# How (and why) to get tested for CMV

As you may know, [I’m not a fan of cytomegalovirus (CMV)](https://denovo.substack.com/p/cytomegalovirus-the-worst-herpesvirus), a herpesvirus that is usually asymptomatic, but causes all sorts of bad things like immune aging and birth defects.

Over the last few months I’ve been following Moderna’s efforts at making a CMV vaccine. [It seems like they’re having some success at inducing antibodies against CMV](https://www.niaid.nih.gov/news-events/novel-cmv-vaccine-generates-stronger-response-key-immune) and hopefully these will provide protection from infection. The [full Phase 3 trial](https://clinicaltrials.gov/study/NCT05575492) is probably going to be completed sometime in the next few years. Initially it will likely be prescribed only to women of reproductive age,[^59s3s9mrme] but I’m hoping that I could eventually receive it myself. But if I already had CMV, there wouldn’t be much point in trying to avoid infection until I could get the vaccine.

So, I wanted to get tested for CMV. But how could I get tested, given that the test requires a prescription and I didn’t have one? The first thing I thought of was to see if the blood bank at Boston Children’s Hospital, where I regularly donate, would be able to test my blood. However, it turns out that they don’t perform CMV testing on their donations. I was a bit surprised by this, but apparently if they [remove all the white blood cells](https://pubmed.ncbi.nlm.nih.gov/10919221/) from the blood sample they can nearly eliminate the risk of transmitting CMV even if the donor is positive.

I also thought of making my own PCR-based test, and I even designed PCR primers for this, but I realized the sensitivity wouldn’t be high enough, as CMV+ people tend to have a low viral load if the virus is latent and not actively replicating.

After a bit of searching, I found a website called [Request a Test](http://www.requestatest.com) where you can directly get a test order with a diagnostic lab. After paying $65, I got an appointment at a local Quest Diagnostics site. At the site, a phlebotomist took a blood sample from my arm, and Quest tested it for anti-CMV antibodies.[^6gdvw5oru3]

The day after my appointment, I got an email from Request a Test, which I nervously opened.

[![](https://substackcdn.com/image/fetch/w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F44cf68d9-3c62-46a6-8207-d3ffa8d6ee0b_1794x726.png)](https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F44cf68d9-3c62-46a6-8207-d3ffa8d6ee0b_1794x726.png)

To my relief, it turns out I don’t have CMV. I was expecting to be CMV positive, given the amount of things I stuck in my mouth as a 3-year old in daycare.

So, why might you want to get tested for CMV? There are two main reasons: first, if you want to avoid infecting other people, and second, if you want to know whether you could benefit from a future vaccine. And at $65 for a test (and probably an hour of time traveling to the site and getting tested), it isn’t too much trouble to get tested.

[^59s3s9mrme]: If a pregnant woman is infected, CMV can cause birth defects in the fetus. 

[^6gdvw5oru3]: If you have antibodies against CMV, unless you’re a vaccine trial participant it means you are CMV positive.