People who have “hybrid immunity,” or have been fully vaccinated and previously infected with COVID-19, have the best protection against the virus, according to two new research published on Friday.
Following two years of a pandemic that infected over 500 million people and vaccinated billions, the research emphasized the necessity of getting vaccinated for those who had natural immunity after recovering from the disease.
One of the two research published in the medical journal The Lancet Infectious Diseases examined the health data of more than 200,000 people in hard-hit Brazil in 2020 and 2021, which has the world’s second-highest COVID death toll.
It discovered that for patients who had already had COVID, Pfizer and AstraZeneca’s vaccinations were 90 percent effective against hospitalization and mortality, China’s CoronaVac was 81 percent effective, and Johnson & Johnson’s one-shot jab was 58 percent effective.
“All four of these vaccines have proven to provide significant extra protection for those with a previous COVID-19 infection,”Julio Croda of the Federal University of Mato Grosso do Sul.
“All four of these vaccines have been demonstrated to provide significant additional protection for people who have previously been infected with COVID-19,” stated study author Julio Croda of the Federal University of Mato Grosso do Sul.
“Hybrid immunity resulting from spontaneous infection and vaccination is expected to be the norm globally and may provide long-term protection even against developing variations,” stated Pramod Kumar Garg of India’s Translational Health Science and Technology Institute in a comment piece connected to the study.
Meanwhile, a study using Sweden’s statewide registry up to October 2021 discovered that patients who recovered from COVID had a good level of protection against re-infection for up to 20 months.
People who had two-vaccine-dose hybrid immunity had a 66 percent lower chance of re-infection than those who only had natural immunity.
The 20 months of “quite good protection” from natural immunity was “much greater than we would predict for the original two-dose vaccine schedule,” according to Paul Hunter, a professor of medicine at the University of East Anglia who was not involved in the study.
However, he noted that both investigations were done before the Omicron variant became common throughout the world, and that it had “significantly reduced the protective benefit of a past infection.”
A study conducted in Qatar and released this week on the medRxiv pre-publication website provided insight into the protection provided by hybrid immunity against Omicron.
Three vaccine doses were found to be 52 percent effective against symptomatic infection of the BA.2 Omicron subvariant—but that percentage increased to 77 percent when the patient had already been infected.
The unpublished study discovered that “hybrid immunity resulting from prior infection and recent booster vaccination confers the highest protection” against both the BA.1 and BA.2 subvariants.