How often will unvaccinated people get COVID? Study

# Unvaccinated people should expect to catch COVID-19 every 16 months

Story at a glance

The Yale School of Public Health analyzed data on natural immunity to estimate how often unvaccinated individuals can expect to become reinfected with COVID-19 for a new study.
The study determined that natural immunity is somewhat short.
Individuals who are unvaccinated can expect to be reinfected with the coronavirus roughly every 16-17 months.

A new study by the Yale School of Public Health has analyzed data on natural immunity to estimate how often unvaccinated individuals can expect to become reinfected with COVID-19.

“The overall goal of the study was to provide an answer to a question that at this point in the pandemic would be impossible to answer empirically, which is how long after you’ve been infected by SARS-CoV-2 can you expect to possess immunity against the virus before you become vulnerable to reinfection?” Hayley Hassler, a co-author of the study, told Yale Daily News.

The study determined that natural immunity is somewhat short, and in a model where everyone has either been infected with COVID-19 or vaccinated against it, those who are unvaccinated can expect to be reinfected with the coronavirus roughly every 16-17 months.

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“Our results are based on average times of waning immunity across multiple infected individuals,” Hassler said. “Any one of those individuals may experience longer or shorter durations of immunity depending on immune status, cross-immunity, age, and multiple other factors.”

According to the latest data from the Centers for Disease Control and Prevention, only 57.1 percent of the U.S. population is fully vaccinated against the coronavirus.

I wonder how often you can expect to get COVID if you are vaccinated? What if you don’t get Boosters every 2 or 6 months?

16 months seems long if you have to get a booster vaccine every 6 months? Now the question is if you had COVID and got vaccinated or the other way around, do you still need to get the booster in 2-6 months or can you go longer?

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OK, I looked for a more detailed explanation of the study and found this article.

From the article, not sure who had the thought that natural immunity would confer lifetime immunity, but…

The findings contradict the notion that recovering from COVID-19 will guarantee a lifetime of protection from the virus.

The study looked at post-infection data from six coronaviruses that are close relatives to COVID-19, dating as far back as 1984. The time period following infection ranged from 128 days to 28 years under endemic conditions, meaning that the disease is constantly found in a population.

Using that data, researchers were able to estimate the reinfection time for unvaccinated people — roughly 16 months on average. That’s less than half the time it takes to get reinfected by other coronaviruses transmitted by humans, they found.

“Reinfection can reasonably happen in three months or less,” Townsend explained in a university news release. “Therefore, those who have been naturally infected should get vaccinated. Previous infection alone can offer very little long-term protection against subsequent infections.”

I’ll be interested to see how I fare next month. For the last 10 years or so (since moving to IL), I’ve suffered from “bronchitis” type symptoms around the end of harvest; with the worst being Nov 2019 (enough that I went to the doc for the “good stuff” to help me sleep).

Since the pandemic hit, and getting the coronavirus vaccine, I didn’t experience the symptoms (certainly not to the extent I had in 2015 through 2018). It will be interesting to see what it’ll be like between now and thanksgiving.

I mean, one can catch the flu every year… (if you really work at it)

You might get lifetime immunity from the COVID variant you got.
But, just like Common Colds, but more sinister, you are not necessarily immune to any and all variants.

Not until you’ve become a Level 3 Paladin, at any rate.


Probably not. The studies I’ve seen suggest you don’t get lifetime immunity to other corona viruses. But you may not get as sick.

This seems like such a bad study in what it is trying to measure.

I am not sure the conclusion that reinfection happens in less than half the time is even a reasonable conclusion. Why would this virus behave so differently than the other coronaviruses?

When you look at vaccines - each subsequent booster raises the the overall immune response. Measuring reinfection rates for an adult population where you only observe the frequency of a second infection in short period of time can’t possibly give us much real useful information.

For the other coronaviruses - you start off and get them as a kid, which just like this one, is rarely severe. And you get them a second time, and a third time, and probably half a dozen times by the time you are an adult.

The real question should be - how many boosters/infections does an naïve adult need to reduce their long term severity to infection to that of the other coronaviruses such that this can just go along and be endemic.

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Me neither.

I can give you one data point.

Wife got covid in Dec 2020, got the vaccine in Jan & Feb 2021, then the booster at some point between then & Nov 2021, then got covid again in April 2022. I certainly don’t know what variant(s) she got. Probably whatever was the style at the time.