As often as we talk about our “system”–and will continue discussing how it fares in the field over the next six months–we thought it might be a good idea to give you an idea of what exactly we are talking about. If you are reading this, you are already likely aware that we are here in Benin implementing a mobile, biometric-based vaccine tracking system: in essence, a database of electronic vaccine cards. The overall system is comprised of single physical data acquisition units that reside everywhere vaccines are administered, e.g. hospitals, clinics, mobile vaccination teams. Each unit can be described both in terms of the hardware and the software.


The cornerstone of one of our tracking units is a small, inexpensive netbook computer. Netbooks offer several advantages for how we use them. They are lightweight which puts less of a burden on vaccinators already often tasked with carrying cold boxes full of vaccines. They are energy-efficient which allows them to run on battery out in the field for days without requiring access to electricity. In addition to the netbook, the other key hardware element is the fingerprint scanner, which attaches via USB.


Our software is rather unique. We custom built it, including the fingerprint processing since the use case (tiny fingers of small children) is unaddressed by commercially-available software. Because of the weak or nonexistent communication infrastructure in the most rural areas, we rely on physical data transfer. This requirement led us to employ a less-common type of database. Expect more detail on some of the technical features in a  future post. For now, we will walk through a couple of the steps and you will be able to see actual screenshots of our software.

The process starts by gathering basic information about the child. In the picture below, the health worker is being asked the gender of the child. We also record the date of birth and can record other ancillary information that might be of interest, like what relative brought the child in to be vaccinated or the literacy of the parents. This screenshot highlights an important design feature: simplicity. Health workers fall all across the spectrum of training and capability, so we were forced to design for the most minimally trained. As such, the choices available to the health worker are been minimized and the software flow is as linear as possible. The health worker does not have to choose between several available paths. There is one path and the user can only move in one dimension (forward or backward along the same path).

Selecting the child's gender


After we collect basic information about the child, it is time to scan his or her fingerprints and search for those in the database. In the two images below, you can see the interface health workers use to acquire those fingerprints. From the first screenshot, the health worker will scan the child’s left thumbprint and then the right thumbprint. Once an image is acquired, the software immediately evaluates the quality of the image. Essentially it asks: “Is this image of a high enough quality that it is able to be matched?” We do not want to waste time trying to match a really bad image. The green check marks in the second screenshot tell the health worker that good images were acquired and the system can now search the database for the child. If the images are not good enough, the health worker is told to re-scan the fingerprint.

Prompting the health worker to scan the child's fingerprints


Confirmation that the fingerprint images are of an acceptable quality


Once we have identified the patient, the health worker has several options. As our systems are adopted into new regions, it is inevitable that we will be seeing children at various stages through the immunization schedule. The “View or Modify Patient History” option will show the health worker the vaccination record and allow it to be manually updated. This is useful if we see a child for the first time but he or she has already received some vaccinations. We can copy information from that child’s vaccine card into the system. This option is also useful if a parent has lost the child’s vaccine card and is curious about which vaccines the child has received, which vaccines the child still needs, and when the parent should return with the child for those needed vaccines.

Options available to health worker after patient is identified


When the health worker goes to administer vaccines, they see the electronic version of the vaccine card with more information shown to them to make their job easier. Each row represents a specific vaccine (the Measles vaccine, for instance, or the Diptheria-Tetanus-Pertussis combined vaccine) and each box to the right of the vaccine represents a required dose according to the national immunization schedule. The vaccines and doses are color-coded so the health worker can quickly determine which vaccines to administer. If a vaccine is highlighted in green, the entire series for that vaccine has been completed; if it is orange, then the child is eligible to receive a dose of that vaccine that day; if it is not highlighted, then the health worker knows that the child needs one or more doses but is not eligible for them that day based on either the child’s age or time since the last dose. The health worker can then direct the parent to return in a specific amount of time.

Doses are colored similarly to the vaccine. If a specific dose is in green, it has been previously administered. If it is orange, the child is eligible to receive that dose on that day. If it is in gray, the child still needs the dose but is not eligible for it that day.

Electronic version of the vaccine card