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.

The study also showed that prior exposure to SARS-CoV-2 does not guarantee a high level of antibodies, nor does it guarantee a robust antibody response to the first vaccine dose. This directly contradicts the assumption that contracting COVID will naturally make someone immune to re-infection. The findings further support vaccination (and two doses), even for people who have contracted the virus previously.

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