The COVID-19 vaccine after radiation therapy

Larkspur

With a little persistence and a tremendous amount of luck, I got my first injection of the Moderna vaccine last Sunday. Among the items on the questionnaire to complete before having the shot was "have you ever had radiation therapy?"

I discussed that briefly with the doctor when I got there. She asked me how long ago I'd had treatment (nearly six years) and said that it could make the vaccine less effective. I hadn't heard that before!--nor could I find any further information about it online.

I didn't press for more details from the doc, as many people were waiting for their turns, and in any case, she was a pediatrician and probably not well equipped to answer in-depth cancer-related questions. I do plan to ask my oncologist, but before I do that, I thought I'd come to our community here to see if anyone can tell us more.

AliceBastable

I'm trying to figure out how radiaction on my left breast could affect a shot in my right arm, and I'm coming up blank. I'm curious if anyone will find and post any reputable, relevant information.

exbrnxgrl

I had rads to a bone met almost 10 years ago. I asked my oncologist if the vaccine was safe for me (I am a teacher and really want it!) and she said absolutely. She is well aware of my bc history and tx and did not mention a word about my prior rads. Additionally, I have not heard of this in general

KMom57

I'm not a doctor, and this is just a guess based on research I've done into another issue. Lymphocytes are very radiation sensitive, as i understand it, and so, often, radiation therapy causes lymphopenia, low levels of lymphocytes. The covid vaccine like all vaccines works by producing lymphocytes which “remember" the virus. If it encounters the virus again, the lymphocytes go into action to fight the infection and protect the body. If I'm correct about that, It would seem logical to me that if one is recently out of radiation therapy, the already abnormally low level of lymphocytes, perhaps combined with a continued delayed destruction of cells (perhaps including the new vaccine lymphocytes) would impact the bodies ability to remember and fight the infection. Again, not a doctor. Just a guess. Edited to add: another guess might be that the radiation somehow suppresses the production of lymphocytes which makes the vaccine less effective for a period of time after radiation? Just a guess. The question I’m interested in would be how long after radiation.

jhl

I am a bit on the front lines and we currently encourage cancer patients receive the COVID vaccine even if under treatment. That coincides with recommendations of MD Anderson & Memorial Sloan Kettering. There are some caveats though. If undergoing whole body radiation with chemotherapy, such as used to completely clear the bone marrow, a vaccine should be delayed until the immune system recovers. If undergoing a short course of radiation for local treatment, you might want to wait 2 weeks after the last radiation. The issue is having a robust immune system to fully allow antibody production. However, as Dr Cohn from The Ohio State Comprehensive Cancer Center indicated, some level of immunity is better than having the disease. For the current two vaccines available, a second dose is recommended to boost the antibody level.

The COVID vaccine is a mRNA vaccine. It is not a live virus vaccine. No live virus vaccines are recommended in anyone undergoing any form of immune suppression.

Larkspur

Thanks, JHL. I'm sure this information will be very helpful to people currently undergoing treatment.

I was wondering about the caveat I received from a doctor, who said that radiation therapy that took place in the past might make the covid-19 vaccine less effective. Do you have any information about that, by any chance?

jhl

Hi Larkspur,

Radiation in the near past (2-10 weeks ago) might give you some residual difficulty mounting a robust immune response. Radiation in the distant past does not confer any long term problems with mounting an immune response.

I will be gentle by saying she was a pediatrician who treats children & young adults who are not sick or who have issues such as asthma, arthritis, etc. Now, if she was a pediatric oncologist, they often do whole body radiation & chemotherapy as I indicated. But, I think you can do your own search to see what major adult cancer centers recommend with regard to the COVID vaccine.

Ladyc2020

KMom. Gosh this sounds a little discouraging. I have my first vaccine scheduled for this Tuesday and I am having some mild lymphadema from rads Nov/Dec 2020. I’ve never even heard of lymphocytes. Now googling....

Ladyc2020

ugh. I first read the study on tamoxifen use and covid ( may be harder to fight) so that helped me decide to get the vaccine... now offered the vaccine as I’m a health care volunteer, and now this about radiation and not being able to mount a robust immune response is very concerning. My appointment is Tuesday morning. I can message my RO tomorrow and see what he says, but perhaps he doesn’t even know. Reading things online and I’m confused.... should I go ahead?! Ughh

Larkspur

Thank you, JHL! This info. is very reassuring, and I'll share it with a couple of friends who went through rads for esophageal and kidney cancer some years back.

Ladyc2020

ok so I was texting my RO today and he strongly advised me to get the vaccine as soon as it’s available to me. He said my body will have replaced the lymphocytes by now... it’s been about 8 weeks since finishing Radiation. Feeling better about it now ☺️

KMom57

Ladyc, sorry, Ididn’t mean to discourage you. Like I said I’m no doctor. Was just guessing why the original poster’s doc might have said it was less effective after rads. Glad to hear that’s not the case!

SpecialK

If you have concerns about lymphocyte status you can have a CBC (complete blood count) done with the white blood cell differential, which will show your current level of lymphocytes. My MO’ office does them with an almost instant read - usually only takes 15 mins or less since they need this info at the ready for patients receiving chemo. If you are worried about it just ask your center if you can have one ahead of your vaccination.

RatherBeSailing

I think the issue is whether the vaccine will be as effective. About a year after radiation I started getting a lot of sinus infections and was diagnosed by an immunologist with low T cell count and low IGG antibodies. She said it was a result of chemo and radiation (large area - chest wall and all nodal fields.) Radiation does kill lymphocytes (T cells and B cells) and the thymus, which produces T cells, shrinks with age. So two years after radiation mine were still low.

This didn't show up in a CBC blood count, by the way, but in testing the various subsets of lymphocytes. And the immunologist also ordered a pneumonia vaccine to challenge my immune system. The good news is that vaccine showed my immune system could still mount a response.

Clearly best to discuss with your primary care doctor or oncologist, who have the knowledge we don't. Personally, I wouldn't ask my RO, who always insists there are no side effects from radiation.

Ladyc2020

thank you everyone! My RO is a young survivor himself X2 and was completely honest about the radiation side effects, especially cancer in the future. I did get the first dose and my arm hurt for about 48 hours... 36 of those it was incredibly painful. Also fell asleep and napped for 2 hours which I never do. Immune response yay!

July152020

I finished my rads on 3/10 and just signed up to get vaccinated. Now I’m worried after reading this...

my RO is on vacation until end of month , let’s hope i get my turn after he’s back.

Ladyc2020

you will probably get chance to speak with a doctor if you get a shot through the public health. I got my shots in my right arm, no nodes removed there.

Don’t worry too much, any side effects from the vaccine are short lived.