It has long been established that Covid-19 vaccines reduce the risk of serious illness and hospitalization. But until recently, there was a question mark about reducing the transmission of the virus.
It is also an important question around which public health policies are built. The UK, for example, has made vaccinations mandatory for all social care staff.
And in Italy, from October 15, workers will have to provide the employer with proof of vaccination, a negative covid test, or evidence of recovery from a recent infection.
Anyone who fails to do so risks being fired for free. Other countries are taking similar measures.
But do vaccines really limit the spread of the virus? A comprehensive study conducted by a team at Oxford University that specifically analyzed the Delta variant showed that both Pfizer and AstraZeneca vaccines reduced transmission of the disease.
The study looked at around 150,000 people followed from around 100,000 initial Covid cases.
The first positive cases involved a mix of vaccinated and unvaccinated individuals, and the goal was not only to see which groups were more likely to transmit the virus, but also to see which of the Pfizer or AstraZeneca vaccines was most effective at reducing transmission.
The findings showed that both vaccines reduced transmission, but the Pfizer vaccine was the most effective in this regard.
As with previous research, this Oxford study suggested that vaccinated and unvaccinated groups had similar levels of the virus in their bodies, but those who were vaccinated were less likely to transmit the virus to others, which in turn eliminated the virus more quickly.
There is a problem
The study found that the protection offered by vaccines against Covid-19 transmission diminished over time.
Three months after receiving the AstraZeneca injection, those who discovered the infections were just as likely to spread the Delta variant as those who had not been vaccinated. While protection against transmission decreased in people who had the Pfizer vaccine, there was still a benefit compared to people who had not been vaccinated.
Al Jazeera notes that this sounds scary, but it’s important to note that vaccinated people have stronger immune systems and can recover from the disease faster than unvaccinated people.