Omicron Infection After Vaccination Provides Protection Against Other Variants [Reading Science]

South African Research Team

[Asia Economy Reporter Kim Bong-su] A study has found that individuals who experience breakthrough infections with the Omicron variant after receiving a COVID-19 vaccine develop stronger immunity against other variants such as Delta.

On the 11th, the international academic journal Nature reported that a research team from the University of KwaZulu-Natal in South Africa recently published these findings. The team measured changes in the neutralizing ability against the COVID-19 virus from 6 to 23 days after symptom onset in 39 individuals infected with Omicron. Among them, 15 had received Pfizer or Janssen vaccines but experienced breakthrough infections, while 24 were unvaccinated at the time of infection.

As a result, vaccinated individuals with Omicron breakthrough infections showed a 12.0-fold higher neutralizing ability against the Delta variant compared to unvaccinated individuals. The unvaccinated group had 17.9-fold lower immunity against the original pre-variant COVID-19 virus and 4.8-fold lower neutralizing ability against the Omicron BA.2, also known as stealth Omicron variant.

Immunity against the Omicron variant was also significantly stronger in vaccinated individuals with breakthrough infections. On the 6th day after symptom onset, vaccinated breakthrough cases showed a 13.6-fold increase in Omicron neutralizing ability compared to previous levels, whereas unvaccinated individuals showed a 6.0-fold increase. Measurements taken after 23 days also showed that vaccinated individuals had 2.2 times higher neutralizing ability than unvaccinated individuals.

The research team explained, "These results indicate that hybrid immunity, resulting from vaccination combined with Omicron infection, provides protection against Delta and other variants. Conversely, individuals who recover from Omicron infection without vaccination receive only limited protection."