Isn't natural immunity better than vaccine immunity?
Here is what the checked sources say. Each title links to the original.
Immune system and vaccines
CHOP's page (reviewed November 2025) says natural infection almost always causes better immunity than vaccines, often after one illness instead of several doses, but that the price paid can be pneumonia, intellectual disability, birth defects, liver cancer or death, depending on the disease. It also says vaccines do better for some diseases: tetanus toxin causes disease in amounts too small to trigger lasting immunity, so survivors still need the vaccine, and the HPV, pneumococcal and (for children under 2) Hib vaccines produce stronger immune responses than natural infection.
Measles virus infection diminishes preexisting antibodies that offer protection from other pathogens
Researchers used a lab test (VirScan) that tracks antibodies to thousands of germ fragments in blood from 77 unvaccinated children before and two months after measles. Measles eliminated 11% to 73% of that measured antibody repertoire, depending on the child, with antibodies recovering after natural re-exposure to those germs. Infants who got the MMR vaccine did not show this effect. The study measured antibodies, not later illnesses. Two authors disclosed advisory roles with vaccine makers (Sanofi, GSK).
Long-term measles-induced immunomodulation increases overall childhood infectious disease mortality
Using population data from high-income countries, researchers found that deaths from other infectious diseases in children tracked measles incidence with a lag of 2 to 3 years, both before and after measles vaccines were introduced. The authors concluded that long-term immune effects of measles drive these swings, and that their data offer an explanation for the broader benefits of measles vaccination. This is a population-level association study, not a trial, and it did not measure any individual child's immune impairment.
Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression
A 2023 review funded by WHO and CEPI pooled 26 observational studies (searched to June 2022) on omicron-era COVID-19. Its modelled estimates: past infection alone gave 74.6% protection (95% CI 63.1 to 83.5) against hospitalization or severe disease at 12 months, but 24.7% against reinfection. Infection plus primary-series vaccination (hybrid immunity) gave 97.4% (91.4 to 99.2) against severe disease and 41.8% against reinfection at 12 months. Protection against reinfection waned within months, and many estimates had serious risk of bias. Several authors reported unrelated grants or fees, including from Pfizer.