Your Local Epidemiologist: Reinfections

Long story, short:

  • Reinfections more common with new omicron variants (up to 30% of new cases).
  • Reinfections are much more rare within 90 days of prior infection, but rise as immunity wanes.
  • Reinfections tend to be much more mild, especially for younger, healthy people and/or those with updated vaccines.

The most important reason for posting this is that she discusses this confusing paper on health risks associated with reinfections. Scroll down toward the end of her article to read. There’s a very helpful graph illustrating her point

The viral pre-print sent shockwaves through media, as the study was widely misinterpreted to say the health risks from reinfections are worse than risks from primary infections. This is not what the study showed.

The authors did not compare reinfections to the same person’s primary infection. Instead they compared people with reinfections to a separate cohort of people with primary infections (see figure below). Because of this, the only thing we can conclude is that being infected again is worse than not being infected again, which is expected.

I find her emails so helpful for sorting all of this out.

I think the key takeaways of that excellent blog post are these:

What about long COVID after reinfection?

We desperately need more research on long COVID, and we need to sufficiently recognize it as a risk of infection. I couldn’t find much on the risk of long COVID due to re infections. We can hypothesize lower risk given lower viral load, but this is an educated guess and we don’t know how long COVID occurs or how to treat it.

Bottom line

There are myriad reasons we need to do our best to reduce SARS-CoV-2 transmission and prevent infection. Wearing masks, staying up to date with vaccines, and improved ventilation will help. And, ideally, reinfections would not occur. But we are well past the point of zero COVID, and reinfections can be expected, just like with other respiratory viruses. Vaccine and infection-induced immunity is clearly reducing severity of reinfection. Unfortunately, protection from severe reinfection isn’t guaranteed for high-risk groups.

Even though we are more than two years into this pandemic the amount of definitive information that we know about “Long Covid” would fit into a shot glass with enough room left over for a double pour of Black Bush. There are still no definitive criteria for suffering from the syndrome nor any kind of diagnostic test that can be used to confirm it, and therapies have varied widely but for the most part sufferers seem to recover or not dependent primarily on their individual responses, with no definitive evidence of efficacy of any particular therapy or treatment. (And yes, people are dying of ‘Long Covid’ if not in the quantity of those from acute primary infection.)

Given that this pathogen is likely to remain in the human population indefinitely and that most people are at some point going to fall into a high risk group, this is an area that really bears more focus. Ultimately, a broadly effective Sarbecovirus vaccine is really needed to forestall this illness; the attempts to produce variant-specific vaccines are inevitably going to be fighting the last war by the time they are deployed.