Why Grandma can’t get a vaccine appointment: the queueing problem that will keep on happening

A few weeks ago, state and county authorities — to the extent there is anyone who can be called an authority right now — had an operational problem. The slots for precious vaccine doses were not filling up, and vaccine was even expiring, being thrown out, and going to waste.

What happened?

Strict rules of who should receive the vaccine, in what priority order (also to protect against favoritism, corruption, or inequity), were not producing enough willing people to fill all the slots available. Nurses were being underutilized, vaccines were being underutilized. And when you have a time-expiring medicine that everyone wants urgently and is scarce, that matters.

It’s easy to understand why this could happen (despite some more troublesome issues convincing people to take a vaccine that can save their life). Getting people aware and coordinated on short notice to physically show up at a place for a time-sensitive slot is no trivial problem, especially when the systems for doing this are being invented on the fly.

Imagine the pool of available people to be vaccinated in say, the 1st week of the vaccination campaign, and the number of slots that a health service can offer. Some people from category 1a are filling slots, and some, but not as many from 1b (due to lack of information, inability to sign up, a variety of reasons), leaving you with nurses with no one to administer doses to:

Week 1 of the vaccination campaign queue: willing people and slots for them, but underutilization.

So, if you were a public health administrator, what would you do about this problem? You have slots that are going begging for people, yet you know of lots of other people you can potentially call on.

Well, they did the most obvious and easy thing: they asked to open up eligibility to more people (category 1c, for example) and draw on more candidates to fully utilize the slots. And this would not be an incorrect solution in a narrow sense — you’re putting more doses of vaccine in people’s arms, which is an overall goal of the campaign.

Week 2: slots opened up to more categories, but an important problem — every category is now treated the same in a single queue, swamping higher priority category people

But this simple and easy solution produced a very important side problem: if you don’t have a queue that keeps track of people’s relative priority as you open up more tiers, there are certain people in the most important categories who will always miss getting a slot even if they try very hard to.

Why? Suppose you have a website to administer the slots and decide who gets scheduled. If you open up another category as eligible, but then treat every one as having equal priority, the opening up of category 1c will swamp everyone in category 1a and 1b who should have been treated as higher priority.

Think in terms of someone’s likelihood to receive a slot being given out at random. You (in category 1a or 1b) suddenly have to compete with everyone in category 1c. Never mind the issue that healthcare workers may be very busy and unable to sit at a computer all day to find a slot, or that people aged 75+ are more likely to have issues using a new reservations systems and clicking a mouse fast enough to outcompete the 2x number of people in the next category.

So, what happens? Grandma just can’t seem to get an appointment, despite being among the top priority people who we want to get a vaccine to.

Perhaps you’ve experienced this very problem trying to help vulnerable family members. Perhaps you patiently awaited public health authorities to announce that it’s your 75+ year old parents’ turn to get vaccinated, only to see them jump ahead and open it up to everyone above age 65.

Under this kind of operational queueing system, until the number of slots starts to match the population still waiting, the people you most want to reach may keep on missing out on a chance to be vaccinated because they are outnumbered by everyone else.

Week X, and so on: every time a new category is opened up to keep slot utilization high, people in previous (higher priority) categories are outnumbered for available slots.

And this will keep on happening with every next tier that authorities open up if they take this approach whenever they see that appointment slots are starting to become underutilized.

That public health authorities didn’t anticipate this problem or have a solution ready for it is worth a whole podcast on its own, certainly. After all, what is the CDC or a county public health department but a planning and preparation organization? But aside from that, what should be done about this problem?

Well, instead of adopting the simplistic approach above, public health authorities can be just a bit more sophisticated and start operating queues that are priority-aware.

Basically, enable a multiple queue system that allows anyone of a higher category to receive priority on a given day, even when the next tier has been opened up. And combine that with having on-call waiting lists of people who are ready and willing to take any available spot the next day if slots become underutilized.

Not that complicated — a better queuing system that doesn’t leave people behind: draw people for each day’s slots with their priority preserved

Putting a system in place like this will help make sure that the people we really need to be vaccinated get a fighting chance to be scheduled.

These are problems, but legitimate ones to experience when a process is brand new and unfamiliar to everyone concerned. But how you fix something often says more about one’s capabilities than how you got in the situation in the first place.

Just a little bit more sophistication and proper planning in how the vaccine is administered will help serve the goals of this campaign much more effectively. And just as importantly, it can help restore a lot of faith in local and federal governments’ ability to manage this crisis, and people’s sense of having competent government.