of the clinicians in the
survey reported that they change the needle but reuse the syringe on multiple patients. In this same study, 6% of the clinicians
also reported using single-dose or single-use vials for more than one patient, and 1.1% reused a syringe to enter a multi-dose
vial and then saved that vial for use on another patient (8).
CDC guidelines recommend that healthcare workers use single-dose vials, syringes, and needles only once, which precludes their
use in more than one patient. The study authors wrote, "Our findings provide evidence that healthcare professionals continue
to engage in unsafe injection practices, which represent an ongoing threat to patient safety in the United States and are
devastating to all those patients who are impacted." (8)
THE IMPACT OF VACCINE PACKAGING AT THE USER INTERFACE
In a recent article in the American Journal of Infection Control the authors stated, "Although there is a clear need for more education, this may not necessarily eliminate all unsafe practices.
Adopting principle from human factors engineering, we must consider redesigning devices, equipment, and processes to reduce
or eliminate risk of bloodborne pathogen transmission" (8). This statement is consistent with FDA's increasing requirements
around the integration of Human Factors Engineering (HFE) and device design. HFE is "the science and the methods used to make
devices easier and safer to use....helping to improve human performance and reduce the risks associated with use" (10).
To better understand the user interface of clinician and various vaccine packages, and the associated potential for errors,
a comprehensive study was commissioned by BD and conducted in 2011 by Interface Analysis Associates (11). The researchers
outlined the process of vaccine preparation from storage through disposal for the three vaccine package types, and then developed
a list of all potential errors associated with each step. The study identified all distinct operations within each risk category
for potential contribution to risk.
Table I: The top five potential risk categories and the number of associated potential operations associated with each risk.
The top five potential risk categories and number of associated potential operations that could cause them are shown in Table
I. The study concluded that, in general, the more complex the particular workflow and the more risk factors involved, the
more apparent were the benefits of PFSs compared with vials. For example, of the 43 distinct operations determined for Contamination,
both MDVs and SDVs were subject to 38 of these risk opportunities while PFSs were subject to only 23 of them. Similar differences
were seen across the rest of the top five risk categories.
One can also relate the findings of the study to Six Sigma principles. Six Sigma principles are used to help mistake-proof
products and/or processes and rely on the following general approaches:
- Eliminating the possibility of error
- Replacing a risky process with one that is more reliable
- Facilitating or making the task easier to perform
- Detecting errors before carrying out further operations
- Mitigating or minimizing the effects of error.
In the user interface study, the number of distinct steps involved in delivering vaccine from the three packaging platforms—up
to 50 for multi-dose vials, 45 for single-dose vials, and 28 for PFSs—suggests an advantage to the simpler PFS protocol. By
reducing the number of steps, there is less opportunity for error.
For example, PFSs have a demonstrated advantage in contamination control because needle changes and drawing drugs from vials
(and all the contamination potential those steps entail) do not occur with prefills. Similarly, replacing a highly variable
step like syringe filling by a clinician with highly precise aseptic machine filling can help assure administration of the
correct dose, as well as reduce the likelihood of contamination. Finally, opportunities for administering the wrong dose or
expired vaccine are minimized by labels being applied on every PFS by the manufacturer. Preapplied labels thereby facilitate
the task so it is easier, and provide a means of detection as the PFS reaches the end user and point of use with a label.
Readily apparent labels also enable corrective protocols to be followed immediately in the event an incorrect drug or incorrect
dosage is injected, thus mitigating further effects of the error.
Being prelabeled, unit-dose, and ready-to-administer, PFSs embody "safety-by-design" because of their inherent simplicity
to use, elimination of several error-prone steps in vaccine preparation and administration, reduced opportunity for syringe
reuse and cross-contamination, and assurance of the correct dose. Printed peel-off labels on vaccine prefills can facilitate
recording of batch numbers and updating immunization records.