Coronavirus vaccines are extremely effective at preventing the spread of the Alpha variant of the disease but the impact may be less on the more infectious Delta variant, according to researchers at Dutch public health institute RIVM.
The researchers studied how often people who have been fully vaccinated infected others in their household between February and May, when the Alpha variant was dominant in the Netherlands.
The study showed that people living in the same household as people who were fully vaccinated, but picked up coronavirus, were 71% less likely to be infected than household members of unvaccinated people.
Among people who were infected after partial vaccination (at least two weeks after the first jab with the Pfizer, AstraZeneca or Moderna vaccine), 21% fewer household members became infected.
The research results also show that if someone in the household tested positive, fully vaccinated household members were 75% less likely to become infected than unvaccinated household members.