这里有一点去年感染新冠病毒后今年五六月份再次感染的证据。数据很小，可能不具代表性。

The research determined that unvaccinated Kentucky residents who had a confirmed coronavirus infection last year had a "significantly higher likelihood of reinfection" than those considered fully vaccinated. The study concluded that the unvaccinated were 2.34 times more likely to contract COVID-19 again.

The study involved 246 Kentucky residents who were reinfected in May and June this year after having a confirmed 2020 case. They were compared to 492 controls who had a 2020 infection but were not reinfected.

https://www.google.com/amp/s/thehill.com/policy/healthcare/566799-overnight-health-care-study-finds-unvaccinated-more-than-twice-as-likely-to%3famp