A new study from Israel suggests immunity gained after recovering from a bout of COVID-19 is more protective against the new Delta variant than vaccine-induced immunity. Natural immunity was estimated to be about 13 times stronger than having two doses of the Pfizer-BioNTech vaccine.
The study “Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections” is published on the medRxiv* preprint server.
Israel had one of the fastest vaccine rollouts globally. Currently, over 13 million doses have been administered in the country. As a result, the findings make up the largest real-world observational study comparing natural to vaccine-induced immunity.
Increased breakthrough infections and hospitalizations in vaccinated individuals
Vaccinated individuals with no prior exposure to SARS-CoV-2 had a 13.06-fold increased risk of becoming infected with the Delta variant. In addition, there was a 27-fold elevated risk for symptomatic COVID-19.
Additionally, vaccinated individuals showed a greater risk of requiring hospitalization from a breakthrough infection than unvaccinated individuals with natural immunity.
More research investigating the long-term protection of natural immunity is still needed. However, the researchers theorize that natural immunity could be providing a larger immune response towards SARS-CoV-2 proteins than the anti-spike protein immune activation offered by the Pfizer-BioNTech vaccine.