With input from Dr Monica Vasudev

1458:  Women are reporting more severe side effects after being administered COVID-19 vaccines

1. Side effects appear to be different for men and women across a range of vaccines, often on account of hormones, genes and vaccine doses.
2. The sex difference in COVID-19 appears to be consistent with past reports of other vaccines.
3. A CDC report on safety data from the initial 13.7 million COVID-19 vaccine doses administered in the U.S. noted 7,000 people who reported side effects. Of these, about 79% were women. Around 61% of the vaccines were administered to women.
4. CDC researchers have found in another report that all 19 people who had anaphylaxis following the Moderna vaccine were female. With the Pfizer vaccine, 44 out of the 47 people who had anaphylaxis were women.
5. CDC studies have also noted that four times as many women developed allergic reactions after the 2009 pandemic flu vaccine.
6. From 1990-2016, women reported 80% of the anaphylactic reactions to vaccines.
7.   Overall, women seem to have more reactions to vaccines for the flu and hepatitis B, and also for the combined measles, mumps and rubella vaccine.
8. Women have a more robust immune system that is capable of producing more antibodies in response to vaccines. This could possibly be associated with reproductive hormones.
9. Estrogen can cause immune cells to produce more antibodies while testosterone can suppress the production of immune chemicals.
10.   Immune-related genes are present on the X chromosome, of which, women have two copies while men have one. This could partly explain why more women have autoimmune diseases.
11. Women have greater immunity - whether its to ourselves, or to a vaccine antigen, or to a virus.
12. Women and men absorb drugs differently, with women often requiring lower doses for the same response.
13. COVID-19 vaccines, which provide the same dosage to everyone, could lead to varied responses and side effects in people. COVID-19 vaccine side effects reported by women appear to be mild and short.

[Sources: New York Times, "Women Report Worse Side Effects After a Covid Vaccine."

CDC, "First Month of COVID-19 Vaccine Safety Monitoring — United States, December 14, 2020–January 13, 2021."

CDC, "Reports of Anaphylaxis After Receipt of mRNA COVID-19 Vaccines in the US—December 14, 2020-January 18, 2021."]

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA