No difference in post-COVID vaccination side effects for BRCA1/2 carriers in Singapore

Individuals with germline genetic alterations, particularly the BRCA1/2 pathogenic/likely pathogenic variant (PV/LPV), do not appear to experience any significant increase in post-COVID vaccination side effects, as reported in a study from Singapore.

“Our observations on the side effects profile were consistent with the general Singapore population and other cancer patient cohorts, defined by predominantly mild and self-limiting effects such as myalgia, fever, and headache, with no severe side effects,” according to the investigators from the National Cancer Centre Singapore.

In the study, 189 participants (median age 50 years), of whom 97 carried PV/LPV in BRCA1 and 92 in BRCA2, completed a phone call survey of COVID-19 vaccination uptake and toxicity. The vaccination uptake rate was 89.5 percent mostly for Pfizer-BioNTech/Comirnaty or Moderna/Spikevax mRNA vaccines. Most of the participants received the two-dose vaccine schedule, and only 4.1 percent received just one dose. [Hered Cancer Clin Pract 2023;21:5]

Myalgia was the most common postvaccination side effect, with a frequency of 56.5 percent. Other side effects were fever in 40.2 percent of participants, headache in 16.3 percent, and fatigue in 11.2 percent. None of them reported experiencing major severe side events, such as anaphylaxis or hospitalizations.

Logistic regression analysis showed that the frequency of side effects was not influenced by PV/LPV gene (BRCA1 or BRCA2), gender, race, age, or history of cancer. In the cohort overall, 95 percent of cancer patients were women as opposed to only 64 percent of noncancer patients. This is consistent with literature, where men with BRCA1/2 PV/LPV are often silent carriers, according to the investigators. [BMC Cancer 2018;18:179]

In line with CDC data

“The nature of side effects postvaccination from our survey were similar to the vaccine studies reported on the Centre for Disease Control and Prevention (CDC) website,” the investigators noted. “Although participants were not [queried on the] grade of the side effects, the reporting of events in a categorical manner allowed us to compare the observations reported by CDC.” [https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/reactogenicity.html]

“In the age group between 18 and 55 years of age, the percentage of individuals reported to have local reactions such as redness and swelling was between 4.5 percent and 6.3 percent, comparable with our participants with rashes at 6.5 percent,” they added.

Reports of “fever and chills” in the CDC groups were between 3.7 percent and 35.1 percent as compared with 40.2 percent in the study cohort. Headache appeared to occur with greater frequency in the CDC groups (41.9 percent) than in the study cohort (16.3 percent). On the other hand, fewer participants in the study cohort (11.2 percent) than in the CDC groups (47.4 percent to 59.4 percent) experienced fatigue.

No reason to avoid vaccination

“Although Singapore is one of the highest vaccinated countries in the world, vaccine hesitancy remains in a subpopulation, including individuals with cancer predisposition syndromes,” the investigators stated.

In light of the findings, “recommendations with regard to COVID-19 vaccination for eligible individuals with germline PV/LPV in BRCA1/2 should not differ from noncarriers and should be encouraged by their healthcare providers,” they added.

The study was limited by the small sample size and lack of a control cohort without germline PV/LPV in BRCA1/2.