Antibody Responses 3-5 Months Post-Vaccination with mRNA-1273 or BNT163b2 in Nursing Home Residents

Nursing home residents in Ontario, Canada, were prioritized for vaccination with mRNA vaccines from Moderna (mRNA-1273) or Pfizer (BNT163b2) in December 2020-January 2021, which significantly reduced the high morbidity and mortality due to COVID-19.1 Nursing home residents often fail to mount robust responses to vaccinations2 and recent reports of breakthrough infections, particularly from variants of concern, raise questions about whether vaccination regimens elicit a sufficient humoral immune response or if booster doses are warranted.