How Hybrid Immunity Could Protect You From Serious Cases Of COVID-19

The Centers for Disease Control and Prevention (CDC) recommends getting a COVID vaccine even if you've already been infected with the virus because if you don't, your risk of getting re-infected increases. Although a COVID vaccine doesn't completely protect you from getting infected, it can reduce your risk of severe illness, hospitalization, or death. Now researchers are finding that a previous COVID infection and a vaccine might give you a double punch in protecting you from severe illness from COVID-19. It's called "hybrid immunity."

According to a 2021 article in Science, a COVID infection and a vaccine offer two paths to immunity. Like two plants that are bred to build a stronger plant, the immune response is much larger when these two paths to immunity are combined. Immunity from both a COVID infection and a vaccine can produce up to 100 times more antibody responses. New research comparing post-infection immunity with hybrid immunity has found support for this claim.

A 2023 study in The Lancet Infectious Diseases reviewed studies about post-infection and post-vaccine immunity published between January 2020 and June 2022. For people who had COVID-19 without vaccination, their immunity was 74.6% effective in protecting against severe illness or hospitalization for up to 12 months. After 12 months, their level of protection dropped to 24.7%.

People with hybrid immunity had 97.4% immune effectiveness against severe illness for 12 months after their primary series vaccination. After 12 months, their immune effectiveness dropped to 41.8%. Those with hybrid immunity who received a booster shot also had 95.3% immune effectiveness for six months. Six months after their booster, their protection dropped to 46.5%.

Although the Centers for Disease Control and Prevention says you can wait three months after a COVID infection to get a vaccine, this study suggests that you'll still have improved immunity up to six months if you've already had at least the primary series of the vaccination. However, the CDC still recommends staying current on vaccinations if you or your loved ones are already at increased risk of severe illness from COVID.