A study published in Nature investigated whether previous non-COVID-19 vaccines can afford protection against infections with SARS-CoV-2. The study finds that polio, Haemophilus influenzae type-B (HIB), measles-mumps-rubella (MMR), Varicella, pneumococcal conjugate (PCV13), Geriatric Flu, and hepatitis A/hepatitis B (HepA–HepB) vaccines that were given in the past one, two and five years are "associated with decreased SARS-CoV-2 infection rates after adjusting for geographic SARS-CoV-2 incidence and testing rates, demographics, comorbidities, and number of other vaccinations."