Why it matters

Many other studies have looked at a small number of alternative covid-19 vaccine rollouts. Our project incorporated more characteristics of the current pandemic and considered 17.5 million possible strategies. We believe this gives our results more authority.

Our model includes differences in disease severity and susceptibility to the coronavirus due to age. It also incorporates social distancing levels that change over time, as well as variable infectivity rates to account for more contagious virus strains such as the delta variant.

All this gave us the ability to accurately assess the CDC’s past decisions. But the greater value of our modeling approach lies in how it could help guide future policy.

By changing model inputs, we were able to show how optimal rollout strategies should change given different vaccine hesitancy rates and for different vaccines that can protect in different ways against infection or death. For countries that are currently planning covid-19 vaccination strategies, our model could help decision-makers develop the most effective strategies given their local resources and specifics. And even in the US, our modeling technique can inform allocation strategies for booster shots and future vaccine rollouts so healthcare administrators can make the best use of limited resources.

What still isn’t known

Any model is a simplification of reality. Our model did not account for re-infections or varying levels of vaccine hesitancy based on socioeconomic status, political ideology, or race. We also assumed that the level of hesitancy was constant over time.

Additionally, some important factors for how the coronavirus spreads—like contact rates between individuals of different age and demographic groups and the contagiousness of asymptomatic and vaccinated individuals—are still unknown. Better data on these parameters would improve the accuracy of our results.

What’s next

Now that we have the model built, we can extend it. For example, we can study how waning immunity and booster shots might affect the spread of the disease. Our computer code is available to the public, and we hope it will guide healthcare policymakers in the US and around the world.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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