Immunocompromised people, including cancer and HIV patients, as well as those who’ve had organ transplants, may also mount a weaker immune response to vaccines.īut many questions remain about boosters. US regulators recommend boosters for elderly people because their immunity from vaccines tends to wane more quickly than average.

Pfizer vaccine less effective after 6 months, study says Similarly, joint pain was more common after the second shot, going from about 9% to 26%. In the first few months after the Pfizer and Moderna vaccines were authorized, 70% to 75% of people reported this side effect after getting either dose.Īdditionally, 50% of people reported systemic side effects after their first dose, which jumped to about 70% after the second dose.Ĭhills and fever, which were reported by only about 9% of people after their first dose, went up to about 30% after the second dose. Most people may experience at least one side effect after getting their dose the most common being an injection site reaction. Females mount a stronger antibody response than males but its a double-edged sword because this is why women have more auto immune disease than men, says Shresta of the La Jolla Institute for Immunology.ĭon’t Miss: Constant Fatigue And Body Aches How Many People Experience Pfizer And Moderna Side Effects

Women also seem to have a more robust immune system, both in their innate responses and in their adaptive immune reactions. Several other factors may also contribute to this gender imbalance.

Joint pain after pfizer first dose