COVID-19 Vaccine + Infection Provides Strong Protection for Over 6 Months [Reading Science]

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] A study has found that people with 'hybrid immunity'?either infected with COVID-19 before vaccination or infected after vaccination?have strong protection against infection and severe illness for at least six months.

According to the international academic journal Nature on the 8th, a research team from the Oswaldo Cruz Foundation in Rio de Janeiro, Brazil, concluded this after examining medical records of people infected with COVID-19 from February 2020 to November last year. People who received one vaccine dose after COVID-19 infection had a 45% lower chance of reinfection compared to those unvaccinated. Those who completed two doses were 65% protected from infection, and the rate of avoiding severe illness was over 80%.

A Swedish research team reported similar results. Analyzing data from the Swedish Public Health Agency from March 2020 to October 2021, they found that people who recovered from COVID-19 had a 95% reduced risk of reinfection, and receiving one vaccine dose further reduced the risk by about 50%. The second dose allowed this enhanced protection to remain stable for six months.

The UK Health Security Agency also confirmed similar findings after investigating the infection status of thousands of healthcare workers from March 2020 to September 2021. People previously infected with COVID-19 had over 80% protection for one year, which decreased to about 70% after one year. Receiving two vaccine doses resulted in nearly 100% protection for at least six months after the second dose. Victoria Hall, an infectious disease expert at the UK Health Security Agency, stated, "Although immunity from infection or vaccination wanes over time, a high level of hybrid immunity remains."

These research findings provide a basis for encouraging vaccination among those who refuse it, citing antibody formation after COVID-19 infection, such as Brazilian President Bolsonaro. They also serve as a warning against some countries recommending only one vaccine dose for COVID-19 recovered patients.

However, there are limitations as the studies were conducted before the emergence of the recent Omicron variants. Dan Kelly, a professor of infectious disease epidemiology at the University of California, pointed out, "Omicron variants are very different from the viruses studied above, so these findings may not apply to people infected with Omicron after vaccination."