A new study shows that two months after the second Pfizer/Moderna vaccination, antibody response decreases 20% in adults with prior cases of COVID-19. The study also tests how well current vaccines resist emerging variants. The Northwestern University study underscores the importance of receiving a second dose of vaccine, not only because it is commonly known that immunity from vaccines wanes over time, but also because of the risk posed by emerging variants, including the highly contagious delta variant.
