COVID-19 vaccine
COVID-19 vaccine iStock

With Israeli authorities holding off on recommending a fifth vaccine dose against COVID based on their observations of its limited efficacy against the Omicron variant, a new study has confirmed their findings, showing that within half a year of vaccination, protection against symptomatic Omicron-variant coronavirus drops to zero.

The study was conducted in Qatar and published in the New England Journal of Medicine, based on data from the end of 2021 until the end of February 2022. The researchers also found that natural immunity derived from infection with coronavirus was still robust a year after infection, with half the number of previously-infected people contracting symptomatic COVID as compared to those with no previous infection.

Furthermore, after six months passed beyond vaccination, protection against symptomatic COVID was sometimes even negative, meaning that people were more likely to contract COVID than if they had never been vaccinated.

Giving a third (or booster) dose bumped protection up again, but the study only followed booster recipients for 45 days.

However, recent data from the United Kingdom following booster recipients for 20 weeks (five months) shows that protection against COVID by this point is negligible.