How will the pandemic end?

What you can see from the graph is that current daily infections in the US dropped like a rock in February 2021. That’s great news if you compare it to December 2020 and January 2021, when daily cases were hitting 250,000! But daily cases now seem to have plateaued at around 70,000 per day. That’s about the same number of cases during the peak of what we now call the second wave of the virus last summer, when most of the country had imposed new restrictions on businesses and gatherings. So is now the time to let down our guard? Ummmm, give me a second ... think ... think … No! Grrr.

Since there are apparently going to be as many flavors of recommendations, mandates, and restrictions as there are states, cities, and counties, it seems that everyone will be on their own to figure out what they should do in the next few months. Newly vaccinated people are especially likely to be wondering what they can do. Can they visit their grandchildren? Can they go back to group lessons at their Pilates gym? How about private lessons? How about church? Would any of these activities put them in danger themselves? Would they be endangering others, like their grandchildren’s parents or playmates, or like their still unvaccinated friends?

How to decide?

In this article, I unveil (ta-da!) my own personal pandemic visualization tool. Your students can create their own using objects they find at home. I used pasta (my default choice for both science activities and dinner), but Lego blocks, M&M candies, or a variety of breakfast cereals would work too. The point is to create a concrete (don’t use concrete, though; it’s definitely too heavy) representation of what the pandemic looks like right now, and how ongoing vaccination campaigns will change the risk landscape over time. This can be used to think about how risky any particular activity might be, for you or those you come into contact with. You can look at it from the point of view of a vaccinated person, or someone who’s recovered from COVID, or someone who’s still susceptible.

Here’s the key to the different kinds of pasta:

And here are some of the things you should bear in mind as you consider the risk of any given activity:

1. Fully Vaccinated (farfalle, aka butterfly): If you have received both doses of the two-dose vaccine (or one dose of the one-dose vaccine):
   1. If you are exposed to the virus, you are unlikely to develop any symptoms or to become seriously ill. Yay!
   2. However, you may still contract the virus and pass it to others. The likelihood of this is not known, but it’s not zero. Boo!
   3. If a new variant of the virus emerges (more about that later), you are still not likely to show symptoms if exposed to it, but you are probably more likely to contract and potentially spread the virus.
2. Partially Vaccinated (half farfalle/butterfly): If you’ve received only your first dose of the two-dose vaccine, your risk of contracting the virus drops considerably after 10-14 days, and if you contract it, you will likely not get very sick. You can still spread the virus to others if you contract it.
3. Recovered (penne, aka smooth tube): If you’ve recovered from COVID-19, your risk of contracting it again, or at least of showing symptoms, seems to be quite low. How long that immunity lasts is unknown, but we are not seeing a surge of reinfections, so for the moment, immunity appears to last at least 6-9 months.
   1. If a new variant starts to spread in your community, you may be at risk of a new infection, although probably at considerably lower risk than someone who’s never had COVID-19. Another unknown.
   2. If you’ve recovered from COVID-19 and gotten at least one dose of a vaccine, you are thought to be as fully protected as someone who’s received two doses.
4. Susceptible (rotini, aka curlicue): If you’ve never had COVID, you are vulnerable to contracting it. If everyone in your pandemic pod has had the disease or been vaccinated, your risk is probably pretty low, but not zero if any of your podmates are engaging in activities where they are likely to be exposed to the virus (for example, attending large gatherings or having close contact with non-pod members).

So here’s how to use the visualization tool.

Figure 1 is our current situation. About 16 percent of the population has gotten one or two doses of the vaccine. About 20 percent are thought to have already contracted the virus (this is a super rough estimate — there’s lots of disagreement about this). Anyhow it clearly varies a lot from place to place, so you can adjust it for your locality. That leaves about 64 percent of the population still vulnerable.

Let’s say you are fully vaccinated and you want to know whether it’s safe to go to an indoor church service with 100 people. Find a piece of pasta that looks like a butterfly: that’s you! Now look at what’s around you. Are you surrounded by other vaccinated people (butterflies or half butterflies, aka farfalle), or are there some susceptible people (curlicues, aka rotini) nearby? If you are near any rotini, you could inadvertently spread the virus to them. Maybe you should wait on going to church in person. Definitely wear a mask if you go.

Now, let’s take a look at how the situation will have changed a month from now. In this pastascape, I’ve assumed that vaccination continues at a pace of around 1.5 million doses per day for the rest of March. That should bring us to about 30 percent of the population partially or fully vaccinated. I assumed that another one percent or so of the population would be infected and recovered during the month (that’s if the current 70,000 cases per day rate continues).

You can march through the same examples. You’ll see that vaccinated people are in contact with a lot fewer susceptible people. (Students could actually calculate the change by counting the number of curlicues around each butterfly and calculating the average number of contacts with susceptible people — the number should go down each month.)

Finally, here is a projection of what the situation might be like by the end of April 2021, assuming that another one percent of the population contracts and then recovers from the virus and another 20 percent of the population is vaccinated (assuming vaccination rates rise to 2 million people per day, which is the current goal):

You can see that the situation really is very different from early March 2021. The 30 percent or so of the population that is still vulnerable is now scattered among people who are vaccinated or recovered. The odds of a vaccinated person being in contact with someone from whom they might unknowingly contract the virus is much lower (students can figure out how much the average has changed).

The bottom line is: we’re close. We’re really close. The big wild cards that are left are how quickly we can get people vaccinated and how people behave between now and then. The first wild card controls how quickly risks will go down. The second wild card controls how many people will get sick in the meantime.

You may have noticed that I never once mentioned herd immunity. And that’s because I don’t think it’s the most helpful way to look at the situation. People tend to talk about herd immunity as though it will magically appear all of a sudden, heralding a return to normalcy. But the question isn’t When do we reach herd immunity so we can go back to normal? Attaining herd immunity is not so much a goal as a result that will emerge (or not) depending on our actions; the goal that we can actually contribute to reaching is the reduction of risk. So the question is, "What should we do right now?" Our behavior will determine how quickly and effectively we reduce the spread of the virus. Risk will definitely decline over time, but our behavior can drive the risk down faster. The more we can hold cases down (Wear your mask! Maintain social distance! Avoid indoor gatherings!), the less likely it is that susceptible people will become infected and that vaccinated people will contract and spread the virus, drawing out the pandemic.

Do I need to add: Get a vaccine, any of the vaccines, as soon as you can? If so, consider it added!