People who got COVID-19 in the early stages of the pandemic weren’t especially safe from catching the virus again when the omicron variant swept the world, according to a study.

Those who were infected with alpha, beta and delta variants were only 36% better protected from reinfection with omicron about 10 months later than people who hadn’t had the disease, University of Washington researchers said Thursday in the Lancet. However, the group was able to avoid hospitalization with omicron, and death, almost 90% of the time over the same period.

The findings, derived from a meta-analysis of 65 studies from 19 countries, may help health officials steer vaccination campaigns and form policy recommendations. The COVID-19 pandemic was particularly hard to cope with because the behavior of the novel virus was mostly shrouded in mystery, and researchers are still uncovering new information about how it affects people.