What are the most serious side effects of the 9-valent vaccine?

Generally speaking, the "9-valent" refers to the 9-valent recombinant human papillomavirus (HPV) vaccine. There is no such thing as the most terrible side effect of the 9-valent recombinant HPV vaccine. Possible side effects of the 9-valent recombinant HPV vaccine include severe allergic reactions, fainting, joint pain and swelling, thrombocytopenic purpura, and menstrual disorders. Detailed explanations are as follows:

1. Severe Allergic Reactions

The 9-valent recombinant HPV vaccine contains excipients such as yeast protein and adjuvants. In some individuals, the immune system may recognize these components as foreign antigens, triggering an immune response. The immune system produces large amounts of antibodies and releases inflammatory mediators like histamine, causing symptoms such as rash, itching, rapid breathing, and decreased blood pressure. In severe cases, this can even lead to anaphylactic shock.

2. Fainting

During vaccination, some individuals may experience enhanced vagal nerve reflexes due to psychological stress, pain stimulation, and other factors, leading to vasodilation, decreased blood pressure, reduced cerebral blood supply, and subsequent fainting. In addition, receiving vaccination on an empty stomach or while experiencing excessive fatigue or other suboptimal physical conditions can also increase the risk of fainting.

3. Joint Pain and Swelling

The immune response triggered by the vaccine may cause abnormal autoimmune reactions, wherein the immune system attacks joint tissues, leading to synovial inflammation in the joints and resulting in symptoms such as joint pain, swelling, and restricted movement. These symptoms typically occur in large joints, such as the knees and elbows, and may last for several weeks or even months.

4. Thrombocytopenic Purpura

After receiving the 9-valent recombinant HPV vaccine, antibodies may mistakenly attack platelets, causing a decrease in platelet count and disrupting the body's clotting mechanism. This can lead to symptoms such as skin petechiae, purpura, nosebleeds, and gum bleeding. In severe cases, it may cause internal bleeding.

5. Menstrual Disorders

Components of the vaccine may have a certain impact on the female endocrine system, interfering with the normal secretion and regulation of hormones, leading to menstrual cycle irregularities and abnormal menstrual flow, such as decreased or increased menstrual bleeding.

By receiving the 9-valent recombinant HPV vaccine and maintaining good lifestyle habits, individuals can effectively reduce the risk of HPV infection and protect their health.