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 have been built. The United Kingdom, for example, has mandated vaccines for all social care staff.
And in Italy, from October 15, workers will have to present to the employer proof of vaccination, a negative covid test or recovery from a recent infection.
Anyone unable to do so risks being suspended from work without pay. Other countries are taking similar measures.
But do vaccines actually limit the spread of the virus? An extensive study conducted by a team at Oxford University and specifically analyzing the Delta variant showed that both Pfizer and AstraZeneca vaccines do reduce the transmission of the disease.
The study looked at nearly 150,000 contacts that were tracked out of nearly 100,000 initial Covid cases.
The initial positive cases contained a mixture of vaccinated and unvaccinated individuals and the aim was not only to see which groups were most likely to transmit the virus, but also which of the Pfizer or AstraZeneca vaccines were most effective in reducing transmission.
The findings showed that both vaccines reduced transmission, but that the Pfizer vaccine was the most effective in this regard.
As with previous research, this Oxford study found that vaccinated and unvaccinated groups had similar levels of the virus in their bodies, but those who were vaccinated were less likely to pass it on to others, suggesting that they eliminate the virus faster. .
There is a problem
The study found that the protection that vaccines offer against Covid-19 transmission decreases over time.
Three months after receiving the AstraZeneca injection, those who had discovered infections were just as likely to spread the Delta variant as those who were not vaccinated. While protection against transmission has decreased in people who have received the Pfizer vaccine, there is still a benefit compared to people who have not been vaccinated.
This sounds daunting, Al Jazeera notes, but it is important to note that vaccinated people have stronger immune systems and will be able to get rid of the disease faster than unvaccinated people.
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