Thus, since the circulation of Omicron, 2 doses of vaccine offer only limited protection in efficacy and duration against SARS-CoV-2 infection. However, if some studies have already suggested the interest of the booster, the evidence remains limited as to its effectiveness “over time”. In addition, many health systems now recommend a 4th dose for more vulnerable or older people.
3rd dose, what about?
In order to estimate the effectiveness of 3 doses vs 2 against the risks of severe infection and hospitalization linked to COVID-19, Agermose Gram, researcher at the Statens Serum Institut and his team conducted a cohort study at the scale nationwide including all previously uninfected Danish residents. The analysis took into account their vaccination status as well as age, sex, geographical location, and comorbidities, before comparing infection and hospitalization rates according to the number of vaccinations. This analysis confirms that:
The 3rd dose of vaccine certainly provides greater protection against infection and hospitalization in the event of infection with Omicron;