Science of not getting COVID when exposed
September 16, 2020 6:39 AM   Subscribe

My partner got COVID. I was definitely exposed. My antibody test is negative. Please help me understand why.

When I say I was definitely exposed I mean that I was breathed on and shared body fluids with a COVID positive person within 2 days of symptom presentation. About two days after partner showed symptoms, I had mild fever with fatigue and GI symptoms so I got tested for the active virus. The test was negative but the provider told me to assume I had it since I had been exposed to a known positive, and she suspected I might have presented too soon for the test to catch the viral load.

It has been three weeks since I got the test, partner has made a full recovery, and my recent antibody test was negative. Is it possible that I was exposed but somehow didn't get it? If so, how is that possible? We were in each other's personal space without masks for the entire time before partner noticed symptoms. After that I was regularly entering his quarantine space to provide medical care or assist with ADLs. We both wore masks most of the time, but still. I am puzzled how I didn't get the virus, and trying to sort out the likelihood that the antibody test is giving a false negative vs I genuinely didn't get it somehow. Any science based speculation (with links if you have them) is appreciated.

My current primary theory is that I lack the ubiquitousness of ACE2 receptors necessary for the virus to attach, followed by a weaker theory that my existing medical regimen somehow protected me (featuring Plaquenil, quercetin, NAC which may support prevention of covid through increasing glutathione). I have a connective tissue disease that causes inflammation which may explain why there would be a dearth of ACE2 receptors. I have a related theory that my autoimmune condition provides superior immune protection while it also attacks my own body. Any other ideas? Or science based interpretation of my current theories? Thanks.
posted by crunchy potato to Health & Fitness (7 answers total) 6 users marked this as a favorite
I should have also said you are not my doctor and this is not medical advice.
posted by crunchy potato at 6:40 AM on September 16, 2020

Also not a doctor, but my understanding of the immune system is that you might not develop antibodies if the innate part of your immune system fights off the virus early and quickly enough, keeping you from getting infected. Whether this is able to happen is sort of random and depends on where/how the virus enters your body, and how much of it. Although it’s likely that you would contract the virus when sharing a house with someone who has it, it’s not 100% and I’ve read other stories of people who were definitely exposed but didn’t get it.
posted by mekily at 6:49 AM on September 16, 2020 [3 favorites]

The microCOVID project suggests you have a 50% chance of transmission between partners with typical partner behavior. COVID is not perfectly transmissive and you are not infected by exposure to a single virus particle.
posted by saeculorum at 6:51 AM on September 16, 2020 [23 favorites]

If you were tested for an active infection three weeks ago, and you were infected at the time and got a false negative, you'd only have been recovered for a week or two at this point. You may have been tested for antibodies too early for them to show.

One other possibility is that you did have it, but didn't/won't develop antibodies. This preprint discusses cases similar to yours, where people sharing a household with a confirmed case had mild symptoms but did not show an antibody response. At least some of those people showed signs of T-cell response.

Or you didn't get it. As saeculorum says, it's possible.

Regardless of your antibody status and whether you had an infection, given that credible cases of reinfection have been reported, it would likely be wise to continue with any infection prevention protocols you already were following.
posted by pie ninja at 6:59 AM on September 16, 2020 [14 favorites]

It's really not that unusual to not get COVID even if you have a household member who got it. This meta-analysis estimates around 19% of household members get it if there is a known positive case in the house. You would just need to be lucky / not be predisposed to be infected - and not even especially lucky. Just like other viruses, COVID doesn't transmit perfectly even if you are in close contact with someone who has it. In the past, did you always get a cold if your partner got one?
posted by peacheater at 7:12 AM on September 16, 2020 [10 favorites]

Yeah, I agree with everyone above that this may be as simple as a case of "yay immune system." I've known several people who have had enough intimacy with an infected partner to require presumed-positive precautions, yet ultimately turned out to have not contracted the virus at all.
posted by desuetude at 11:29 PM on September 16, 2020 [1 favorite]

Anecdotal and non-explanatory, but this happened to my sister-in-law. Husband was positive for antibodies, she wasn’t. However, he was asymptomatic.
posted by condour75 at 4:08 AM on September 17, 2020 [1 favorite]

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