She has changed her mind. But she will not get the vaccine after this because she will have natural immunity (her view).

Is your view different? You don't believe natural immunity?

I could be wrong, but I remember reading that a vaccine is more effective than natural immunity

You are correct. A recent study found that un-vaccinated individuals are 2.34 times as likely to be re-infected than vaccinated individuals.

Get vaccinated.

https://www.cdc.gov/mmwr/volumes/70/wr/mm7032e1.htm