By Sola Ogundipe
Meanwhile, a laboratory study from Japan suggests that COVID-19 vaccination followed by a breakthrough COVID-19 2 infection months later offers greater protection against the Omicron variant than does vaccination with infection soon after.
Vaccinated people who have had an infection are thought to gain strong immunity, at least for a time.
The finding implies that countries that saw large numbers of non-Omicron infections in late 2021 have an advantage as 2022 rolls in with the new variant.
The study has not yet been peer reviewed.
The researchers at Japan’s National Institute of Infectious Diseases in Tokyo, wanted to understand whether the country’s mostly single-source immunity would leave the population especially susceptible to Omicron.
The team collected antibodies from people in Japan who had received two doses of the Pfizer–BioNTech COVID-19 vaccine and later been infected with either the Alpha or Delta variant.
They tested these antibodies’ ability to protect cultured cells from SARS-CoV-2 infection, and found that the length of time between a person’s vaccination and the breakthrough infection was strongly correlated with how well the individual’s antibodies protected cells against infection — particularly with Omicron.
Immunologist Jenna Guthmiller at the University of Chicago in Illinois cautions that the results are solely correlative.
But, she adds, “they are in line with immunologists’ general understanding of how antibody responses mature over time.”